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  • Articles  (107,321)
  • Springer  (105,778)
  • Society of Exploration Geophysicists
  • 1985-1989  (92,563)
  • 1950-1954  (14,758)
  • Biology  (87,826)
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  • Articles  (107,321)
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  • 1
    Electronic Resource
    Electronic Resource
    Memory but no suppression in low-dimensional symmetric idiotypic networks (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 223-246 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We present a new symmetric model of the idiotypic immune network. The model specifies clones of B-lymphocytes and incorporates: (1) influx and decay of cells; (2) symmetric stimulatory and inhibitory idiotypic interactions; (3) an explicit affinity parameter (matrix); (4) external (i.e. non-idiotypic) antigens. Suppression is the dominant interaction, i.e. strong idiotypic interactions are always suppressive. This precludes reciprocal stimulation of large clones and thus infinite proliferation. Idiotypic interactions first evoke proliferation, this enlarges the clones, and may in turn evoke suppression. We investigate the effect of idiotypic interactions on normal proliferative immune responses to antigens (e.g. viruses). A 2-D, i.e. two clone, network has a maximum of three stable equilibria: the virgin state and two asymmetric immune states. The immune states only exist if the affinity of the idiotypic interaction is high enough. Stimulation with antigen leads to a switch from the virgin state to the corresponding immune state. The network therefore remembers antigens, i.e. it accounts for immunity/memory by switching beteen multiple stable states. 3-D systems have, depending on the affinities, 9 qualitatively different states. Most of these also account for memory by state switching. Our idiotypic network however fails to account for the control of proliferation, e.g. suppression of excessive proliferation. In symmetric networks, the proliferating clones suppress their anti-idiotypic suppressors long before the latter can suppress the former. The absence of proliferation control violates the general assumption that idiotypic interactions play an important role in immune regulation. We therefore test the robustness of these results by abandoning our assumption that proliferation occurs before suppression. We thus define an “escape from suppression” model, i.e. in the “virgin” state idiotypic interactions are now suppressive. This system erratically accounts for memory and never for suppression. We conclude that our “absence of suppression from idiotypic interactions” does not hinge upon our “proliferation before suppression” assumption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458444
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  • 2
    Electronic Resource
    Electronic Resource
    Book reviews (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 287-291 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458448
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  • 3
    Electronic Resource
    Electronic Resource
    Editorial: Software survey section (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. I 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458449
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  • 4
    Electronic Resource
    Electronic Resource
    Upper and lower bounds from the maximum principle. Intracellular diffusion with Michaelis-Menten kinetics (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 325-335 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Analytical bounding functions for diffusion problems with Michaelis-Menten kinetics were recently presented by Anderson and Arthurs, 1985 (Bull. math. Biol. 47, 145–153). Their methods, successful to some extent for a small range of parameters, has the disadvantage of providing a weak upper bound. The optimal approach for the use of one-line bounding kinetics is presented. The use of two-line bounding kinetics is also shown, in order to give, sufficient accuracy in those cases where the one-line approach does not provide satisfactory results. The bounding functions provide excellent upper and lower bounds on the true solution for the entire range of kinetic and transport parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02460111
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  • 5
    Electronic Resource
    Electronic Resource
    The threshold of survival for systems in a fluctuating environment (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 311-323 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Thresholds for survival and extinction are important for assessing the risk of mortality in systems exposed to exogeneous stress. For generic, rudimentary population models and the classical resource-consumer models of Leslie and Gallopin, we demonstrate the existence of a survival threshold for situations where demographic parameters are fluctuating, generally, in a nonperiodic manner. The fluctuations are assumed, to be generated by exogenous, anthropogenic stresses such as toxic chemical exposures. In general, the survival threshold is determined by a relationship between mean stress measure in organisms to the ratio of the population intrinsic growth rate and stress response rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02460110
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  • 6
    Electronic Resource
    Electronic Resource
    Plant strategies and the dynamics and structure of plant communities (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 409-411 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02460116
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  • 7
    Electronic Resource
    Electronic Resource
    Editorial: Viewpoint (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 415-415 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02460080
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  • 8
    Electronic Resource
    Electronic Resource
    Stochastic models for subpopulation emergence in heterogeneous tumors (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 731-747 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A stochastic analog to a deterministic model describing subpopulation emergence in heterogeneous tumors is developed. The resulting system is described by the Fokker-Planck or forward Kolmogorov equation. A finite element approach for the numerical solution to this equation is described. Four biological and clinical scenarios are simulated (emergence of heterogeneity, exclusion of a subpopulation, and induction of drug resistance in both pure and heterogeneous tumors). The results of the simulations show that the stochastic model describes the same basic dynamics as its deterministic counterpart via a convective component, but that for each simulation a distribution of tumor sizes and mixes can also be derived from a diffusive component in the model. These distributions yield estimates for subpopulation extinction probabilities. The biological and clinical relevance of these results are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02459658
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  • 9
    Electronic Resource
    Electronic Resource
    Algorithms for the optimal identification of segment neighborhoods (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 39-54 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Two algorithms for the efficient identification of segment neighborhoods are presented. A segment neighborhood is a set of contiguous residues that share common features. Two procedures are developed to efficiently find estimates for the parameters of the model that describe these features and for the residues that define the boundaries of each segment neighborhood. The algorithms can accept nearly any model of segment neighborhood, and can be applied with a broad class of best fit functions including least squares and maximum likelihood. The algorithms successively identify the most important features of the sequence. The application of one of these methods to the haemagglutinin protein of influenza virus reveals a possible mechanism for conformational change through the finding of a break in a strong heptad repeat structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458835
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  • 10
    Electronic Resource
    Electronic Resource
    Approximate matching of regular expressions (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 5-37 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Given a sequenceA and regular expressionR, theapproximate regular expression matching problem is to find a sequence matchingR whose optimal alignment withA is the highest scoring of all such sequences. This paper develops an algorithm to solve the problem in timeO(MN), whereM andN are the lengths ofA andR. Thus, the time requirement is asymptotically no worse than for the simpler problem of aligning two fixed sequences. Our method is superior to an earlier algorithm by Wagner and Seiferas in several ways. First, it treats real-valued costs, in addition to integer costs, with no loss of asymptotic efficiency. Second, it requires onlyO(N) space to deliver just the score of the best alignment. Finally, its structure permits implementation techniques that make it extremely fast in practice. We extend the method to accommodate gap penalties, as required for typical applications in molecular biology, and further refine it to search for substrings ofA that strongly align with a sequence inR, as required for typical data base searches. We also show how to deliver an optimal alignment betweenA andR in onlyO(N+logM) space usingO(MN logM) time. Finally, anO(MN(M+N)+N 2logN) time algorithm is presented for alignment scoring schemes where the cost of a gap is an arbitrary increasing function of its length.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458834
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  • 11
    Electronic Resource
    Electronic Resource
    Codon preference and primary sequence structure in protein-coding regions (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 95-115 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The stochastic complexity of a data base of 365 protein-coding regions is analysed. When the primary sequence is modeled as a spatially homogeneous Markov source, the fit to observed codon preference is very poor. The situation improves substantially when a non-homogeneous model is used. Some implications for the estimation of species phylogeny and substitution rates are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458838
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  • 12
    Electronic Resource
    Electronic Resource
    Tutorial on large deviations for the binomial distribution (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 125-131 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We present, in an easy to use form, the large deviation theory of the binomial distribution: how to approximate the probability ofk or more successes inn independent trials, each with success probabilityp, when the specified fraction of successes,a≡k/n, satisfies 0〈p〈a〈1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458840
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  • 13
    Electronic Resource
    Electronic Resource
    Editorial: Software survey section (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. I 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
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    URL: http://dx.doi.org/10.1007/BF02458844
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  • 14
    Electronic Resource
    Electronic Resource
    A continuous analog for RNA folding (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 167-171 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A linear segment in which a number of pairs of intervals of equal length are identified as potential stems is the subject of a folding problem analogous to inference of RNA secondary structure. A quantity of free energy (or equivalently, energy per unit length) is associated with each stem, and the various types of loops are assigned energy costs as a function of their lengths. Inference of stable structures can then be carried out in the same way as in RNA folding. More important, perturbation of stem lengths and energy densities (modelling various mutational processes affecting nucleotide sequences) allows the delineation of domains of stability of various foldings, through the explicit calculation of their boundaries, in a low-dimensional parameter space.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458842
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  • 15
    Electronic Resource
    Electronic Resource
    Prediction of linear and non-linear responses of MGB neurons by system identification methods (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 337-346 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract In sensory physiology, various System Identification methods are implemented to formalized stimulus-response relationships. We applied the Volterra approach for characterizing input-output relationships of cells in the medial geniculate body (MGB) of an awake squirrel monkey. Intraspecific communication calls comprised the inputs and the corresponding cellular evoked responses—the outputs. A set of vocalization was used to calculate the kernels of the transformation, and these kernels subserved to predict the responses of the cell to a different set of vocalizations. It was found that it is possible to predict the response (PSTH) of MGB cells to natural vocalizations, based on envelopes of the spectral components of the vocalization. Some of the responses could be predicted by assuming a linear transformation function, whereas other responses could be predicted by non-linear (second order) kernels. These two modes of transformation, which are also reflected by a distinct spatial distribution of the linearvis-à-vis non-linear responding cells, apparently representa new revelation of parallel processing of auditory information.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02460112
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  • 16
    Electronic Resource
    Electronic Resource
    Diffusion limited immunochemical sensing (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 359-379 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The time-dependent surface coverage of antigen-antibody complexes for a sensor in which antigens are bound to surface immobilized antibodies is determined analytically. Assuming a reversible first order reaction between the antigens and antibodies, a model is derived describing the dynamical response of the sensor. The surface coverage is related explicitly to the antigen concentration which is of special interest in experimental situations. The stationary state and short time behaviour are determined explicitly. Several illustrations of the full solution are provided.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02460114
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  • 17
    Electronic Resource
    Electronic Resource
    An informational approach to reaction times (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 347-358 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Simple reaction time is the minimum time required to respond to a signal such as a steady light or tone. Such a reaction time is taken to be the time required for transmission of a fixed quantity of information, ΔH, from stimulus to subject. That is, information summation replaces energy summation. This information is calculated from consideration of the quantum nature of the stimulus. The theoretically derived equation for reaction time is fitted to experimental data. Piéron's empirical law for reaction time is obtained as an approximation from a proposed informational equation. The exponent in Piéron's law is found to be the same as the exponent in the power law of sensation. Threshold appears to be the smallest stimulus capable of transmitting the quantity of information ΔH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02460113
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  • 18
    Electronic Resource
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    The Third World Conference on Mathematics at the Service of Man (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 413-413 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02460117
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  • 19
    Electronic Resource
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    Editorial: Software survey section (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. I 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
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    URL: http://dx.doi.org/10.1007/BF02460118
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  • 20
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    The alignment of protein structures in three dimensions (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 55-78 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract This article extends the use of dynamic programming algorithms in molecular sequence comparison to the alignment of the α-carbon (Cα-) coordinates of two protein structures in three dimensions. The algorithm is described in detail and is applied to the comparison of α-lactalbumin with both hen egg white lysozyme and T4 lysozyme. In the first case, the structures are similar, while the second comparison is between two distantly related molecules. References are made to the usual sequence alignments. A variety of complementary methods are introduced to display the results.
