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  • Articles  (48,776)
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  • Articles  (48,776)
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  • 1985-1989  (43,336)
  • 1950-1954
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  • 1
    Electronic Resource
    Electronic Resource
    A mathematical derivation of the P-V relation at end-systole (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 35-41 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A dynamical model of the left ventricle as a thick-walled cylinder contracting radially is used to derive the P-V (pressure-volume) relation in the left ventricular cavity during contraction. It is shown how the mathematical results derived could apply to experimental results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02459976
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  • 2
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    Stability of discrete one-dimensional population models (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 67-75 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We give conditions for local and global stability of discrete one-dimensional population models. We give a new test for local stability when the derivative is −1. We give several sufficient conditions for global stability. We use these conditions to show that local and global stability coincide for the usual models from the literature and even for slightly more complicated models. We give population models, which are in some sense the simplest models, for which local and global stability do not coincide.
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    URL: http://dx.doi.org/10.1007/BF02459978
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  • 3
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    Sequence comparison with concave weighting functions (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 97-120 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We consider efficient methods for computing a difference metric between two sequences of symbols, where the cost of an operation to insert or delete a block of symbols is a concave function of the block's length. Alternatively, sequences can be optimally aligned when gap penalties are a concave function of the gap length. Two algorithms based on the ‘candidate list paradigm’ first used by Waterman (1984) are presented. The first computes significantly more parsimonious candidate lists than Waterman's method. The second method refines the first to the point of guaranteeingO(N 2 lgN) worst-case time complexity, and under certain conditionsO(N 2). Experimental data show how various properties of the comparison problem affect the methods' relative performance. A number of extensions are discussed, among them a technique for constructing optimal alignments inO(N) space in expectation. This variation gives a practical method for comparing long amino sequences on a small computer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02459948
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  • 4
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    On the incompatibility of gompertz or weibull survival dynamics with exponentially distributed individual lifespans (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 187-192 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract It is well documented, in the biological literature, that many species throughout the animal kingdom exhibit Gompertzian or Weibull-like population level total survival distributions. Many researchers have long assumed, believed, or otherwise postulated that an individual organism, in such a population, survived according to an exponential survival distribution. Using well-known results from reliability theory, it is shown that if every individual in the population has an exponentially distributed lifespan, then a Gompertzian or Weibull-like group/population level dynamics (or any other dynamics with a strictly increasing mortality rate for some interval) is not possible. This implies that, for species with a population level Gompertzian or Weibull (with the mortality rate strictly increasing) survival curve, some or all of the individual organisms must have non-exponentially distributed lifespans.
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    URL: http://dx.doi.org/10.1007/BF02459951
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  • 5
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    Identifiability of DNA distribution from flow cytometric data with cell debris (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 209-225 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract In flow cytometric measurement of cell DNA distribution one of the major problems is accounting for the effect of fragmentation in the staining process. This work considers a recent probabilistic model that has been proposed for the fragmentation process and species under which conditions it is possible to uniquely identify the DNA distributions of the original population using flow cytometric data. Attention is given both to the normal and to the polyploid case.
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    URL: http://dx.doi.org/10.1007/BF02458881
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  • 6
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    Metastability in a temperature-dependent model system for predator-prey mite outbreak interactions on fruit trees (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 379-409 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The nonlinear behavior of a particular Kolmogorov-type exploitation differential equation system assembled by May (1973,Stability and Complexity in Model Ecosystems, Princeton University Press) from predator and prey components developed by Leslie (1948,Biometrica 35, 213–245) and Holling (1973,Mem. Entomol. Soc. Can. 45, 1–60), respectively, is re-examined by means of the numerical bifurcation code AUTO 86 with model parameters chosen appropriately for a temperature dependent mite interaction on fruit trees. The most significant result of this analysis is that, in addition to the temperature ranges over which the single community equilibrium point of the system iseither globally stableor gives rise to a globally stable limit cycle, there can also exist a range wherein multiple stable states occur. These stable states consist of a focus (spiral point) and a limit cycle, separated from each other in the phase plane by an unstable limit cycle. The ecological implications of such metastability, hysteresis and threshold behavior for the occurrence of outbreaks, the persistence of oscillations, the resiliency of the system and the biological control of mite populations are discussed. It is further suggested that a model of this sort which possesses a single community equilibrium point may be more useful for representing outbreak phenomena, especially in the presence of oscillations, than the non-Kolmogorov predator-prey systems possessing three community equilibrium points, two of which are stable and the other a saddle point, traditionally employed for this purpose.
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    URL: http://dx.doi.org/10.1007/BF02459707
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  • 7
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    A simple mathematical model of the thermal death of microorganisms (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 493-501 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract This note is concerned with a simple mathematical model of how a population of bacterial spores decrease with time when subjected to a uniform temperature. The model assumes that there is a Boltzman distribution of energy among water or other molecules surrounding the assumed single lethal target in a spore; it assumes that repair is not possible; and that only molecules with energies above a critical level cause inactivation. The model provides new insight concerning the ‘kill-rate’ of spores during ultra heat treatment.
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    URL: http://dx.doi.org/10.1007/BF02458848
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  • 8
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    1988 Gordon Conference on Theoretical Biology and Biomathematics (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 95-95 
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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/BF02459981
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  • 9
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    Computational simulation of activity of cortical-like neural systems (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 143-185 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The kinetic theory of neural systems is extended to include the description of cortical-like neural structures. This fact is accomplished by the introduction of long-distance effects. Collaterally, we have the separation of the description of the excitatory activity from that of the inhibitory one. Also, the description of neural systems with a high level of activity is obtained. The modified theory is used to simulate computationally the activity of cortical-like neural systems.
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    URL: http://dx.doi.org/10.1007/BF02459950
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  • 10
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    Simulation of cellular compaction and internalization in mammalian embryo development—II. Models for spherical embryos (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 121-142 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A model based upon minimization of surface energy as an explanation for the phenomena of compaction and internalization of cells during mammalian embryo development is generalized for three-dimensional cells. It is shown that, for a spherical embryo, if cells are assumed to be polygonal cones in shape, the simulation of these phenomena for three-dimensional cells is equivalent to simulations of deformations of two-dimensional cells on the surface of a sphere. This equivalence is used to show that in the optimal compacted structure, with no internal cells, the cross-sections of cells in general are not regular polyhedra. Further, the internalization occurs when the number of cells exceeds a critical value which seems to depend on the relative sizes and biophysical properties of cells.