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    URL: http://dx.doi.org/10.1007/BF02458836
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  • 21
    Electronic Resource
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    Stochastic models for heterogeneous DNA sequences (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 79-94 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The composition of naturally occurring DNA sequences is often strikingly heterogeneous. In this paper, the DNA sequence is viewed as a stochastic process with local compositional properties determined by the states of a hidden Markov chain. The model used is a discrete-state, discreteoutcome version of a general model for non-stationary time series proposed by Kitagawa (1987). A smoothing algorithm is described which can be used to reconstruct the hidden process and produce graphic displays of the compositional structure of a sequence. The problem of parameter estimation is approached using likelihood methods and an EM algorithm for approximating the maximum likelihood estimate is derived. The methods are applied to sequences from yeast mitochondrial DNA, human and mouse mitochondrial DNAs, a human X chromosomal fragment and the complete genome of bacteriophage lambda.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458837
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  • 22
    Electronic Resource
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    Weak hierarchies associated with similarity measures—An additive clustering technique (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 133-166 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A new and apparently rather useful and natural concept in cluster analysis is studied: given a similarity measure on a set of objects, a sub-set is regarded as a cluster if any two objectsa, b inside this sub-set have greater similarity than any third object outside has to at least one ofa, b. These clusters then form a closure system which can be described as a hypergraph without triangles. Conversely, given such a system, one may attach some weight to each cluster and then compose a similarity measure additively, by letting the similarity of a pair be the sum of weights of the clusters containing that particular pair. The original clusters can be reconstructed from the obtained similarity measure. This clustering model is thus located between the general additive clustering model of Shepard and Arabie (1979) and the standard hierarchical model. Potential applications include fitting dendrograms with few additional nonnested clusters and simultaneous representation of some families of multiple dendrograms (in particular, two-dendrogram solutions), as well as assisting the search for phylogenetic relationships by proposing a somewhat larger system of possibly relevant “family groups”, from which an appropriate choice (based on additional insight or individual preferences) remains to be made.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458841
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  • 23
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    Computational experience with an algorithm for tetrangle inequality bound smoothing (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 173-194 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract An important component of computer programs for determining the solution conformation of proteins and other flexible molecules from nuclear magnetic resonance data are the so-called “bound smoothing algorithms”, which compute lower and upper limits on the values of all the interatomic distances from the relatively sparse set which can usually be measured experimentally. To date, the only methods efficient enough for use in large problems take account of only the triangle inequality, but an appreciable improvement in the precision of the limits is possible if the algebraic relations between the distances among each quadruple of atoms are also considered. The goal of this paper is to use a recently improved algorithm for computing these “tetrangle inequality limits” to determine just how much improvement really is possible, given the types of experimental data that are usually available.
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    URL: http://dx.doi.org/10.1007/BF02458843
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  • 24
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    Wavelength selection mechanism in the Gierer-Meinhardt model (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 207-216 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We apply the concept of marginal stability hypothesis, which has been proposed for solving the problem of dendritic crystal growth, to the pattern selection problem in the Gierer-Meinhardt models. In the case of a large system, the system selects a definite wavelength of the ultimate spatial pattern when the unstable homogeneous steady state is locally disturbed. The numerical results are analyzed theoretically by means of the marginal stability hypothesis, and they are in good agreement with it. Biologically, these results imply why for large systems the Gierer-Meinhardt model (and presumably other reaction-diffusion schemes) have the ability to explain the observation that pattern-generating mechanisms are remarkably insensitive to a wide range of environmental and experimental conditions.
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    URL: http://dx.doi.org/10.1007/BF02458442
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  • 25
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    Automata network theories in immunology: Their utility and their underdetermination (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 247-253 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Small networks of threshold automata are used to model complex interactions between populations of regulatory cells (helpers and suppressors, antigen specific and anti-idiotypic) which participate in the immune response. The models, being discrete and semiquantitative, are well adapted to the situation of incomplete information often encounteredin vivo. However, the dynamics of many different network structures usually end up in the same attractor set. Thus, many different theories are equivalent in their explicative power for the same facts. This property, known as underdetermination of the theories by the facts, is given a quantitative estimate. It appears that such an underdetermination, as a kind of irreductible complexity, can be expected in manyin vivo biological processes, even when the number of interacting and functionally coupled elements is relatively small.
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    URL: http://dx.doi.org/10.1007/BF02458445
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  • 26
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    Resilience and local stability in a nutrient-limited resource-consumer system (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 501-510 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The “paradox of enrichment” predicts that increasing the growth rate of the resource in a resource-consumer dynamic system, by nutrient enrichment, for example, can lead to local instability of the system—that is, to a Hopf bifurcation. The approach to the Hopf bifurcation is accompanied by a decrease in resilience (rate of return to equilibrium). On the other hand, studies of nutrient cycling in food webs indicate that an increase in the nutrient input rate usually results in increased resilience. Here these two apparently conflicting theoretical results are reconciled with a model of a nutrient-limited resource-consumer system in which the tightly recycled limiting nutrient is explicitly modelled. It is shown that increasing nutrient input may at first lead to increased resilience and that resilience decreases sharply only immediately before the Hopf bifurcation is reached.
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    URL: http://dx.doi.org/10.1007/BF02460087
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  • 27
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    Book reviews (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 537-544 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
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    URL: http://dx.doi.org/10.1007/BF02460089
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  • 28
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    Centrifugal-order distributions in binary topological trees (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 511-536 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Statistical properties of topological binary trees are studied on the basis of the distribution of segments in relation to centrifugal order. Special attention is paid to the mean of this distribution in a tree as it will be used as a measure of tree topology. It will be shown how the expectation of the mean centrifugal order depends both on the size of the tree and on the mode of growth in the context of modelling the growth of tree structures. Observed trees can be characterized by their mean orders and procedures are described to find the growth mode that optimally corresponds to these data. The variance structure of the mean-order measure appears to be a crucial factor in these fitting procedures. Examples indicate that mean-order analysis is an accurate alternative to partition analysis that is based on the partitioning of segments over sub-tree pairs at branching points.
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    URL: http://dx.doi.org/10.1007/BF02460088
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  • 29
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    On limits to perception and pattern recognition (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 681-686 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We propose certain general conditions that we believe are reasonable for any pattern recognition algorithm. We find that these conditions give rise to paradoxical identification. The algorithms are incapable of distinguishing composite patterns and must be able to distinguish patterns at an atomistic level.
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    URL: http://dx.doi.org/10.1007/BF02459655
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  • 30
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    Microevolution in MioceneBrizalina (foraminifera) studied by canonical variate analysis and analysis of landmarks (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 657-679 
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    Notes: Abstract A stratigraphically oriented series of the Miocene foraminiferal speciesBrizalina mandoroveensis from Ikang, Cameroon, was analyzed both by conventional multivariate morphometric procedures and by the tensor biometric method of Bookstein (1986;Statist. Sci. 1, 181–142), a method which analyzes sets of landmark points rather than specific variables of shape or size. The conventional analysis used five size-measures upon 170 specimens from five stratigraphic levels; the tensor analysis encompassed six landmarks (12 coordinates) upon 50 specimens. Whereas certain features appeared in both analyses, such as the separation between levels one and five, the techniques did not always agree with respect to the interpretation of those findings or about most details in the sequence of mean phenotypes. The canonical variate analysis bases its ordination upon a general size factor (the meaning of which is obscured by the foreshortening of within-group variation which is built into the technique). The tensor analysis locates a similar ordination using mainly features of shape.
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    Analytic results for quantifying HIV infectivity (1989)
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    Bulletin of mathematical biology 51 (1989), S. 715-730 
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    Notes: Abstract In a separate paper, we developed a mathematical model describing HIV infection and used it to suggest experiments for quantifying characteristic viral parameters. In this paper we generalize the model to any well-mixed assay system. We also present complete and rigorous derivations of fundamental results needed for the design and analysis of HIV infectivity assays. The model is applicable to infectious agents with multiple receptors for their target cell (e.g. HIV, Epstein-Barr virus and Plasmodium), and to blockers (both reversible and irreversible), as long as blocker and target cells are the same diffusion compartment.
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    On Ebenman's model for the dynamics of a population with competing juveniles and adults (1989)
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    Bulletin of mathematical biology 51 (1989), S. 687-713 
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    Notes: Abstract A general version of a model of Ebenman for the dynamics of a population consisting of competing juveniles and adults is analyzed using methods of bifurcation theory. A very general existence results is obtained for non-trivial equilibria and non-negative synchronous two-cycles that bifurcate simultaneously at the critical valuer=1 of the inherent net reproductive rater. Stability is studied in this general setting near the bifurcation point and conditions are derived that determine which of these two bifurcating branches is the stable branch. These general results are supplemented by numerical studies of the asymptotic dynamics over wider parameter ranges where various other bifurcations and stable attractors are found. The implications of these results are discussed with respect to the effects on stability that age class competition within a population can have and whether such competition is stabilizing or destabilizing.
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    Phototransduction in cones: An inverse problem in enzyme kinetics (1989)
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    Bulletin of mathematical biology 51 (1989), S. 749-784 
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    Notes: Abstract Phototransduction is a process which links the absorption of photons by a rod or cone to the modulation of voltage across the cell membrane. An important feature of many vertebrate photoreceptors is a mechanism that adjusts the sensitivity and dynamics of the response to light according to the level of illumination. We construct a system of ordinary differential equations that models what are currently thought to be the important molecule mechanisms involved in phototransduction: this includes consideration of both intracellular enzyme kinetics and the properties of light-insensitive and light-sensitive conductances in the cone membrane. The system contains negative feedback whose functional form is determined by constraining the steady-state behaviour of the system. Despite the highly nonlinear nature of the system of ordinary differential equations, our methods permit us to derive an analytic expression for the first-order frequency response parametric in the steady-state value of only one dynamic variable, the light input. Various unknown kinetic parameters are found by fitting the model to experimental data on the first-order frequency response of cones measured at several mean light levels spanning a range of four log units. Good fits are obtained to the data, and the computed shape of the feedback function agrees qualitatively with recent experiment. Moreover, the model accounts for the dramatic speeding up of the response kinetics and the decrease in response gain with increasing light level.
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    Foreword (1989)
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    Bulletin of mathematical biology 51 (1989), S. 1-4 
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    Unreasonable implications of reasonable idiotypic network assumptions (1989)
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    Bulletin of mathematical biology 51 (1989), S. 381-408 
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    Notes: Abstract We first analyse a simple symmetric model of the idiotypic network. In the model idiotypic interactions regulate B cell proliferation. Three non-idiotypic processes are incorporated: (1) influx of newborn cells; (2) turnover of cells: (3) antigen. Antigen also regulates proliferation. A model of 2 B cell populations has 3 stable equilibria: one virgin, two immune. The twodimensional system thus remembers antigens, i.e. accounts for immunity. By contrast, if an idiotypic clone proliferates (in response to antigen), its anti-idiotypic partner is unable to control this. Symmetric idiotypic networks thus fail to account for proliferation regulation. In high-D networks we run into two problems. Firstly, if the network accounts for memory, idiotypic activation always propagates very deeply into the network. This is very unrealistic, but is an implication of the “realistic” assumption that it should be easier to activate all cells of a small virgin clone than to maintain the activation of all cells of a large (immune) clone. Secondly, graph theory teaches us that if the (random) network connectance exceeds a threshold level of one interaction per clone, most clones are interconnected. We show that this theory is also applicable to immune networks based on complementary matching idiotypes. The combination of the first “percolation” result with the “interconnectancr” result means that the first stimulation of the network with antigen should eventually affect most of the clones. We think this is unreasonable. Another threshold property of the network connectivity is the existence of a virgin state. A gradual increase in network connectance eliminates the virgin state and thus causes an abrupt change in network behaviour. In contrast to weakly connected systems, highly connected networks display autonomous activity and are unresponsive to external antigens. Similar differences between neonatal and adult networks have been described by experimentalists. The robustness of these results is tested with a network in which idiotypic inactivation of a clone occurs more generally than activation. Such “long-range inhibition” is known to promote pattern formation. However, in our model it fails to reduce the percolation, and additionally, generates semi-chaotic behaviour. In our network, the inhibition of a clone that is inhibiting can alter this clone into a clone that is activating. Hence “long-range inhibition” implies “long-range activation”, and idiotypic activation fails to remain localized. We next complicate this model by incorporating antibody production. Although this “antibody” model statically accounts for the same set of equilibrium points, it dynamically fails to account for state switching (i.e. memory). The switching behaviour is disturbed by the autonomous slow decay of the (long-lived) antibodies. After antigenic triggering the system now performs complex cyclic behaviour. Finally, it is suggested that (idiotypic) formation of antibody complexes can play only a secondary role in the network. In conclusion, our results cast doubt on the functional role of a profound idiotypic network. The network fails to account for proliferation regulation, and if it accounts for memory phenomena, it “explodes” upon the first encounter with antigen due to extensive percolation.
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    Description of the birch leaf roller's incisions for different leaves (1989)
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    Bulletin of mathematical biology 51 (1989), S. 433-447 
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    Notes: Abstract A new biomathematical description is given for the shape of the birch leaf roller's (Deporaus betulae) incisions. These incisions are investigated for different leaves. The theoretical patterns agree well with the real ones, and the presented mathematical expressions describe well the shape of the real incisions.
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    The multiple codes of nucleotide sequences (1989)
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    Bulletin of mathematical biology 51 (1989), S. 417-432 
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    Notes: Abstract Nucleotide sequences carry genetic information of many different kinds, not just instructions for protein synthesis (triplet code). Several codes of nucleotide sequences are discussed including: (1) the translation framing code, responsible for correct triplet counting by the ribosome during protein synthesis; (2) the chromatin code, which provides instructions on appropriate placement of nucleosomes along the DNA molecules and their spatial arrangement; (3) a putative loop code for single-stranded RNA-protein interactions. The codes are degenerate and corresponding messages are not only interspersed but actually overlap, so that some nucleotides belong to several messages simultaneously. Tandemly repeated sequences frequently considered as functionless “junk” are found to be grouped into certain classes of repeat unit lengths. This indicates some functional involvement of these sequences. A hypothesis is formulated according to which the tandem repeats are given the role of weak enhancer-silencers that modulate, in a copy number-dependent way, the expression of proximal genes. Fast amplification and elimination of the repeats provides an attractive mechanism of species adaptation to a rapidly changing environment.
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    Velocity distribution on the membrane of a tank-treading red blood cell (1989)
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    Bulletin of mathematical biology 51 (1989), S. 449-465 
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    Notes: Abstract The kinematics of an area-conserving tank-treading disk-shaped red blood cell membrane is studied using the stream function method suggested by Secomb and Skalak (Q. Jl Mech. appl. Math. 35, Pt 2, 233–247, 1982). Two simple area-conserving velocity fields are superimposed to satisfy the continuity condition at the curved edges of the disk. A differential equation for the trajectory of any material point of the membrane is derived. The requirement of synchrony of the cycle for all membrane points leads to an integral equation which determines a magnitude function. An approximate solution is made possible by assuming small trajectory deflections.
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    Mathematical formulation and studies of the risk parameters involved in HIV transmission (1989)
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    Bulletin of mathematical biology 51 (1989), S. 467-474 
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    Notes: Abstract The probability of becoming infected with HIV is formulated in terms of the total number of sexual contacts (N), the probability that a sexual act is infectious (r) and the prevalence (p). Using the appropriate equations we studied the effect of reducing each of the risk factors on lowering the probability of infection. We show that for many realistic situations the probability of becoming infected by multiple partners is equal to the probability of becoming infected by one partner in a monogamous relationship given that the prevalence is the same in both cases; however if the multiple partners are chosen over time from a pool of a growing prevalence, then one is better off in a monogamous relationship where that partner is chosen early in the epidemic.
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    An optimal algorithm to reconstruct trees from additive distance data (1989)
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    Bulletin of mathematical biology 51 (1989), S. 597-603 
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    Notes: Abstract In this article the question of reconstructing a phylogeny from additive distance data is addressed. Previous algorithms used the complete distance matrix of then OTUs (Operational Taxonomic Unit), that corresponds to the tips of the tree. This usedO(n 2) computing time. It is shown that this is wasteful for biologically reasonable trees. If the tree has internal nodes with degrees that are bounded onO(n*log(n)) algorithm is possible. It is also shown if the nodes can have unbounded degrees the problem hasn 2 as lower bound.
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    Editorial: Software survey section (1989)
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    Bulletin of mathematical biology 51 (1989), S. I 
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    Temporal properties of some biological systems and their fractal attractors (1989)
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    Bulletin of mathematical biology 51 (1989), S. 785-800 
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    Notes: Abstract In this paper we analyse time series data as the growth of organisms using markers such as treerings and otolith deposits (fish). The series studied belong to two tree species (Pinus uncinata, Fagus sylvatica) and one fish species (Dicentrarchus labrax). Spectral analyses of the time series growth show that the main frequencies of fluctuation may be due to variations of the energy input. However, any causal explanation must consider the internal continuous readjustment in the system as reported by the corresponding chaotic properties of the asymptotic decay of the spectra time structure. Since the output of noisy and chaotic systems tend to show similar spectral densities, an attempt to differentiate them has been carried out. The chaotic behaviour has been characterized by the study of the attractors. The dimmensions of these multiple topologies were 3.2 and 3.4 for the tree species and 2.3 for the fish species. Therefore, we are dealing with fractal attractors and the minimum number of variables that can be used to describe the systems are 4 and 3 respectively. It is suggested that some of the variables that most influence growth are those obtained by the response functions in the case of trees.
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    Context-dependent associations in linear distributed memories (1989)
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    Bulletin of mathematical biology 51 (1989), S. 195-205 
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    Notes: Abstract In this article we present a method that allows conditioning of the response of a linear distributed memory to a variable context. This method requires a system of two neural networks. The first net constructs the Kronecker product between the vector input and the vector context, and the second net supports a linear associative memory. This system is easily adaptable for different goals. We analyse here its capacity for the conditional extraction of features from a complex perceptual input, its capacity to perform quasi-logical operations (for instance, of the kind of “exclusive-or”), and its capacity to structurate a memory for temporal sequences which access is conditioned by the context. Finally, we evaluate the potential importance of the capacity to establish arbitrary contexts, for the evolution of biological cognitive systems.
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    Stability of symmetric idiotypic networks—a critique of Hoffmann's analysis (1989)
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    Bulletin of mathematical biology 51 (1989), S. 217-222 
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    Notes: Abstract Hoffmann (1982) analysed a very simple model of suppressive idiotypic immune networks and showed that idiotypic interactions are stabilizing. He concluded that immune networks provide a counterexample to the general analysis of large dynamic systems (Gardner and Ashby, 1970; May, 1972). The latter is often verbalized as: an increase in size and/or connectivity decreases the system stability. We here analyse this apparent contradiction by extending the Hoffmann model (with a decay term), and comparing it to an ecological model that was used as a paradigm in the general analysis. Our analysis confirms that the neighbourhood stability of such idiotypic networks increases with connectivity and/or size. However, the contradiction is one of interpretation, and is not due to exceptional properties of immune networks. The contradiction is caused by the awkward normalization used in the general analysis.
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    An alternative procedure for calculating glucose consumption from 2-deoxyglucose uptake (1989)
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    Bulletin of mathematical biology 51 (1989), S. 275-286 
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    Notes: Abstract In the commonly used model (Sokoloff) for the transport and metabolism of glucose and 2-deoxyglucose in brain tissue a novel choice of constant parameters is proposed. In particular, the maximal transport capacity for glucose is assumed proportional to the rate of glucose consumption. The proportionality factor, the “transport factor”, may be calculated from the lumped constant and is more likely than the latter to remain constant under varying conditions. Calculations founded on these considerations should yield results similar to the Sokoloff procedure in many situations, but differences appear when the arterial glucose concentration changes. The model is flexible and allows changes.
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    Analysis of metabolic systems with complex slow and fast dynamics (1989)
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    Bulletin of mathematical biology 51 (1989), S. 255-274 
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    Notes: Abstract We briefly review the results of other authors concerning the analysis of systems with time hierarchy, especially the Tikhonov theorem. A theorem, recently proved by the authors, making possible rigorous analysis of systems with complex fast dynamics is stated and discussed. A model example of a simple enzymatic reaction with product activation and slow (genetically driven) enzyme turnover is rigorously studied. It is shown that even in such a simple model there exist certain regions of parameters for which fast variables oscillate. Thus the classical Tikhonov theorem is not applicable here and we are forced to use another method-for example the author's presented theorem—or a purely numerical solution. These two methods are compared.