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    URL: http://dx.doi.org/10.1007/BF02459949
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  • 11
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    Interactions leading to persistence in predator-prey systems with group defence (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 517-530 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract In previous work (Freedman and Wolkowicz, 1986;Bull. math. Biol. 48, 493–508) it was shown that in a predator-prey system where the prey population exhibits group defence, it is possible that enrichment of the environment could lead to extinction of the predator population. In this paper a third population is introduced and criteria are derived under which persistence of all populations will occur. In particular, criteria for a superpredator and for a competitor to stabilize the system in the sense of persistence are analyzed.
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  • 12
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    The unstirred layer during osmotic flow into a tubule (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 531-545 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The interaction between osmotic inflow through the wall of a narrow tubule and bulk flow in the tubule is described. Solution are found by a finite difference method, and two approximate analytic solutions are given. Results given here enable more accurate estimates of osmotic permeability to be obtained for the tubule wall. The theory predicts the behaviour of unstirred layers as experimental parameters are varied and enables tubule experiments to be designed so as to reduce unwanted unstirred layer effects.
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    URL: http://dx.doi.org/10.1007/BF02458851
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  • 13
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    Book reviews (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 567-576 
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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/BF02458854
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  • 14
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    Software survey section (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), 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/BF02458856
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  • 15
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    Stationary mutant distributions and evolutionary optimization (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 635-660 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Molecular evolution is modelled by erroneous replication of binary sequences. We show how the selection of two species of equal or almost equal selective value is influenced by its nearest neighbours in sequence space. In the case of perfect neutrality and sufficiently small error rates we find that the Hamming distance between the species determines selection. As the error rate increases the fitness parameters of neighbouring species become more and more important. In the case of almost neutral sequences we observe a critical replication accuracy at which a drastic change in the “quasispecies”, in the stationary mutant distribution occurs. Thus, in frequently mutating populations fitness turns out to be an ensemble property rather than an attribute of the individual. In addition we investigate the time dependence of the mean excess production as a function of initial conditions. Although it is optimized under most conditions, cases can be found which are characterized by decrease or non-monotonous change in mean excess productions.
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    URL: http://dx.doi.org/10.1007/BF02460094
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  • 16
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    Time-dependent subpopulation induction in heterogeneous tumors (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 681-696 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Time-dependent induction of clonal heterogeneity in the neoplastic micro-environment is analysed within the context of a competitive ecology. A model that describes a constant source for clonal emergence was analysed by Michelsonet al. (1987) as an extension of a model proposed by Jansson and Revesz (1974). The extended model has been termed the JRE Model. This paper extends these analyses to time-dependent emergence rates which may represent induction in the presence of a cytotoxic agent. If the analysis is constrained to the tumor micro-environment, and if the emergent subpopulation is drug resistant, then the model may describe the induction and emergence of drug resistant subclones in a growing neoplasm. Asymptotic closed form solutions are derived for a class of emergence rate functions which decay asymptotically to a constant mutation rate. This underlying mutation rate may represent spontaneous mutation to the resistant phenotype, and has been analysed stochastically (Coldmanet al., 1985). The asymptotic solutions to the time-dependent model approach the steady state solution for the JRE Model which represents the dynamics observed in the presence of a constant, spontaneous mutation rate. The clinical and biological implications of these results are discussed.
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    URL: http://dx.doi.org/10.1007/BF02460096
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  • 17
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    Book reviews (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 697-700 
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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/BF02460097
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  • 18
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    The Society for Mathematical Biology is pleased to announce an Annual Best Paper Award of $1000 (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 701-701 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
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    URL: http://dx.doi.org/10.1007/BF02460098
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  • 19
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    Editorial: Software survey section (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. I 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
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    URL: http://dx.doi.org/10.1007/BF02460099
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  • 20
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    HIV spread in the San Francisco cohort: Scaling of the effective logistic rate for seropositivity (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 345-349 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A simple scaling (semigroup) property is manifest in the functional form of the effective logistic rate for the increase in the HIV seropositive fraction in the San Francisco (City Clinic) cohort. Witht i=4.5 years, this scaling property—r→λ-2r undert→[λt+(λ−1)t i] for all parameter values λ≧1—encapsulates the effects of relevant biological and sociological changes in the key epidemiological variables during the 8-year seropositive rise period, 1978–1985 inclusive.
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    URL: http://dx.doi.org/10.1007/BF02459704
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  • 21
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    Subcellular distribution of compounds in biosystems (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 367-378 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Using plausible assumptions a description of the distribution of externally added low molecular weight solutes in individual subcellular regions of biosystems is reduced to a compartmental system of specific structure having, in general, only numerical solutions. Frequently occurring application of biologically active substances in low doses, however, elicits the conditions (i.e. undirectional membrane transport involving accumulation, instantaneous and linear binding to macromolecules and metabolism obeying first order kinetics) that enable one to solve the system explicitly. Equations have been derived, describing the time course of drug concentration in any subcellular phase of arbitrary biosystem having membranes of similar composition, including tissues with a cellular structure (degenerate case). Accuracy of the description is tested on the relationship between physicochemical and biological properties of drugs, bioactivity being used to monitor the concentration in the receptor region.
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    URL: http://dx.doi.org/10.1007/BF02459706
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  • 22
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    Book reviews (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 411-419 
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    ISSN: 1522-9602
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    Topics: Biology , Mathematics
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    URL: http://dx.doi.org/10.1007/BF02459708
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  • 23
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    The osmotic permeability of a tubule wall (1988)
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    Bulletin of mathematical biology 50 (1988), S. 547-558 
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    ISSN: 1522-9602
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    Topics: Biology , Mathematics
    Notes: Abstract The influence of unstirred layers in osmotic experiments designed to measure the osmotic permeability of a tubule wall is considered. Results are given in the form of a set of graphs whose axes are closely related to observed and known experimental parameters. These enable osmotic permeability values to be obtained which are closer to the true values.
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  • 24
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    The fractal dimension of EEG as a physical measure of conscious human brain activities (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 559-565 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract In our previous paper we have given a neuroglia modulated neuronal network model which may display chaotic behaviours under certain parametric values. This work is an attempt to correlate the functions of conscious human brains with the chaotic states shown by the EEG patterns under different physiological conditions. Some of the difficulties and precautions of this kind of work are discussed.