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    Analysis of interaction for mixtures of agents using the linear isobole (1989)
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    Bulletin of mathematical biology 51 (1989), S. 293-309 
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    Notes: Abstract The linear isobole that is commonly used as a reference for the study of interaction is derived from the interaction of an agent with itself. It is shown that the general use of the linear isobole in the study of the combined effects of mixtures of agents implies interaction between the agents whether the dose-effect curves of the agents are the same or not. It is difficult to generalize the interaction between two doses of the same agent to the interaction between two doses of different agents with different action mechanisms without the use of a mechanistic model. Predictions using non-interaction defined as independent action are generally different from those using linear isobole. A simple mechanistic framework based on the concept of common intermediate lesions is introduced in this paper to relate these two methods used for the analysis of synergism and antagonism. In this framework of lesion development, two agents that have no common intermediate lesion in their action will be non-interactive (referred to as independent action). When the two agents share a common intermediate, it is shown that the combined effect will follow the linear isobole (referred to as common action). This simple framework of analysis is applicable to the general study of interaction between two agents with different types of dose-effect curves.
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    Probabilistic models of genome shuffling (1989)
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    Bulletin of mathematical biology 51 (1989), S. 117-124 
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    Notes: Abstract The comparison of entire genomes in evolutionary studies gives rise to alignments characterized by many intersections, or inversions in the order of two fragments in different genomes. To model this, we suggest a random migration process for fragments, and discuss its equilibrium distribution in the case of linear and circular genomes. Simulations are carried out to explore “cut-off” behavior as the process approaches equilibrium. We define a new process to take into account the indistinguishability of two fragments which are adjacent in both genomes being compared. Questions of applicability of these models are discussed.
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    Some applications of theP-V relation to the study of left ventricular performance (1989)
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    Bulletin of mathematical biology 51 (1989), S. 475-484 
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    Notes: Abstract There is still controversy as to which characteristics of the pressure-volume relation should be used to define myocardial contractility. In the present study a mathematical model for the left ventricle as a two-dimensional cylinder contracting radially and symmetrically was used to establish a relation between a calculated intramyocardial pressure (Dh) and theP-V relation (PVR) at end-systole. Four new indices are introduced that allow a better assessment of change in inotropic state of the myocardium, namely the calculated intramyocardial pressure (Dh), the calculated resultant pressure across the inner surface of the myocardium (Dh-P) (P=cavity pressure), the workW t related to the pressure (Dh) and the workW d related to the pressure (Dh-P). A relation betweenW t andW d and different parts of the area under the PVR is established. Indices derived in this manner from the PVR to study changes in myocardial contractility appear to have a clear physical meaning.
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    A mathematical model for cell sorting, migration and shape in the slug stage ofDictyostelium discoideum (1989)
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    Bulletin of mathematical biology 51 (1989), S. 485-500 
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    Notes: Abstract A mathematical model for cell sorting and migration in the slug stage of cellular slime moldsDictyostelium discoideum is proposed. Assuming that a slug is a “mixed fluid” of prespore and prestalk cells, a set of equations which describe the dynamics of cell distribution, internal pressure and velocity of hte slug are derived from the balance formula of individual cell movement. These equations are analyzed to obtain the spatial patterns of the two types of cells at dynamical equilibrium and the relationship between the migration velocity and the slug size. The body shape of the elongated slug at the migrating stage is also investigated, taking account of the law of surface tension. The stable shapes of slugs with different volumes are explicity obtaained and the existence of critical size of a slug is suggested.
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    Announcement (1989)
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    Bulletin of mathematical biology 51 (1989), S. 545-546 
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    Editorial: Software survey section (1989)
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    Bulletin of mathematical biology 51 (1989), S. I 
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    Editorial (1989)
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    Bulletin of mathematical biology 51 (1989), S. 547-547 
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    A cascading development model for amphibian embryos (1989)
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    Bulletin of mathematical biology 51 (1989), S. 549-578 
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    Notes: Abstract The mesodermal tissue of some amphibian gastrula develops into a dorsal-to-ventral sequence of notochord, somite, pronephros, and lateral plate cell types. The cellular proportions regulate with respect to embryo size. The dorsal blastoporal lip appears to function as an organizer for the embryo. The transplantation of a donor lip to the ventral side of a host causes a second, opposed embryo to form and the system commits similar total proportions of cells as do normally developing embryos. Transplantation of donor somite to the ventral side of a host causes a reduction in the proportion of host somite developed. A modified reaction-diffusion system governing embryo development is proposed. Developmental simulations consistent with experimental observations are presented and analyzed. The results suggest that the degree of somite inhibition is positively correlated with the size of the somite transplant. Further predictions are that sufficiently large somite transplants would induce ectopic, ventral pronephros to form and ventral pronephros transplants would inhibit host pronephros development.
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    Modelling autonomous oscillations in the human pupil light reflex using non-linear delay-differential equations (1989)
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    Bulletin of mathematical biology 51 (1989), S. 605-624 
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    Notes: Abstract Neurophysiological and anatomical observations are used to derive a non-linear delay-differential equation for the pupil light reflex with negative feedback. As the gain or the time delay in the reflex is increased, a supercritical Hopf bifurcation occurs from a stable fixed point to a stable limit cycle oscillation in pupil area. A Hopf bifurcation analysis is used to determine the conditions for instability and the period and amplitude of these oscillations. The more complex waveforms typical of the occurrence of higher order bifurcations were not seen in numerical simulations of the model. This model provides a general framework to study the different types of dynamical behaviors which can be produced by the pupil light reflex, e.g. edge-light pupil cycling.
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    Two exceptional sets of physiological clearance curves and their mathematical form: Test cases? (1989)
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    Bulletin of mathematical biology 51 (1989), S. 579-596 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Amiodarone concentrationsy(t) have been measured from 1 min to more than 50 days following 10 min of infusion, with about 40 observations on each of six normal subjects (Tuckeret al., 1984,Eur. J. clin. Pharmacol. 26, 655–656). The form of the log-log plots—ln(y) vs ln(t)—is investigated. These appear to show three phases. First there is a rapid decrease ofy(t). then a straight line corresponding to a small negative power oft, ca −0.3, and this line changes continuously but quickly at about 0.5 day into a steeper line that is almost straight. For the curve fitting a simple “spline-type” device was successful. Two continuity conditions were imposed at the time of changeover, which was one of the unknown parameters. The results are compared in detail with those from a set of 15 radiocalcium curves obtained during 2 weeks or more from a single injection of47Ca (Neeret al., 1967,J. clin. Invest. 46, 1364–1379). Again two power functions of time can be seen. The changeover is much more gradual than with amiodarone, and the fits are still better. Both sets of curves are fitted with fewer adjustable parameters than with the usual multiexponentials that are interpreted in terms of homogeneous compartments. Theoretical and practical implications are mentioned. There is much indirect evidence that hundreds of other clearance curves may consist largely of one or two of such power functions of time.
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    Stationary distribution of population size inTribolium (1989)
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    Bulletin of mathematical biology 51 (1989), S. 625-638 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We propose the use of a stationary probability distribution for the analysis of data on population size. Predicting this long term population property from short term individual events is accomplished by the use of the asymptotic theory of stochastic processes. A WKB approximation to the stationary density is obtained and then applied to observations on the flour beetleTribolium.
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    Editorial: Software survey section (1989)
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    Bulletin of mathematical biology 51 (1989), S. I 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
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    Book reviews (1989)
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    Bulletin of mathematical biology 51 (1989), S. 639-655 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
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    Book reviews (1989)
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    Bulletin of mathematical biology 51 (1989), S. 801-809 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
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    URL: http://dx.doi.org/10.1007/BF02459661
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    Interaction of media components during bioreactor sterilization: definition and importance of R0 (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 247-252 
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    ISSN: 1476-5535
    Keywords: Sterilization ; Bioreactor ; Media ; R0 ; F0
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Sterilization of bioreactor media, to destroy viability of the indigenous microbial population, is normally accomplished by autoclaving, or heating with pressurized steam. However, simultaneous chemical changes in media can also be expected to result from the high temperatures. A kinetic procedure involving on-line computer calculation of heat input, designated asF 0 values, was previously developed to estimate sterility achievement. A similar kinetic procedure, based on a general purpose Arrhenius ‘pseudo’ rate equation and designated asR 0 values, has now been designed to evaluate, and control the effects of temperature and heating time on chemical reactions occurring in the media. Data are presented indicating thatR 0 may be a useful parameter for reducing variability in culture metabolism and ‘scale-up’ when these variations result from different nutrient concentrations produced by non-standard heating during media sterilization in stirred bioreactors.
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    Altered bacterial culture density following exposure to aflatoxins (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 275-278 
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    ISSN: 1476-5535
    Keywords: Aflatoxin ; Bioassay ; Cell growht ; Bacterium ; Density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Eight species of bacteria were incubated in culture media containing 10 μg/ml aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), or aflatoxin G2 (AFG2). Their culture density at 20°C was determined at four and eight days (d) after inoculation. In all species of bacteria studied (Bacillus cereus, Proteus mirabilis, Erysipylothrix rusiopathie (insidiosa), Streptococcus fecalis, Staphylococcus epidermis, Klebsiella pneumoniae, Micrococcus spp., andEscherichia coli), AFB1, AFB2 and AFG2 substantially decreased culture sizes at 4 d, but not at 8 d. InB. cereus andP. mirabilis, culture sizes were increased by AFB1, AFB2, and AFG2 at 8 d post inoculation. These results indicate that AFB1, AFB2, and AFG2 suppressed initial growth of these species in vitro, while later growth in some species was either unaltered or enhanced.
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    Germanium toxicity in selected bacterial and yeast strains (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 299-306 
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    ISSN: 1476-5535
    Keywords: Bioaccumulation ; Germanium ; Sensitivity ; Tolerance ; Toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The toxicity of germanium dioxide (GeO2) to 21 bacterial and 13 yeast strains was investigated in liquid broth medium to obtain information on strains tolerant to high (1 to 2 mg/ml) GeO2 concentrations.Arthrobacter sp. NRC 32005,enterobacter aerogenes NRC 2926,Klebsiella aerogenes NCTC 418 andPseudomonas putida NRC 5019 were tolerant to 1 mg/ml GeO2.Bacillus sp. RC607 was able to grow in the presence of 2 mg/ml GeO2 at pH 10 in broth culture. The yeastsCandida guilliermondii, Candida shehatae andPachysolen tannophilus were the most sensitive to GeO2 as evidenced by their diminished growth rates at a GeO2 concentration as low as 0.1 mg/ml. None of the yeast strains tested exhibited growth in the presence of 1 mg/ml GeO2. The high pH of the medium containing germanium may be partially responsible for the growth inhibition of the yeast cultures. Select bacterial cultures previously exposed to 1 mg/ml GeO2 could tolerate and grow better at 2 mg/ml GeO2, suggesting the existence of very efficient adaptive mechanisms. The pH of the medium could modulate GeO2 tolerance and this effect was found to be strain-dependent.