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  • 25
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    Critical issues in tumor microcirculation, angiogenesis and metastasis (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 577-577 
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  • 26
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    On the validity of the steady state assumption of enzyme kinetics (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 579-593 
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    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract By estimating relevant time scales, a simple new condition can be found that ensures the validity of the steady state assumption for a standard enzyme-substrate reaction. The generality of the approach is demonstrated by applying it to the determination of validity criteria for the steady state assumption applied to an enzyme-substrate-inhibitor system.
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  • 27
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    Theoretical effects of radioligand diffusional gradients and microscopic neuroreceptor distribution inin vivo kinetic studies (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 423-444 
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    Notes: Abstract A simplified one-dimensional model system was used to test the possibility that physically realistic parameters would lead to the prediction of microscopic heterogeneity of radioligand distribution in the brain and that microscopic heterogeneity of radioligand and neuroreceptor distribution could influence the macroscopically observedin vivo kinetics. The model was represented mathematically by a partial differential equation which is similar to the heat diffusion equation, but with special boundary conditions. The equation was solved analytically under the condition of negligible receptor occupancy by inversion of the Laplace transform and in the more general case of arbitrary receptor occupancy by cubic spline approximation. In simulations with physically reasonable values for rate constants and parameters, we find that significant radioligand gradients can occur. Thus, the level of radioligand in the immediate vicinity of the receptor may be substantially different from the average level in a macroscopically measured region of interest. In order to analyze the simulated data, we derived a rigorous steady-state solution, including both a statement of necessary and sufficient conditions for the validity of the steady-state approximation as well as a demonstration of the proper technique for assessing the consistency of the derived parameter with the requirements of the approximation. The radioligand heterogeneity leads to significant errors in the parameters estimated in the steady-state kinetic analysis. In particular, the pseudo first-order rate constant for radioligand-neuroreceptor association, which is often used as a measure of the total amount of neuroreceptor, is underestimated. The first-order rate constant for radioligand-neuroreceptor dissociation is also underestimated. These effects can partially account for the experimentally-observed discrepancy betweenin vivo andin vitro estimates of these kinetic parameters.
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  • 28
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    An extremal criterion for epimorphic regeneration (1988)
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    Bulletin of mathematical biology 50 (1988), S. 595-634 
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    ISSN: 1522-9602
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    Topics: Biology , Mathematics
    Notes: Abstract Many developing systems obey the principle of continuity: a morphogenetic field, when perturbed, tends to restore the normal local pattern of structures in its organ district. We have investigated physical field theories for a morphogenetic field, seeking constraints which would make a field theory produce the principle of continuity. We assume that during embryonic (ontogenetic) development a leg develops a pattern of positional values and a length which extremize a time-independent functional—the integral, over the length of the leg, of a function of positional values and position. For a single state variable which represents positional value, if a unique extremizing solution for the ontogenetically generated pattern and the length exists, and if no position-dependent functions other than the state variable appear in the integrand, then the principle of continuity is valid: in any regenerated leg the state variable is continuous and each region is locally identical to a region of the ontogenetically generated leg. This proposition is applied to three simple examples. For an exponential gradient and a Jacobi elliptic function there is a set of parameter values and boundary values for which a functional is minimized and the ontogenetically generated leg has an optimal length. Thus a leg which meets these constraints will obey the principle of continuity. However, a functional which when extremized gives a sinusoidal pattern does not in general provide a unique extremal length. Mathematical conditions are discussed under which an ontogenetically generated limb or a regenerated limb represents an asymptotically stable steady state. For a specific model of the transient dynamics in the exponential gradient case, the steady state gradient is asymptotically stable.
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  • 29
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    Rhythmic signalling and entrainment inVespa orientalis larvae: Characterization of the underlying interactions (1988)
    Springer
    Bulletin of mathematical biology 50 (1988), S. 661-679 
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    Notes: Abstract Rhythmic “circa-second” contrations of larvae of the hornetVespa orientalis, believed to serve as hunger signals, were studied. A considerable degree of coordination among individual larvae, both in frequency and phase of these contractions, has been observed. The oscillations of singly isolated larvae are of short duration, non-constant, with increasing intervals in between and there is a substantial variability in the patterns shown by different larvae. In contrast, the association of two or more larvae leads to enhancement of their periodic behaviour and to (partial) entrainment. Communication among larvae may perhaps be mediated by the sound pulses (“scratching” noises) which are generated by these contractions. We have subjected individual and grouped larvae to external sound pulses and were able to demonstrate: (a) enhancement of rhythmic activity; (b) phase resetting; (c) entrainment to an external oscillator within a range of frequencies; (d) the existence of a subharmonic mode of entrainment. We propose a simple phenomenologic model to account for these larvae responses. Our model assumes the existence of an “energy” variable which declines with time but is upgraded, in a phase-dependent way, by external stimuli.
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    Editorial (1988)
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    Bulletin of mathematical biology 50 (1988), S. i 
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    Multiple solutions of a model describing cancerous growth (1988)
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    Bulletin of mathematical biology 50 (1988), S. 1-17 
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    Notes: Abstract Multiple solutions of a model describing immune surveillance against cancer are studied. The model was proposed by R. Lefever and co-workers. A limit cycle solution and two kinds of wave front solutions are worked out by means of a perturbation method. The problem of nucleation concerning this model is studied by a singular-perturbation technique. In addition, the pulse wave solution is also found by numerical simulations.
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    Holography reveals the soft anatomy of ancient cephalopods (1988)
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    Bulletin of mathematical biology 50 (1988), S. 19-34 
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    Notes: Abstract It is productive to view the suture-lines on fossil cephalopod shells as simple Fraunhoeffer diffraction patterns which can be inverted, by elementary Fourier Transformation, to provide a clear holographic image of the soft body-mass that produced them. As fleshy body organs are rarely ever preserved in ancient fossils it is particularly valuable to be able to deduce soft anatomy from conspicuous and usually well-preserved shell markings. Preliminary studies reported in this paper supply insight into the ontogeny and phylogeny of ancient cephalopods.
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    RF-cell: A model for populations of randomly interconnected neurons (1988)
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    Bulletin of mathematical biology 50 (1988), S. 43-66 
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    Notes: Abstract This paper is concerned with a population of neurons with dense random interconnections, in which the stimulations between neurons are independent of their distance apart. This study is conducted from the viewpoint of the General System Theory. Proposed and used for the first time in studies on the above subject is a new concept referred to as the ‘historical report’ of the mentioned population. It will be shown that the population exhibits cyclic modes of behaviour which are dependent on its structure and historical report and which in the phase space correspond to cycles of hysteresis. A simple model in discrete time is developed and demonstrates, by the help of a computer study, the existence of the cycles of hysteresis.