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    Protoplast formation, L-colony growth, and regeneration ofClostridium beijerinckii NRRL B-592 and B-593 andClostridium acetobutylicum ATCC 10132 (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 325-331 
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    ISSN: 1476-5535
    Keywords: Clostridium genetics ; Clostridium beijerinckii ; Clostridium acetobutylicum ; Protoplast regeneration ; L-colony
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Protocols for protoplast formation, L-colony cultivation, and regeneration ofClostridium beijerinckii NRRL B-592, B-593 andC. acetobutylicum ATCC 10132 were developed. Two osmotically reinforced media were formulated. Protoplasts of B-592, B-593, and ATCC 10132 grew as cell wall-deficient forms (L-colonies) when plated on the first medium (BLM) and continued to do so through at least 3 passages on this medium. The second (BRM) permitted the L-colonies to regenerate cell walls after transfer to this medium. TransferredC. beijerinckii B-592 L-colonies reverted to bacillary colonies at a frequency of 25%. Likewise, L-colonies of B-593 andC. acetobutylicum ATCC 10132 could be regenerated at frequencies of 7.0 and 8.6%, respectively. Thus, these procedures are suitable for genetic engineering of these industrial microorganisms using protoplast manipulation techniques.
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    Purification and properties of xylanase fromAureobasidium (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 341-347 
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    ISSN: 1476-5535
    Keywords: Auerobasidium ; Color variants ; Xylanase ; Hemicellulase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The yeast-like fungusAureobasidium is a promising source of xylanase (EC 3.2.1.8) with an exceptionally high specific activity. For enzyme production in volumes of several liters, xylose was the preferred carbon source and inducer. Xylanase in clarified cultures was concentrated by reversible adsorption to cation-exchange matrix to 5% of the initial volume, and recovered at nearly 2 million IU/1. Selective conditions permitted 97% recovery of xylanase with a 1.8-fold enrichment in specific activity, to 70% of purity. The predominant xylanase species (20 kDa) was subsequently purified to 〉99% of homogeneity by gel filtration chromatography. Purified enzyme exhibited an isoelectric point of 8.5, and specific activity of 2100 IU/mg under optimal conditions, determined to be pH 4.5 and 45°C. The activity of purified enzyme was specific for polymeric xylan.
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    Toxic effects of tin compounds on microorganisms (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 375-402 
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    ISSN: 1476-5535
    Keywords: Toxicity ; Organotins ; Tin ; Methiltins ; Butyltins ; Tributyltin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Organotins are used for industrial and agricultural purposes and in antibiologic agents. They are significantly more toxic than inorganic tins, and eventually reach the environment where they can be toxic to a wide variety of organisms. Particular attention has been given to tributyltins which are highly toxic components of antifouling paints. Realization that the molecular species of organotin influences fate and effects of organotins led to development of sensitive methods for quantifying individual molecular species. Even though such methods are now available, little information has been obtained on the ability of microorganisms to bioaccumulate tin compounds. Trisubstituted alkyl and aryltins (R3Sn's) are more toxic than disubstituted compounds (R2Sn's) while monosubstituted organotins (RSn's) are still less toxic. R4Sn's are toxic only if they are metabolized to R3Sn's. Among trisubstituted compounds propyl-, butyl-, pentyl-, phenyl-, and cyclohexyl Sn's are generally the most toxic to microorganisms. Toxicity in the R3Sn series is related to total molecular surface area of the tin compound and to the octanol:water partition coefficient,K ow, which is a measure of hydrophobicity; a highK ow indicates greater hydrophobicity and predicts greater toxicity. Care must be taken when testing the toxicity of tin compounds, for a number of biological, physical and chemical factors can influence the apparent toxicity. Although little is known of the effects of tin compounds on microbial processes, a number of bacterial processes can be inhibited by organotins and all relate to membrane functions. They include effects on energy transduction, solute transport and retention and oxidation of substrates. Very little is known of how organotins exert their toxic effects on algae and fungi; Information on effects on chloroplasts and mitochondria stems principally from animal systems and from higher plants. Triorganotins act against chloroplasts and mitochondria by causing swelling, by acting as ionophores and by acting against ATPase, while diorganotins appear to act by binding to dithiol groups on enzymes and cofactors. Nucleic acids do not seem to be affected at environmentally relevant concentrations. Virtually nothing is known of the action of tin compounds on microbial enzymes, but resistant mutants are easy to obtain and should facilitate work to understand modes of microbial interaction with tin compounds and mechanisms of resistance.
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    Enzymatic characterization ofBacilli from food packaging paper and board machines (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 419-428 
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    ISSN: 1476-5535
    Keywords: Bacillus ; Paper and board machines ; Starch degrading enzymes ; Cellulase ; Proteases ; Slimicides ; Food packaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Aerobic spore-forming bacteria were found dominant in the microflora of food packaging paper and board. Twenty-five strains of bacteria belonging to the genusBacillus were isolated from these paper and board machines, papermaking chemicals, and final products of papermaking. Nineteen strains were analyzed for production of α-amylase, α-glucosidase, glucoamylase, pullulanase, β-glucanase, carboxymethyl cellulase, and caseinase, and also for resistance towards industrial biocides. pH and temperature optima for the activity of the enzymes were determined. All strains were found to produce one or more of the enzymes studied. The amylolytic enzymes of most strains had high temperature optima for activity. Vegetative cells of all strains were found very resistant towards the different commercial slimicides used in paper and board mills. This property together with the ability to survive through the dry end of the machine to the final board and paper, and the production of enzymes degrading papermaking chemicals makes these bacteria potentially harmful in paper and board mills.
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    Monitoring genetically engineered microorganisms in freshwater microcosms (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 441-446 
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    ISSN: 1476-5535
    Keywords: DNS hybridization ; Gene probe ; Environmental survival ; Pseudomonas cepacia AC1100 ; Alcaligenes A5
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The effectiveness of gene probe methods for tracking genetically engineered microorganisms (GEMs) in the environment was tested by inoculating nutrient-supplemented freshwater microcosms withAlcaligenes A5 (a naturally occurring 4-chlorobiphenyl degrader) orPseudomonas cepacia AC1100 (a genetically engineered 2, 4, 5 T-degrader) and following the fates of the introduced bacterial populations. Colony hybridization of the viable heterotrophic bacterial populations and dot blot hybridization of DNA recovered from the total microcosm microbial communities showed persistence of bothAlcaligenes A5 andP. cepacia AC1100 in the microcosms in the presence and absence of the xenobiotic substrates that these organisms biodegrade. Although there was a gradual decline in the added populations, both of the bacterial populatins were still detected in the microcosms two months after their introduction into the microcosms. Addition of 2, 4, 5-T enhanced the survival ofP. cepacia AC1100 — and 4-chlorobiphenyl addition resulted in increased levels ofAlcaligenes A5. The results indicate that both organisms may persist for very long periods in freshwater habitats.
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    The mechanism of stabilization of actinomycete foams and the prevention of foaming under laboratory conditions (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 181-187 
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    ISSN: 1476-5535
    Keywords: Nocardia amarae ; Surface tension ; Hydrocarbon affinity ; Montmorillonite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Cultures ofNocardia amarae give rise to cell-stabilized foams in a laboratory scale foaming apparatus. The organism produces a surfactant and the cells are very hydrophobic; factors which, in terms of froth flotation theory, are essential for foam production and transport of the cells from the aqueous to the bubble phase. The addition of montmorillonitic clay to the culture prior to foaming prevents foam stabilization. The results obtained suggest the formation of a salt-dependent, reversible, bacterium-montmorillonite complex which prevents transport of cells to the bubble phase.
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    Influence of coal source and treatment upon indigenous microbial communities (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 195-207 
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    ISSN: 1476-5535
    Keywords: Coal leaching ; Desulfurization ; Thiobacilli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The leaching of six Eastern coals was investigated using experimental coal columns subjected to simulated leaching events. Measurements of CO2 assimilation and specific enrichment cultures indicated that the microbial communities of all leachates were dominated by iron- and sulfur-oxidizing chemoautotrophic bacteria. Comparison of CO2 assimilation rates in leachates and core samples of leached coal indicated that most chemoautotrophs remained within coal columns during leaching. Mean numbers of chemoautotrophic bacteria in leachate samples were correlated with concentrations of dissolved iron and sulfate. Leachates from unwashed, run-of-mine coals contained more chemoautotrophs and more iron and sulfate than did leachates from washed, final product coals. After several leachings, the ratio of sulfur oxidizers to iron oxidizers tended to increase. These data suggest that the chemoautotrophic community of final product coals may be pyritelimited. Aerobic heterotrophs constituted a minor component of the microbial community in leachates from the six coals and their abundance and metabolic activity were apparently not influenced by the beneficiation history of the coal. Changes in rates of acetate metabolism may have been related to microbial succession within the heterotrophic community of coal columns. In all leachates, rates of tritiated methylthymidine assimilation were correlated with rates of acetate incorporation but not with CO2 assimilation, even though autotrophs dominated the microflora. Thus, thymidine assimilation rates appear to reflect activities or growth of mainly heterotrophic microorganisms in leachate.
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    Effects of immobilization on growth, substrate consumption, β-galactosidase induction, and byproduct formation inEscherichia coli (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 239-246 
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    ISSN: 1476-5535
    Keywords: Metabolism ; Acetate ; Alginate ; Carbon balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Some metabolic properties of both suspended and immobilized aerobically and anaerobically growingEscherichia coli cells were investigated. Metabolic activity was found to be substantially different whenE. coli cells were immobilized in alginate. Cells grown immobilized in alginate, and then released from the gel, synthesized 1.6 (aerobic growth) and 4.9 (anaerobic growth) times as much β-galactosidase per cell in response to induction as did suspended cells. Under both aerobic and anaerobic conditions, the cell yield from glycerol for immobilized cells was half that for suspended cells. At specific growth rates that were not significantly different from those of suspended cells, immobilized cells consumed glycerol at twice the rate of suspended cells. Immobilized cells produced elevated quantities of acetate, pyruvate, and lactate. Interpretation of these findings is discussed in terms of the kinetics of energy metabolism and the regulation of inducible protein synthesis inE. coli.