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    Significance levels for biological sequence comparison using non-linear similarity functions (1988)
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    Bulletin of mathematical biology 50 (1988), S. 77-92 
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    Notes: Abstract A class of non-linear similarity functionss 1 has been proposed for comparing subalignments of biological sequences. The distribution of maximals 1-similarities is well approximated by the extreme value distribution. The significance levels ofs 1 are studied for a variety of nucleotide frequency distributions as well as for several matrices of amino acid substitution costs. Also, the significance levels ofs 1 are explored for comparing three biological sequences. Several previously described subalignments of bovine proenkephalin and porcine prodynorphin are shown to be highly significant.
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    Software survey section (1988)
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    Book reviews (1988)
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    Bulletin of mathematical biology 50 (1988), S. 193-207 
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    Mathematical studies of capillary-tissue exchange (1988)
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    Bulletin of mathematical biology 50 (1988), S. 289-311 
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    Notes: Abstract A mathematical model of capillary-tissue exchange is presented and the method of solution of the resulting equations is described. The model includes the mutual interaction of fluid movement across the capillary wall and the convection and diffusion of a number of solutes. A variety of solutions for situations of physiological interest are obtained and discussed.
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    Periodic band pattern as a dissipative structure in ion transport systems with cylindrical shape (1988)
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    Bulletin of mathematical biology 50 (1988), S. 255-288 
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    Notes: Abstract A theory is presented for appearance of periodic band patterns of ion concentration and electric potential associated with electric current surrounding a unicellular or multicellular system of a cylindrical shape. A flux continuity at the membrane (or the surface) is reduced to a nonlinear equation expressing passive and active fluxes across the membrane and intracellular diffusion flux. It is shown that, when an external parameter is varied from the sub-critical region, i.e. the homogeneous flux state, a symmetry breaking along a longitudinal axis usually appears prior to the one along a circumferential direction. The spectrum analysis shows that the correlation length is longer in the longitudinal direction. Growth of the band pattern from a patch-shaped pattern is demonstrated by the use of numerical calculations of proton concentration on the two-dimensional space of cylindrical surface. An experimental example of formative process of H+ banding is given for the internodal cell ofChara. It is shown that small patches on the surface decline or are sometimes gathered to the band surrounding the circle. The resulting pattern is suggested as a kind of dissipative structure appearing far from equilibrium.
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    Parameter-dependent transitions and the optimal control of dynamical diseases (1988)
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    Bulletin of mathematical biology 50 (1988), S. 227-253 
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    Notes: Abstract Many theoretical studies in biological and physical sciences consider the dynamical behavior of ann-dimensional ordinary differential equation that contains a large number of independent parameters. A frequently asked question is, are there permissible parameter sets that result in periodic or chaotic behavior? The large number of distinct parameters often limits the feasibility of trial and error calculations. The large dimension and nonlinearity of the system make application of analytic methods at best difficult and at worst effectively impossible. It is shown here that a computational search for parameter-dependent transitions of attractor topology can be effected by constrained optimization of quantitative measures of dynamical behavior (Hurwitz polynomials, Floquet coefficients, Lyapunov exponents and correlation dimension). As an example, we examine a three-dimensional nonlinear ordinary differential equation containing seven parameters that was constructed by Goldbeter and Segel to model periodic synthesis of cyclic AMP inDictyostelium. A search for bifurcations to periodic solutions is made by minimizing Hurwitz coefficients subject to parameter constraints. By comparing four optimization algorithms, the defects and advantages of the procedure are identified. It is also argued that it may be possible to use this characterization of dynamics to construct optimal responses to dynamical diseases (those disorders that result from parameter-dependent bifurcations in physiological control systems).
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    Persistence in discrete age-structured population models (1988)
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    Bulletin of mathematical biology 50 (1988), S. 351-366 
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    Notes: Abstract Survival analyses of populations are developed in dicrete growth processes. Persistence and extinction attributes of age-structured discrete population models are explored on both a finite and infinite time horizon. Conditions for persistence and extinction are found. Decompositions of the initial population size axes into intervals where populations are persistent at timeN and intervals leading to extinction at timen, wheren≤N, are given for two age class discrete population models.
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    A couple stress model of blood flow in the microcirculation (1988)
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    Bulletin of mathematical biology 50 (1988), S. 329-344 
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    Notes: Abstract A simple mathematical model depicting blood flow in the capillary is developed with an emphasis on the permeability property of the blood vessel based on Starling's hypothesis. In this study the effect of inertia has been neglected in comparison with the viscosity on the basis of the smallness of the Reynolds number of the flow in the capillary. The capillary blood vessel is approximated by a circular cylindrical tube with a permeable wall. The blood is represented by a couple stress fluid. With such an ideal model the velocity and pressure fields are determined. It is shown that an increase in the couple stress parameter increases the resistance to the flow and thereby decreases the volume rate flow. A comparison of the results with those of the Newtonian case has also been made.
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    Announcements (1988)
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    Bulletin of mathematical biology 50 (1988), S. 421-422 
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    Bulletin of mathematical biology 50 (1988), S. I 
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    Biological adaptation and the mathematical theory of information (1988)
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    Bulletin of mathematical biology 50 (1988), S. 445-464 
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    Notes: Abstract Adaptation is viewed as a tendency maximizing the Shannon entropy of an ecosystem, where the ecosystem is considered as two interacting subsystems, namely, the biota and its environment. We derive theadapted structures starting from three fundamental hypotheses and we apply this result to an ecological topic: the cryptic and aposematic behaviour.
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    Explosive route to chaos through a fractal torus in a generalized Lotka-Volterra model (1988)
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    Bulletin of mathematical biology 50 (1988), S. 465-491 
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    Notes: Abstract The behavior of a model that generalizes the Lotka-Volterra problem into three dimensions is presented. The results show the analytic derivation of stability diagrams that describe the system's qualitative features. In particular, we show that for a certain value of the bifurcation parameter the system instantly jumps out of a steady state solution into a chaotic solution that portrays a fractal torus in the three-dimensional phase space. This scenario, is referred to as the explosive route to chaos and is attributed to the non-transversal saddle connection type bifurcation. The stability diagrams also present a region in which the Hopf type bifurcation leads to periodic and chaotic solutions. In addition, the bifurcation diagrams reveal a qualitative similarity to the data obtained in the Texas and Bordeaux experiments on the Belousov-Zhabotinskii chemical reaction. The paper is concluded by showing that the model can be useful for representing dynamics associated with biological and chemical phenomena.
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    The theory of population dynamics—II. Physiological delays (1988)
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    Bulletin of mathematical biology 50 (1988), S. 503-515 
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    Notes: Abstract Traditional population models describe changes in population size as a function of changes in the resources. Such first-order models cannot describe certain properties of population dynamics. General models with delays can account for all the observed dynamic complexities but are judged overgeneralized. It is proposed that the simplest model of intermediate complexity that explains such dynamic properties is a second-order model, which describes population dynamics as a function of a physiological variable, the dynamics of which in turn depends on resources. Data on accelerated decline of populations in the absence of food from experiments with brown and green hydra as well as literature data support the arguments.
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    The kinetics of solute clearance by a single tissue capillary of limited permeability: Explicit solutions of two models and their bounds (1988)
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    Bulletin of mathematical biology 50 (1988), S. 93-94 
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    Editorial: Software survey section (1988)
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    Book reviews (1988)
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    Bulletin of mathematical biology 50 (1988), S. 313-328 
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    Bulletin of mathematical biology 50 (1988), S. I 
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    Aroma production by spores ofPenicillium roqueforti on a synthetic medium (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 1-8 
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    ISSN: 1476-5535
    Keywords: Penicillium roqueforti ; Methyl ketone ; Aroma ; Buckwheat ; Volatile loss
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The synthesis of 2-heptanone from the sodium salt of octanoic acid by spores of five strains ofPenicillium roqueforti was studied. The strains showed a high disparity in kinetic behavior. The one selected, which was originally isolated from blue cheese, had a good resistance to substrate inhibition along with a good apparent biotransformation yield (close to 60%). An activator was needed in the incubation medium. The loss of activity of aging spores was reduced by the activator compounds; ethanol exhibited the highest efficiency. When spores were produced on buckwheat seeds with a solid state fermentation technique, the medium itself was an activator source. When the biotransformation reaction was carried out in a stirred aerated fermentor, the volatile loss by air-stream stripping had to be taken into account. No ketone metabolism occurred with the strain used.
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    Fermentation of cheese whey by a mixed culture ofClostridium beijerinckii andBacillus cereus (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 15-19 
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    ISSN: 1476-5535
    Keywords: Cheese whey ; Clostridium beijerinckii ; Bacillus cereus ; Fermentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Fermentation of cheese whey to produce butanol and butyric acid was carried out using a mixed culture ofClostridium beijerinkii andBacillus cereus. Fermentation selectivities were studied by controlling the pH of the system. Controlled pH values higher than 6.5 as well as those below 5.0 were not conducive to butanol production. Maximum product formation was obtained by controlling the pH at 5.5. When compared with the results obtained using the pure culture ofC. beijerinckii, a higher butanol concentration was obtained in the mixed culture without sacrificing the level of butyric acid formed.
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    Methionine inhibition of thienamycin formation (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 57-59 
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    Keywords: Thienamycin ; Methionine interference ; Streptomyces cattleya
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    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Methionine interference in the formation of thienamycin byStreptomyces cattleya is due, to a major extent, to inhibition of enzyme activity.
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    Modeling of calcium-induced solubility profiles of casein for biotechnology: Influence of primary structure and posttranslational modification (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 61-71 
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    Keywords: Casein ; Solubility profile ; Primary structure ; Posttranslational modification ; Protein functionality
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    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Molecular biology holds the promise of new tools for the food industry which include proteins with tailor-made functionality. Without a fundamental knowledge of the molecular bases of these properties, implementation will be strictly empirical. For example, the phenomena of salt-induced precipitation of proteins (salting-out) and their resolubilization (salting-in) has heretofore been discussed only qualitatively. A quantitative method, using Wyman's theory of thermodynamic linkage, has been developed and tested on the calcium-induced solubility profiles of the major milk proteins, the caseins. Salting-out was described by a salt-binding constant,k 1, andn, the number of moles of salt bound; salting-in was described by the corresponding termsk 2 andm. The magnitude of these parameters indicated involvement of protein phosphate groups in binding and precipitation, but enzymatic dephosphorylation showed significant increases ink 1 andk 2 indicating involvement of carboxylate groups as well. Studies on two genetic variants of αs1-casein indicated the importance of a hydrophobically stabilized intramolecular ion pair in the functionality of the protein. These studies have led to a fuller understanding of the molecular basis for the solubility behavior of caseins and have laid the groundwork for future computer simulation of food protein functionality.
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    Investigation of differences in the tertiary structures of food proteins by small-angle X-ray scattering (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 89-103 
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    Keywords: Food protein ; Milk protein ; Egg protein ; Protein structure, tertiary ; Small-angle scattering ; β-Lactoglobulin ; α-Lactalbumin ; Lysozyme ; Ribonuclease ; Riboflavin-binding protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary With current emphasis in bioengineering on developing new and better structure-function relationships for proteins (e.g., the need for predictability of expected properties prior to cloning), practical and reliable methodology for providing characterization of appropriate features has become of increasing importance. The most potent and detailed technique, X-ray crystallography, has severe limitations: it is so demanding and time-consuming that X-ray coordinates are frequently unavailable for materials of interest; its data relate to static and essentially unhydrated structures, whereas proteins exhibit a variety of dynamic features and function in an aqueous environment; and many proteins of technological importance may never be crystallized. Small-angle X-ray scattering, however, is particularly suitable as a methodology that can provide a substantial number of significant geometric parameters consistent with crystallographic results, that can readily show tertiary structural changes occurring under varying conditions, and that can deal with solutions and gels. Results are presented here from small-angle X-ray scattering investigations of the apo and holo forms of chicken egg-white riboflavin-binding protein, chicken egg-white lysozyme, bovine milk-whey α-lactalbumin and β-lactoglobulin, and bovine ribonuclease. We utilize these observations to compare tertiary structures of these proteins as well as conformational changes in these structures, and to provide a basis for discussion of their physical and biological significance.
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    Analysis of the biomacromolecular architecture of eukaryotic and prokaryotic serine proteases (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 127-137 
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    Keywords: Serine protease ; Limited proteolysis ; Biomacromolecular architecture ; Genetic engineering
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    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary We have been developing computational approaches to increase our ability to analyze the growing body of three-dimensional structural data with applications centered on the serine proteases and their natural inhibitors and substrates. It is essential that these approaches emphasize the comparison of these macromolecules at the separate levels of secondary, tertiary and quaternary structure. We assume in our analysis that in functionally related macromolecules (i.e., a family of evolutionarily related enzymes), regions of structural and/or physicochemical similarity will exhibit functional similarity; regions that are different in structure and/or physicochemical properties will function differently and, therefore, be the source of observed specificity. It is the intent of our research to encapsulate such ‘knowledge’ in a form which is capable of observing patterns which may serve as generalizable rules for macrostructural analysis (Liebman, M.N. 1986. Enzyme 36: 150–163), and to serve as the essential ‘tools’ for the rational design of modified serine proteases and/or their natural inhibitors by the methods available through genetic engineering.