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    Fructose production by immobilizedArthrobacter cells (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 267-274 
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    ISSN: 1476-5535
    Keywords: Glucose isomerase ; Immobilization ; K-carrageenan ; Glucose ; Fructose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary ImmobilizedArthrobacter cells (NRRL-B-3728) were used for continuous isomerization of glucose to fructose in a bioreactor system. The system utilized stationary phase (55h) cells (2.2×109 CFU/ml saline) immobilized onto K-carrageenan (3% w/v) beads [cells were heated at 65°C for 10 min to inactivate endogenous proteolytic enzymes]. Immobilized-cell preparations were hardened using three different glutaraldehyde systems. Glutaraldehyde (0.2 M) treated-immobilized cells (pH 7.0, 5°C for 30 min) exhibited good gel strength and high glucose isomerase activities. Maximal bioreactor isomerization of 44% was achieved when a buffered feedstock containing 40% glucose was fed into the column (60°C) at a flow rate of 0.2 ml/min. The biological half-life of glucose isomerase activities in this system was 400 h. Scanning electron microscopy revealed large numbers of cells distributed within the beads. A thin layer surrounding the beads following glutaraldehyde treatment was mainly due to cross-linking reactions between cell proteins and glutaraldehyde. This layer prevented leaking of cells during continuous isomerization reaction.
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    Biodegradation of a dilute waste oil emulsion applied to soil (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 289-298 
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    ISSN: 1476-5535
    Keywords: Biodegradation ; Landfarming ; Metal-working coolants ; Waste-oil emulsions ; On-site oil disposal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The use of land treatment for disposal of a dilute waste oil emulsion generated by an aluminum rolling industry was investigated. Major components of the waste, identified by gas chromatography and mass spectrometry, were linear and branched (C12−C25) and fatty acid emulsifiers (primarily, isomers of oleic acid). Hexadecane and pristane were readily biodegraded in vitro when added to soil collected from the waste disposal site. Hydrocarbons and fatty acids extracted from the waste were similarly, biodegraded, however, the rate of decomposition may have depended on the history of waste applications to soil collected from the land treatment site. The apparent half-life of resolvable waste hydrocarbons and fatty acids was 9.5 days in soil which had received waste applications averaging 25.4l m−2 wk−1. In contrast, soil receiving either 50.8l m−2 wk−1 or no waste application during summer 1987 apparent exhibited half-lives of 28.1 and 60.3 days, respectively. Waste components were restricted to the upper 48 cm of the soil cores collected from the disposal site. Core samples also provided evidence for biodegradation of hydrocarbons and fatty acids as well as an accumulation of other compounds not readily resolvable by gas chromatography
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    Sugar utilization by yeast during fermentation (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 315-323 
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    ISSN: 1476-5535
    Keywords: Sugar uptake ; Yeast ; Brewer's wort
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary When glucose and fructose are fermented separately, the uptake profiles indicate that both sugars are utilized at similar rates. However, when fermentations are conducted in media containing an equal concentration of glucose and fructose, glucose is utilized at approximately twice the rate of fructose. The preferential uptake of glucose also occurred when sucrose, which was first rapidly hydrolyzed into glucose and fructose by the action of the enzyme invertase, was employed as a substrate. Similar results were observed in the fermentation of brewer's wort and wort containing 30% sucrose and 30% glucose as adjuncts. In addition, the high levels of glucose in the wort exerted severe catabolite repression on maltose utilization in theSaccharmyces uvarum (carlsbergensis) brewing strain. Kinetic analysis of glucose and fructose uptake inSaccharomyces cerevisiae revealed aK m of 1.6 mM for glucose and 20 mM for fructose. Thus, the yeast strain has a higher affinity for glucose than fructose. Growth on glucose or fructose had no repressible effect on the uptake of either sugar. In addition, glucose inhibited fructose uptake by 60% and likewise fructose inhibited, glucose uptake by 40%. These results indicate that glucose and fructose share the same membrane transport components.
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    Efficacy of bromochlorodimethylhydantoin againstLegionella pneumophila in industrial cooling water (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 403-408 
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    ISSN: 1476-5535
    Keywords: Bromochlorodimethylhydantion ; Legionella pneumophila ; Industrial cooling water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Free residual chlorine and bromine can be generated in water from bromochlorodimethylhydantoin (BCDMH). Efficacy of chlorine from inorganic sources has been studied extensively, but there is much less information on the efficacy of bromine againstL. pneumophila; only a few efficacy studies of organically-derived. halogen appear in the literature and the results from different studies conflict or are difficult to interpret. This paper describes the efficacy of halogen from BCDMH against planktonic, pure cultureL. pneumophila in an industrial cooling water. There was no difference in efficacy between halogen derived from organic or inorganic sources in controlled laboratory experiments. Effective doses in laboratory studies cannot be translated directly to field applications because of significant differences in the microbiology. However, the data suggest that disinfection (〉99.9% reduction in viability within 10 min) of planktonic, pure cultureL. pneumophila can be achieved with about 1 ppm free residual halogen (expressed as chlorine) from BCDMH in a typical industrial cooling water.
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    Substrate specificity, de novo synthesis and partial purification of polyphenol oxidase derived from the wood-decay fungus,Coriolus versicolor (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 349-363 
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    ISSN: 1476-5535
    Keywords: Coriolus versicolor ; Wood-decay fungus ; Polyphenol oxidase ; Substrate specificity ; de novo Synthesis ; Partial purification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Coriolus versicolor, a white-rot Basidiomycete, secretes cellulolytic and ligninolytic enzymes as well as polyphenol oxidase (PPO). Whereas the former degrade wood polymers, the latter can convert diphenols to diquinones and oligomerize syringic acid, a lignin derivative. Certain phenolic compounds can serve as disease-resistance factors controlling the proliferation of wood-decay fungi within host tissues. BecauseC. vesicolor can be ‘batch-cultured’, overproduction and enhanced secretion of enzymes of biological and commercial interests are feasible. Reported here are the results of attempts to define the timed appearances of intracellular and extracellular PPO, to assess substrate specificity as well as distinguish synthesis versus activation of intracellular PPO and to partially purify extracellular PPO. These efforts were to provide data enabling cell-free synthesis of PPO, cloning of the gene(s) for the oxidase and the establishment of its subcellular route of secretion. Whereas two protein peaks (6 and 12 days in a 16 day time-course) were observed for dialyzed mycelial homogenates, the homogenates' PPO specific activity rose between 4 and 12 days and then declined. Total extracellular protein content climbed from 6 to 15 days for dialyzed growth medium and the medium's PPO specific activity rose at 4 days post-inoculation and except at 9 days increased linearly to 15 days. When aliquots of dialyzed 12 and 15 day media were added to PPO assay mixtures containing catechol and either syringic or gallic acids, statistically significant differences in PPO specific activity between phenolic substrates were noted. Supplementation of cultures with 1.91 μg cycloheximide ml growth medium−1 (control, growth medium only) together with 0.5 μCi [14C]-leucine revealed that cycloheximide inhibited PPO activity and suppressed [14C]-leucine incorporation into TCA-insoluble cytoplasmic protein. As for PPO partial purification, growth medium dialysis followed by 0–30% (NH4)2SO4 fractionation and subsequent 12 000×g dialyzate centrifugation yielded a 3.27-fold enhancement in PPO specific activity within the 12 000×g supernatant. Chromatography of the latter upon DEAE-Sephadex indicated that PPO exchanged with the DEAE counterion as it could be eluted with high ionic strength salt. These results suggest that: the occurrences of intracellular and extracellular PPO are time-dependent, intracellular PPO is de novo synthesized, the preferred substrate for extracellular PPO appears to be catechol and extracellular PPO can be partially purified by a combination of dialysis and ammonium sulfate fractionation as well as possibly DEAE chromatography and/or Sephadex G-150 gel filtration.
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    URL: http://dx.doi.org/10.1007/BF01569537
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    A quantitative method for determining the efficacy of algicides in industrial cooling towers (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 429-434 
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    ISSN: 1476-5535
    Keywords: Sampling ; Biofilm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Quantitative sampling of periphyton from natural substrates is difficult and uncommon due to the nonhomogenous and irregular nature of most natural substrates. This paper describes an experimentally verified method for quantitative sampling of periphyton directly from the relatively homogenous and regular upper deck of a cooling tower.
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    URL: http://dx.doi.org/10.1007/BF01569638
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    The effect of whey protein hydrolyzates on the lactic acid fermentation (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 71-75 
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    ISSN: 1476-5535
    Keywords: Lactobacillus bulgaricus ; Whey permeate ; Peptide average molecular weight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The batch fermentation of whey permeate to lactic acid was improved markedly by the addition of enzymehydrolyzed whey protein. Acid concentrations greater than 90 g/l were achieved at a productivity of 4.3 g/l per h and a 98% substrate use. Cell mass concentration reached 6 g/l. The acid productivity achieved is somewhat higher than that typical for fermentation of whole whey. The process economics, based on in-house hydrolyzate preparation, look promising. Presented in this paper are the experimental results showing the effects of hydrolyzate concentration on acid and cell mass production.
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    URL: http://dx.doi.org/10.1007/BF01569696
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    High-temperature, salt-tolerant xanthanase (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 127-133 
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    ISSN: 1476-5535
    Keywords: Salt-tolerant enzyme ; Heat-tolerant enzyme ; Depolymerase ; Lyase ; Oligosaccharide ; Viscosity breaker
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A new high-temperature, salt-tolerant xanthanase suitable as an enzymic viscosity breaker for xanthanbased hydraulic fracture fluids was obtained by soil enrichment growth on xanthan gum incubated at 45°C in the presence of 3% NaCl. The mixed culture produces exoenzymes functional up to 65°C in the presence of salts. Degradation products include the pyruvic acetal of mannose and branched oligosaccharides derived from cleavage of main-chain β-(1→4)-d-glucosyl linkages. Release of the terminal pyruvic acetal ofd-mannose leads to oligosaccharide products that evidently contain the ene-4,5-unsaturated glucuronic acid residue.
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    URL: http://dx.doi.org/10.1007/BF01569797
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    Comparative testing and evaluation of hard-surface disinfectants (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 145-154 
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    ISSN: 1476-5535
    Keywords: Disinfectant ; Hypochlorite ; Chlorine dioxide ; Iodine ; Hydrogen peroxide ; Glutaraldehyde ; Quaternary ammonium compound ; Phenol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The activity of eleven disinfectants againstStaphylococcus aureus, Pseudomonas aeruginosa, andSaccharomyces cerevisiae was determined using a method based on the A.O.A.C. germicidal and detergent sanitizer assay. Based on the activity against the test organisms after 30-and 60-s exposures to each disinfectant, the disinfectant containing chlorine dioxide had the highest biocidal activity in this assay, on a mg/l basis. In addition, a disinfectant containing sodium hypochlorite and a disinfectant containing sodium chlorite performed well, at concentrations below label specifications. The results illustrate the importance of testing disinfectants in the context of their intended use.