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    The lipid composition and conversion of tryptamine toN b-acetyltryptamine in aCatharanthus roseus cell line without indole alkaloids (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 293-297 
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    ISSN: 1476-5535
    Keywords: Catharanthus roseus ; Sterol ester ; Lipid ; Indole alkaloid ; Acetyl coenzyme A ; Tryptamine ; Tryptophan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A cell line, NA13-2, was selected as a rapidly growing colony of protoplasts from a UV(254 nm)-fluorescent cell line, NA13-1, which originated from a tryptamine-resistant strain ofCatharanthus roseus NA13. Cell line NA13-2 lost the capability to produce indole alkaloids. Tryptophan fed to these cells was converted toN b-acetyltryptamine as the major product. The free acetyl coenzyme A content of NA13-2 cells was 50% higher than in the mother cells. The total lipid content of the NA13-2 cells was 2.5-fold that in the NA13 cells. In spite of the similarity in the fatty acid content to that of the mother cell line NA13, the total lipid extract of NA13-2 cells appeared as a wax instead of an oil, resulting from the presence of sterol esters.
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    Protoplast fusion inStreptomyces avermitilis (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 311-320 
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    Keywords: Recombination ; Protoplast fusion ; Streptomyces avermitilis ; Avermectin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The power of protoplast fusion as a generally applicable method for obtaining genetic recombination is demonstrated by the recombination of genes involved in avermectin biosynthesis. A backcross ofStreptomyces avermitilis strain MA6202, an improved mutant that had lost the ability to carry out the methylation of the C-5 hydroxyl of the avermectin molecule, with the original soil isolate MA4680 resulted in the recovery of at least one unambiguous recombinant class despite the instability of rifampicin resistance, one of two markers initially used for recombinant selection. Such intrinsic instability is frequently encountered in streptomycete genetics, and this result delineates the utility of protoplast fusion as a genetic tool. Other difficulties addressed include recovery of complementary recombinant classes, differences in recombination frequency due to colony density on regeneration medium, and alteration in plating efficiency on diagnostic media following protoplasting and regeneration. The results of a cross between a nicotinamide auxotroph MRG1003 and a lysine auxotroph MRG 1004 are included to aid in the elucidation of these problems as well as to support the finding of homologous recombination inS. avermitilis.
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    Anaerobic biotransformations of pollutant chemicals in aquifers (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 179-194 
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    Keywords: Aquifer ; Biodegradation, anaerobic ; Pollutant ; Groundwater ; Methanogenesis ; Sulfate-reduction ; Ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Anaerobic microbial communities sampled from either a methanogenic or sulfate-reducing aquifer site have been tested for their ability to degrade a variety of groundwater pollutants, including halogenated aromatic compounds, simple alkyl phenols and tetrachloroethylene. The haloaromatic chemicals were biodegraded in methanogenic incubations but not under sulfate-reducing conditions. The primary degradative event was typically the reductive removal of the aryl halides. Complete dehalogenation of the aromatic moiety was required before substrate mineralization was observed. The lack of dehalogenation activity in sulfatereducing incubations was due, at least in part, to the high levels of sulfate rather than a lack of metabolic potential. In contrast, the degradation of cresol isomers occurred in both types of incubations but proved faster under sulfate-reducing conditions. The requisite microorganisms were enriched and the degradation pathway forp-cresol under the latter conditions involved the anaerobic oxidation of the aryl methyl group. Tetrachloroethylene was also degraded by reductive dehalogenation but under both incubation conditions. The initial conversion of this substrate to trichloroethylene was generally faster under methanogenic conditions. However, the transformation pathway slowed when dichloroethylene was produced and only trace concentrations of vinyl chloride were detected. These results illustrate that pollutant compounds can be biodegraded under anoxic conditions and a knowledge of the predominant ecological conditions is essential for accurate predictions of the transport and fate of such materials in aquifers.
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    Pullulan production by color variant strains ofAureobasidium pullulans (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 231-239 
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    ISSN: 1476-5535
    Keywords: Aureobasidium pullulans ; Color variant ; Cornstarch ; Pullulan ; Regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Naturally occurring ‘color variant’ strains ofAureobasidium pullulans are distinguished from typical strains by their brilliant pigmentation, overproduction of secreted enzymes (xylanase), and low DNA relatedness. Color variants have not previously been examined for pullulan secretion. Among five independently isolated color variants, strains NRRL Y-12,974 and YB-4026 made the greatest amounts of pullulan from cornstarch, with conversion efficiencies of about 10%. Neither color variant nor typical strains made significant amounts of pullulan from the unconventional lactose or xylan substrates. Pullulan yields were inversely correlated with biomass production. Pullulan production thus appears to be a variable characteristic of both color variant and typically pigmented strains ofA. pullulans, regulated by specific inducers during growth limitation.
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    URL: http://dx.doi.org/10.1007/BF01569581
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    Method for the preparation of stabile microencapsulated lactic acid bacteria (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 253-257 
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    ISSN: 1476-5535
    Keywords: Granulation ; Lactic acid bacteria ; Culture ; Coating ; Microencapsulation ; Stabilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A method to produce viable and stabile dry microorganisms for food and agricultural purposes was developed. Spray-dried, freeze-dried or liquid culture concentrates of lactic acid-producing bacteria were mixed with various bulking agents to form a homogeneous wet granulation having a water content of 35–60% (w/w). The wet granulation was extruded through a dye onto a spinning plate (350–500 rpm) of a spheronizing device which resulted in the formation of discrete spherical particles. After forming spheres, the aggregate cell particles, both coated and uncoated, were dried to a moisture level of 5–10% using a temperature below the microorganism's optimum growth temperature. The coated and uncoated products were stored at different temperatures and periodically sampled to determine stability. Uncoated cell particles were more stabile at 4°C than at 22°C for 76 days. While both coated (with sodium alginate or carboxymethyl-cellulose) and uncoated particles showed similar stability at 4°C, at higher storage temperatures the applied coating improved the storage stability of the culture particles.
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    Adsorption ofTrichoderma reesei cellulases on protein-extracted lucerne fibers (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 273-280 
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    ISSN: 1476-5535
    Keywords: Adsorption ; Cellulase ; Cellulose ; Lucerne fiber ; Trichoderma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Protein-extracted lucerne fibers (PELF) had a higher adsorptive capacity forTrichoderma reesei cellulases than a variety of other cellulosic substrates compared on an equal carbohydrate basis. Adsorption at room temperature reached a maximum at about 5 min; desorption was directly proportional to the extent of carbohydrate solubilization. Cellulase binding conformed to a Langmuir isotherm; the maximum cellulasebinding capacity of PELF was 111 filter paper units per g dry weight. About 85% of the cellulase was recovered in the soluble fraction after PELF hydrolysis. Soluble carbohydrates in the hydrolysate inhibited cellulase adsorption to fresh substrate (50% inhibition at a hydrolysate concentration of 7% glucose equivalents). The effect of these carbohydrates on cellulase adsorption was a complex one composed of both enhancing and inhibitory influences. Artificial hydrolysates (known sugars in proportions identical to actual hydrolysates) inhibited adsorption, but glucose, cellobiose and xylose resulted in adsorption enhancement. Acid treatment of the hydrolysate to convert oligosaccharides to monomers increased reducing sugar concentrations and eliminated its capacity for adsorption inhibition.
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    Mechanisms of tetracycline and rifampicin resistance inBacteroides fragilis mutants obtained by ionizing radiation (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 299-304 
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    ISSN: 1476-5535
    Keywords: Anaerobe ; Antibiotic resistance ; Irradiation ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Based on a dose-survival curve, a radiation dose of 3.99 C/kg was used to induce antibiotic-resistant mutants inBacteroides fragilis. Escherichia coli B/r membrane fragments were employed as a reducing agent. Antibiotic-resistant mutants ofB. fragilis were utilized to study the mechanism by which these organisms become resistant to selected chemotherapeutic agents. Decreased accumulation of tetracycline by resistant mutants ofB. fragilis suggests that the resistance to this antibiotic is associated with the outer membrane permeability. There is a marked difference in the inhibitory action of rifampicin on RNA polymerase activity in rifampicin-sensitive and-resistant strains ofB. fragilis. This enzyme is, therefore, the likely target for inhibition of bacterial growth in this anaerobe by rifampicin.
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    Purification and characterization of a thermostable pullulanase fromThermoactinomyces thalpophilus (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 343-350 
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    ISSN: 1476-5535
    Keywords: Thermophilic actinomycete ; Actinomycete ; Debranching enzyme ; pullulanolysis ; Saccharification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Thermoactinomyces thalpophilus No. 15 produced an extracellular pullulanase in an aerobic fermentation with soluble starch, salts, and complex nitrogen sources. Acetone fractionation, ion-exchange chromatography, and gel filtration purified the enzyme from cell-free broth 16-fold to an electrophoretically homogeneous state (specific activity, 1352 U/mg protein; yield, 4%). The purified enzyme (estimated MW 79 000) was optimally active at pH 7.0 and 70°C and retained 90% relative activity at 80°C (30 min) in the absence of substrate. The enzyme was activated by Co2+, inhibited by Hg2+, and exhibited enhanced stability in the presence of Ca2+. The enzyme hydrolyzed pullulan (K m 0.32%, w/v) forming maltotriose, and hydrolyzed amylopectin (K m 0.36%, w/v), amylopectin beta-limit dextrin (K m 0.45%, w/v) and glycogen beta-limit dextrin (K m 1.11%, w/v) forming maltotriose and maltose.
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    Ammonium lactate from deproteinized alfalfa juice byStreptococcus faecium (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 373-376 
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    ISSN: 1476-5535
    Keywords: Agricultural by-product ; Fermentation ; Ammonium lactate ; Probiotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Deproteinized alfalfa juice is a by-product of the mechanical fractionation of alfalfa to obtain protein. In this work the juice was used as the substrate for the production of ammonium lactate (l-lactic acid) by a strain ofStreptococcus faecium. Batch fermentation with a constant pH of 5.8 gave 27.2 g/l of lactic acid (90% conversion and 1.1 g/l/h productivity) and 6×1012 cells/l after 24 h. Semicontinuous fermentation allowed the conversion of 3-times the volume of deproteinized juice after 44 h, finally giving 29.7 g/l of ammonium lactate (99% conversion and 2.5 g/l/h productivity) and 4–6×1012 cells/l.
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    Application of computerized infrared and Raman spectroscopy to conformation studies of casein and other food proteins (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 73-88 
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    ISSN: 1476-5535
    Keywords: Spectroscopy, computerized ; IR spectroscopy ; Raman spectroscopy ; Protein structure-function relationship ; Conformation study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The ability of modern biotechnology to produce new or modified proteins has outpaced current understanding of the relationship between protein structure and protein function. Resolution-enhanced infrared spectroscopy and Raman spectroscopy are excellent non-destructive techniques for investigating the secondary structure of proteins under a wide variety of conditions. The techniques yield rapid, reliable estimates of the proportion of helical structure, β-strands, and turns of proteins in solution, as gels, or as solids. These methodologies can also detect subtle variations in protein conformation that frequently occur upon change of the biomolecular environment. In particular, it is possible to study structural changes which arise from alterations in pH, ionic strength, nature of solvent, and from interactions with other molecules or ions, such as another protein or Ca2+ ions. The first part of this paper will briefly review various important aspects of the techniques. The subsequent part describes application to structural problems of casein and other food proteins.
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    Spheroplast formation and partial purification of microbodies from hydrocarbon-grown cells ofCladosporium resinae (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 111-117 
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    ISSN: 1476-5535
    Keywords: Cladosporium resinae ; Microbody ; Catalase ; Spheroplast ; Hydrocarbon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Cells ofCladosporium resinae form greater numbers of microbodies when grown onn-alkanes than when grown on glucose. To facilitate isolation of microbodies, hydrocarbon-grown cells were spheroplasted. Of four spheroplasting agents and five osmotic supports examined, best results were obtained after a 4-h incubation with Novozym 234 plus chitinase and with 0.8 M sorbitol as osmotic support. Equal numbers of spheroplasts were obtained at pH 5.8 and at pH 7.0. Catalase was used as a marker for microbodies and cytochrome-c oxidase as a marker for mitochondria. Urate oxidase, a second marker for microbodies, was not detected in cell extracts. Microbodies were extremely fragile; of eight spheroplast disruption techniques attempted, the best yield of microbodies was obtained using a Teflon homogenizer for 5 min. Microbodies were partially purified by differential and density gradient centrifugation. Best results were obtained with discontinuous Percoll gradients which yielded a fraction enriched in microbodies and one enriched in mitochondria.