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    URL: http://dx.doi.org/10.1007/BF01569799
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    Comparative study of some microbial arabinan-degrading enzymes (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 173-180 
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    ISSN: 1476-5535
    Keywords: Arabinan-degrading enzyme ; Arabanase ; p-Nitrophenyl-α-l-arabinosidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A variety of thermophilic organisms andBacillus species were screened in shake flask culture for arabanase andp-nitrophenyl-α-l-arabinosidase activities. Highest arabanase activity was produced by strains ofThielavia terrestris andSporotrichum cellulophilum. Thermoascus aurantiacus and severalBacillus species were most active producers of arabinosidase. Arabinosidases fromBacillus strains had pH optima in the range 5.9–6.7. pH optima of fungal arabinosidases ranged from ≤2.9 to 6.7.Bacillus arabanases had neutral pH optima, whereas fungal arabanases had pH optima in the range 3.7–5.1. In general, arabinosidases were found to be relatively thermostable, retaining 〉70% activity for 3 h at 60°C. TheT. aurantiacus enzyme retained 98% activity at 70°C after 3 h.Bacillus arabanases were relatively unstable. All fungal arabanases except theT. aurantiacus enzyme were fully denatured at 70°C after 3 h.
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    URL: http://dx.doi.org/10.1007/BF01574074
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    Naturally produced isocoumarins: inhibitors of calmodulinsensitive cyclic guanosine 3′,5′-monophosphate phosphodiesterase (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 209-213 
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    ISSN: 1476-5535
    Keywords: Isocoumarin ; Phosphodiesterase ; Enzyme inhibitor ; cGMP phosphodiesterase ; Secondary metabolite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Three isocoumarins have been isolated from a strain ofStreptoverticillium sp. and all inhibit the calmodulin-sensitive cyclic guanosine 3′,5′-monophosphate phosphodiesterase (EC 3.1.4.17, Boehringer Mannheim). Two of the compounds, 6,8-dihydroxy-7-methoxy-3-methyl isocoumarin and 6,7,8-trihydroxy-3-methyl isocoumarin have previously been isolated fromStreptomyces. The third fermentation product, 6,8-dihydroxy-3-methyl isocoumarin, was also found as a metabolite ofCeratocystis minor, a fungal species associated with the blue stain disease of pine [2,3].
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    URL: http://dx.doi.org/10.1007/BF01574078
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    Microbial selective plugging and enhanced oil recovery (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 215-229 
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    ISSN: 1476-5535
    Keywords: Microbial enhanced oil recovery ; Microbial selective plugging ; Petroleum microbiology ; Permeability ; Biofouling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The ability of indigenous populations of microorganisms in Berea sandstone to improve the volumetric sweep efficiency and increase oil recovery by in situ growth and metabolism following the injection of nutrients was studied. Cores of differing permeabilities connected in parallel without crossflow and slabs of sandstone with differing permeabilities in capillary contact to allow crossflow were used. The addition of a sucrosenitrate mineral salts medium stimulated the growth and metabolism of microorganisms in the sandstone systems. This resulted in a preferential decrease in permeability in the core or slab with the higher initial permeability, diverted flow into the lower-permeability core or slab and improved the volumetric sweep efficiency. Injectivity into the slab with the lower initial permeability in the crossflow system increased during subsequent nutrient injections. Thus, microbial selective plugging does occur in laboratory systems that have the complex flow patterns observed in petroleum reservoirs without losing the ability to inject fluids into the formation. In situ microbial growth and metabolism increased oil recovery 10 to 38% of the original oil in place. Biogenic gas production accompanied oil production, and much of the gas was entrained within the produced oil suggesting that gas production was an important factor leading to increased oil recovery. Quantitation of the amount of phospholipid in the core confirmed that microbial growth preferentially occurred throughout the core with the higher initial permeability. These data showed that in situ microbial growth in the high-permeability regions improved not only the volumetric sweep efficiency but also the microscopic oil displacement efficiency.
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    URL: http://dx.doi.org/10.1007/BF01574079
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    The anaerobic biodegradation ofo-, m- andp-cresol by sulfate-reducing bacterial enrichment cultures obtained from a shallow anoxic aquifer (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 255-266 
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    ISSN: 1476-5535
    Keywords: Sulfate-reduction ; Anaerobic biodegradation ; Ground water ; Bacterial enrichment ; Phenol ; Cresol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Sulfate-reducing bacterial enrichments were obtained from a shallow anoxic aquifer for their ability to metabolize eithero-, m-, orp-cresol. GC/MS and simultaneous adaptation experiments suggested that the anaerobic decomposition ofp-cresol proceeds by the initial oxidation of the aryl methyl group to formp-hydroxybenzoic acid. This intermediate was then converted to benzoic acid. Benzoic acid and a hydroxybenzaldehyde were also found in spent culture fluids from ano-cresol-degrading enrichment culture. This result, in addition to others, suggested thato-cresol may also be anaerobically degraded by the oxidation of the methyl substituent. An alternate pathway for anaerobicm-cresol decomposition might exist. Enrichment cultures obtained with eitherp- oro-cresol degraded both of these substrates but notm-cresol. In contrast, am-cresol enrichment culture did not metabolize theortho orpara isomers. Anaerobic biodegradation in all enrichment cultures was inhibited by molybdate and oxygen, and was dependent on the presence of sulfate as a terminal electron acceptor. The stoichiometry of sulfate-reduction and substrate depletion by the various enrichment cultures indicated that the parent cresol isomers were completely mineralized. This result was confirmed by the conversion of14C-labeledp-cresol to14CO2. These results help clarify the fate of alkylated aromatic chemicals in anoxic aquifers.
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    Effects of organotin and organolead compounds on yeasts (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 279-288 
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    ISSN: 1476-5535
    Keywords: Lead ; Organotins ; Organoleads ; Tin ; Tributyltin ; Yeasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Four methods were used to screen nine organotin and two organolead compounds for toxicity to 29 yeasts, representing 10 genera. Center well diffusion plates were useful in comparing the sensitivity of yeasts to the most toxic organometals but were not useful for comparisons between compounds because of differences in diffusion rates and lack of sensitivity. Two-layer diffusion plates (density gradient plates) were also of limited use for comparisons between compounds but provided quantitative information on toxicity and allowed comparisons between organisms. Two-dimensional diffusion plates were useful for estimating the effect of pH on organometal toxicity. Release of K+ from cell suspensions measured using a K+-electrode provided quantitative information and allowed comparisons between compounds and organisms. The presence of 3% NaCl in cell suspensions decreased the rates and extent of organotin-induced K+ release. Yeasts varied in their sensitivity from strain to strain, but tributyltin was the most toxic compound tested. Mono- and dimethyltins were the least toxic. Triphenyltin, dibutyltin, monobutyltin, trimethyltin, triethyltin, diethyllead, diethyltin, and dimethylleads showed intermediate toxicity, but triphenyltin and monobutyltin were the most toxic among the group.
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    Thermal inducible expression of xylose isomerase and its performance in a hollow fiber bioreactor (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 1-5 
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    ISSN: 1476-5535
    Keywords: Xylose isomerase ; Enzyme expression ; thermally inducible ; Hollow fiber bioreactor ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary TheEscherichia coli xylose isomerase (EC 5.3.1.5) has been expressed under the control of a thermal inverting promotor system (att-nutL-p-att-N block) and its performance in a hollow fiber bioreactor measured. The conversion of xylose to xylulose was inversely proportional to the flow rate and the system operated up to 60°C. The maximum conversion efficiency observed was 19.05% at 55°C.
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    URL: http://dx.doi.org/10.1007/BF01569686
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    Liquid holding recovery and photoreactivation of UV-induced damage inStreptococcus lactis (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 13-17 
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    ISSN: 1476-5535
    Keywords: Streptococcus lactis ; UV irradiation ; Liquid holding recovery ; Photoreactivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Repair of ultraviolet-light-induced DNA damage inStreptococcus lactis has been examined. The wild-type strain and its derivative Lac− possess a dark repair system (maximal increase in survival of 4-fold). Enzymatic photoreactivation exists in the two strains but a weaker photoreactivability was found in the Lac− derivative (4 and 2-fold, respectively). Concomitant reduction of UV-induced mutagenesis (Rifr marker) was also studied during these two repair phenomena. The absence of dark repair after saturation of photoreactivation suggests that photoreactivation is much more efficient with pyrimidine dimers as substrate.
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    URL: http://dx.doi.org/10.1007/BF01569688
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    Secretion of the sweet-tasting plant protein thaumatin byStreptomyces lividans (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 37-42 
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    ISSN: 1476-5535
    Keywords: Exported recombinant protein ; Recombinant protein ; β-Galactosidase ; Leader peptide ; Thaumatin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary To produce and direct the export inStreptomyces lividans of the sweet plant protein thaumatin, thaumatin II cDNA was fused in the correct reading frame to the β-galactosidase leader peptide, under the control of the β-galactosidase promoter and ribosome binding site. The export of the recombinant thaumatin may allow the correct formation of the thaumatin disulfide bonds. The recombinant thaumatin was purified from the medium on an S-Sepharose column and detected with western blots by sheep α-thaumatin antibodies. The recombinant thaumatin was the same size as authentic thaumatin and changed position on an acrylamide gel in response to reduction by 2-mercaptoethanol in the same manner.
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    URL: http://dx.doi.org/10.1007/BF01569691
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    Improved strains for production of xanthan gum by fermentation ofXanthomonas campestris (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 55-64 
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    ISSN: 1476-5535
    Keywords: Rifampicin ; Bacitracin ; Exopolysaccharide ; Productivity ; Viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Two classes of mutants ofXanthomonas campestris B1459 were isolated that accumulate more xanthan gum than the parental wild-type in culture broths of shake flask cultures and both batch and fed-batch fermentations. The first mutant class was resistant to the antibiotic rifampicin and accumulated, on average, about 20% more xanthan gum than wild-type. The second mutant class, a derivative of the first, was resistant to both bacitracin and rifampicin, and accumulated about 10% more xanthan than its parent. On a weight basis, the viscosities of the polysaccharides made by each strain were not distinguishable. Only a subset of the drug-resistant mutants were overproducers of xanthan. The biochemical basis for the overproduction of xanthan by the mutant strains has not been determined. Both new strains served as recipients for recombinant plasmids bearing ‘xanthan’ genes and further augmented the effects of multiple copies of those genes on xanthan productivity.
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    The effect of whey protein hydrolyzate average molecular weight on the lactic acid fermentation (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 77-80 
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    ISSN: 1476-5535
    Keywords: Lactobacillus bulgaricus ; Endoprotease ; Peptide average molecular weight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The batch fermentation of whey permeate to lactic acid was improved by supplementing the broth with enzyme-hydrolyzed whey protein. Hydrolyzates prepared with endoprotease were more stimulatory to acid production rates than were those prepared with exo/endo protease. The effect of hydrolyzate average molecular weight on acid production is presented. Results show that the hydrolyzate having an average molecular weight of 700 is the most stimulatory to acid production rates.
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    Influence of acetic and butyric acid addition on polysaccharide formation byClostridium acetobutylicum (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 121-125 
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    ISSN: 1476-5535
    Keywords: Clostridium acetobutylicum ; Granulose ; Capsule ; Exopolysaccharide ; Oxido-reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The production of granulose (an intracellular reserve polygranule), capsule and exopolysaccharide was investigated in a synthetic medium in which the oxido-reduction level was modified by the addition of acetic or butyric acid. After addition of the acids, granulose synthesis increased from 150 to 300 mg glucose equivalents ·1−1 and capsular synthesis decreased by 25%. Exopolysaccharide production was unchanged under these conditions. A hypothesis that attributes a role to the polymer in the oxido-reduction sequences is discussed.
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    Mutants ofXanthomonas campestris defective in secretion of extracellular enzymes (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 135-144 
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    ISSN: 1476-5535
    Keywords: Xanthomonas campestris ; Xanthan gum ; Secretion ; Cellulase ; Amylase ; Pathogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Mutants ofXanthomonas campestris B 1459 were isolated that are defective in secretion of both cellulase and amylase. Both enzymes accumulated in the periplasmic space. The defects in secretion of cellulase or amylase were partly overcome by introducing into the mutants specific multiple copies of DNA cloned fromX. campestris, and presumed to code for cellulase or amylase enzymes. The mutant strains also showed reduced amounts of extracellular pectinase and protease activities, as if the mutants were generally defective for secretion of extracellular enzymes. The mutants showed reduced pathogenesis for turnip seedlings. The secretion-defective mutants may allow production of xanthan gum with reduced cellulose, pectin, protein and starch-degrading enzyme activities, thereby allowing more widespread mixing of microbially produced xanthan gum with these commercially important water-soluble polymers.
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    Growth ofRhizopus arrhizus in fermentation media (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 155-161 
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    ISSN: 1476-5535
    Keywords: Rhizopus arrhizus ; Fungal growth ; Filamentous growth ; Hyphal morphology ; Fermentation medium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Rhizopus arrhizus biomass attached itself to fermentor walls, baffles and impellers when grown in casein/ glucose media. In shake flasks, dispersed filamentous growth was produced in media containing certain concentrations of glucose and soya flour. Other media tested produced pelleted or clumpy growth. Medium initial pH did not affect morphology type. Dispersed growth could not be obtained by addition of detergents, oils and polymers to a clear glucose/soya peptone medium. Addition of maize solids to this medium resulted in dispersed growth which occurred even in the presence of calcium, which in most media caused pellet formation. Mycelia appeared to bind to the maize particles and use these as growth centres thereby preventing pellet or clump formation. Mycelial pellets appeared to originate either from a single spore or by interaction of branched hyphae from different spores. Medium composition and macro-morphology type correlate with differences in hyphal structures.
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    Comparison of lethalities in mouse versus goldfish for clinical and food isolates ofAeromonas hydrophila (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 189-193 
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    ISSN: 1476-5535
    Keywords: Gastroenteritis ; Cytotoxin ; Food safety
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The lethality of 16 clinical or food isolates ofAeromonas hydrophila was assessed by determination of LD50 (i.p.) in mice and goldfish. In mice LD50 values for the variousA. hydrophila strains were similar, ranging from 1.2–21.0×108 cells/animal. A wider range of LD50 values, 0.03–11.8×108 cells/animal, was observed with goldfish. Lethality was not correlated between the two test animals. Further, cytotoxic response in Y-1 adrenal cells did not correlate with lethality in either test animal. It appears that lethality is not a good measure of potential enterotoxigenicity, but may be useful in assessing the invasive character of isolates causing systemic infections in immunocompromised hosts.
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    Further studies on the biosynthesis of the avermectins (1989)
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    Journal of industrial microbiology and biotechnology 4 (1989), S. 231-237 
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    ISSN: 1476-5535
    Keywords: Avermectin ; Streptomyces avermitilis ; Biosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The biosynthesis of avermectins was studied further inStreptomyces avermitilis MA5502 by feeding experiments with labeled precursors.13C-NMR analysis of the compounds biosynthesized from [2-13C]acetate, [1,2-13C2]acetate, [3-13C]propionate and [2,3-13C2]propionate confirmed that the aglycone of avermectins is made from seven intact acetate and five propionate units. Feeding experiments with [1-13C]2-methylbutyrate and [1-13C]isobutyrate have shown that 2-methylbutyrate and isobutyrate are immediate precursors of the starter units of the polyketide chains of avermectin ‘a’ and ‘b’ components, respectively. The3H/14C doublelabeling experiments suggest that the two oleandrose moieties are derived from glucose.
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    Effect of photoreactivating light on survival of ultraviolet-light-irradiatedStreptomyces lividans 66 (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 7-12 
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    ISSN: 1476-5535
    Keywords: Photoreactivation ; Streptomyces lividans ; UV survival ; Visible light
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Biological systems can repair damage induced in their DNA by ultraviolet light (UV). Most cells contain at least three DNA repair pathways, each of which has a marked effect on UV survival. Excision repair and recombinational (postreplication) repair are light-independent whereas photoreactivation (PR), whether enzyzmatic or photochemical, is light-dependent. The specificity of photoreactivation for UV-induced DNA damage allows it to be used as a tool for examining whether premutational DNA lesions are preferred sites for photoreversal; it therefore plays an important role in mutagenesis studies. Evidence is presented here that PR occurs in a time-dependent fashion in three strains ofStreptomyces lividans 66. The effect appears to be independent of temperature and is observed only when PR treatment is given after UV irradiation. The present experiments do not discriminate between enzymatic and photochemical protection.
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  • 97
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    Electronic Resource
    Metabolism of chlorinated methanes, ethanes, and ethylenes by a mixed bacterial culture growing on methane (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 29-35 
    Details
    ISSN: 1476-5535
    Keywords: Methane-utilizing bacteria ; Halogenated hydrocarbons ; Trichloroethylene ; Chloroform ; Dichloromethane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Soil was taken from the top 10 cm of a soil column that removed halogenated aliphatic hydrocarbons in the presence of natural gas. This soil was used as an enrichment inoculum to determine that the removals seen in the soil column were in fact of a microbiological nature. Methane served as the source of carbon and energy and was consumed immediately by the enrichments. After several transfers of the enrichments, a stable consortium of at least three bacterial types was obtained. The predominant bacterium was a non-motile, gram-negative coccus. This stable consortium was able to remove chlorinated methanes, ethanes, and ethylenes when grown with methane and oxygen in the headspace. Methane was required for the removals to be observed. Acetylene inhibited the removals, which further suggests the involvement of methanotrophs. Benzene and toluene were removed by the mixed culture with or without methane in the headspace. Fatty acid analysis of the mixed culture resulted in a profile that indicated that the predominant organism was a type II methanotroph. This study provides further evidence that methanotrophic bacteria are capable of cometabolizing a wide range of chlorinated methanes, ethanes, and ethylenes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569690
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  • 98
    Electronic Resource
    Electronic Resource
    Biotransformation of aromatic aldehydes bySaccharomyces cerevisiae: Investigation of reaction rates (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 49-53 
    Details
    ISSN: 1476-5535
    Keywords: l-Phenylacetyl carbinol ; Saccharomyces cerevisiae ; Yeast ; Benzaldehyde ; Biotransformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The rate of production ofl-phenylacetyl carbinol bySaccharomyces cerevisiae in reaction mixtures containing benzaldehyde with sucrose or pyruvate as cosubstrate was investigated in short 1 h incubations. The effect of yeast dose rate, sucrose and benzaldehyde concentration and pH on the rate of reaction was determined. Maximum biotransformation rates were obtained with concentrations of benzaldehyde, sucrose and yeast of 6 g, 40 g and 60 g/l, respectively. Negligible biotransformation rates were observed at a concentration of 8 g/l benzaldehyde. The reaction had a pH optimum of 4.0–4.5. Rates of bioconversion of benzaldehyde and selected substituted aromatic aldehydes using both sucrose and sodium pyruvate as cosubstrate were compared. The rate of aromatic alcohol production was much higher when sucrose was used rather than pyruvate.o-Tolualdehyde and 1-chlorobenzaldehyde were poor substrates for aromatic carbinol formation although the latter produced significant aromatic alcohol in sucrose-containing media. Yields of 2.74 and 3.80 g/l phenylacetyl carbinol were produced from sucrose and pyruvate, respectively, in a 1 h reaction period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569693
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  • 99
    Electronic Resource
    Electronic Resource
    High solids fermentation of hydrolysates of wheat starch B in a continuous dynamic immobilized biocatalyst bioreactor (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 81-84 
    Details
    ISSN: 1476-5535
    Keywords: Ethanol fermentation ; Wheat starch ; Saccharomyces cerevisiae ; immobilization ; Continuous dynamic immobilized biocatalyst bioreactor ; Biocatalyst bioreactor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A simple and efficient method of conversion of wheat starch B to ethanol was investigated. Employing a two-stage enzymatic saccharification process, 95% of the wheat starch was converted to fermentable sugars in 40 h. From 140 g/l total sugars in the feed solution, 63.6 g/l ethanol was produced continuously with a residence time of 3.3 h in a continuous dynamic immobilized biocatalyst bioreactor by immobilized cells ofSaccharomyces cerevisiae. The advantages and the application of this bioreactor to continuous alcoholic fermentation of industrial substrates are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569698
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  • 100
    Electronic Resource
    Electronic Resource
    History of yield improvements in the production of asperlicin byAspergillus alliaceus (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 97-104 
    Details
    ISSN: 1476-5535
    Keywords: Fermentation development ; Cholecystokinin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The natural product asperlicin is the first nonpeptide antagonist of cholecystokinin isolated from a microbial source. At discovery, production of asperlicin by the original soil isolate ofAspergillus alliaceus was between 15 and 30 mg/l. Selection of natural variants ofA. alliaceus, use of Plackett & Burman and Simplex experimental designs; formulation of synthetic media; amino acid supplementation of production media; analysis of complex nitrogen sources for their amino acid content; evaluation of promising media in fermentors; substitution of glycerol for glucose as a carbon source and rational mutant selection all contributed to titer increases to 〉900 mg/l.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569793
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