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    Filamentous growth ofPseudomonas aeruginosa (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 139-146 
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    ISSN: 1476-5535
    Keywords: Biofilm ; Plasticity ; Adherent bacteria ; Elongation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The growth of two strains ofPseudomonas aeruginosa in stirred batch cultures was monitored by optical density, DNA concentration, and acridine orange direct cell count measurements. Growth of adherent bacteria in pure culture was also observed on suspended glass discs by light and scanning electron microscopy. Strain MUCOID produced significant numbers of filamentous cells in broth culture and in the adherent population, while strain PAO 381 did not produce elongated cells. Filamentous growth of MUCOID could be prevented by the addition of 5 × 10−2 M Mg2+. However, the addition of 0.66 mM EDTA caused an increased proportion of the population (〉50%) of MUCOID cells to become filamentous in broth culture. The results are discussed and related to theories regarding bacterial plasticity, and filamentation of normally bacillary cells.
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    Copper retention by a strain ofBacillus (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 205-209 
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    ISSN: 1476-5535
    Keywords: Copper ; Retention ; Bacillus ; Resting cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A survey has been made of the copper accumulation by resting cells of bacteria selected as copper-resistant, isolated from activated sludges. The best selected strain, classified asBacillus, retained copper at up to 3.8% of its cell dry weight. These values were lower in the presence of glucose, unlike a type culture ofBacillus cereus, in which the retention of copper was higher when glucose was present. Possible reasons for these changes in uptake of both strains are suggested.
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    Microbial metabolism and detoxification of 7,12-dimethylbenz[a]anthracene (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 211-225 
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    ISSN: 1476-5535
    Keywords: Microbial metabolism ; Fungi ; 7,12-Dimethylbenz[a]anthracene ; Cunninghamella elegans ; Syncephalastrum racemosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Six strains of fungi grown on Sabouraud dextrose broth in the presence of 7,12-dimethylbenz[a]anthracene (DMBA) were surveyed for their ability to metabolize DMBA. Experiments with [14C]DMBA indicated that the extent of formation of organic-soluble metabolites ranged from 6 to 28% after 5 days of incubation, depending on the organism tested. The yields of water-soluble metabolites also varied, and ranged from 1 to 33% after 5 days.Cunninghamella elegans ATCC 36112 andSyncephalastrum racemosum UT-70 exhibited the highest DMBA-metabolizing activity among the organisms surveyed.S. racemosum metabolized DMBA primarily to 7-hydroxymethyl-12-methylbenz[a]anthracene (7-OHM-12-MBA)_ and 7,12-dihydroxymethylbenz[a]anthracene (7,12-diOHMBA). Minor metabolites included 7-OHM-12-MBA-trans-5,6-, 8,9- and 10,11-dihydrodiols, and glucuronide and sulfate conjugates of phenolic derivatives of DMBA. In contrast, the major DMBA metabolites produced byC. elegans were water-soluble. The predominant organic-soluble metabolites produced byC. elegans included 7-OHM-12-MBA-trans-5,6-, 8,9- and 10,11-dihydrodiols. DMBA-trans-3,4-dihydrodiol was also detected. Circular dichroism spectral analysis revealed that the major enantiomer of the 7-OHM-12-MBA-trans-8,9-dihydrodiol formed by each organism has anS,S absolute configuration, while the major enantiomers of the 5,6-, 10,11- and 3,4-dihydrodiols had anR,R configuration. The mutagenic activity of extracts fromS. racemosum exposed to DMBA were determined inSalmonella typhimurium TA98. The mutagenicity of DMBA decreased by 36% over a period of 5 days as 33% of the compound was metabolized. Comparison of these results with previously reported results in mammalian systems suggests that there are similarities and differences between the fungal and mammalian oxidation of DMBA and that the overall balance of fungal metabolism is towards a detoxification rather than a bioactivation pathway.
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    Screening of yeasts for production of xylitol fromd-xylose and some factors which affect xylitol yield inCandida guilliermondii (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 241-251 
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    ISSN: 1476-5535
    Keywords: Hemicellulose ; Fermentation ; Polyol ; Pentose ; d-Xylose ; Xylitol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The ability to convertd-xylose to xylitol was screened in 44 yeasts from five genera. All but two of the strains produced some xylitol with varying rates and yields. The best xylitol producers were localized largely in the speciesCandida guilliermondii andC. tropicalis. Factors affecting xylitol production by a selectedC. guilliermondii strain, FTI-20037, were investigated. The results showed that xylitol yield by this strain was affected by the nitrogen source. Yield was highest at 30–35°C, and could be increased with decreasing aeration rate. Using high cell density and a defined medium under aerobic conditions, xylitol yield byC. guilliermondii FTI-20037 from 104 g/ld-xylose was found to be 77.2 g/l. This represented a yield of 81% of the theoretical value, which was computed to be 0.9 mol xylitol per mold-xylose.
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    An inexpensive insoluble chromogenic substrate for the determination of proteolytic activity (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 259-261 
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    ISSN: 1476-5535
    Keywords: Casein ; Chromogenic substrate ; insoluble ; Proteolytic activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A new insoluble chromogenic substrate for the determination of proteolytic activity was developed. This substrate was prepared by incorporating black drawing ink into casein and heating this complex at 200°C for 4 h. It is especially suitable for determining the activity of alkaline bacterial proteinases.
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    The use of gene probes in the rapid analysis of natural microbial communities (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 281-292 
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    ISSN: 1476-5535
    Keywords: Gene probe ; Colony hybridization ; DNA:DNA hybridization ; Community analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Hybridization probes produced from DNA sequences have proven to be a powerful tool in the rapid and sensitive analysis of natural microbial communities. By using function-specific probes, such as those identifying genes coding for photosynthesis, the potential a microbial community has for performing a given function may be rapidly determined. Gene probes have also been used in the identification and isolation of a specific catabolic genotype in less than one-fourth the time required for the conventional culture enrichment technique. Species-specific probes constructed from portions of genes coding for ribosomal RNA have been used for the rapid identification and enumeration of bacterial species in environmental samples. The use of reassociation kinetics as a measure of community diversity and complexity is also discussed. The successful application of this technique to community analysis may reduce the time required from 1 year, for conventional analysis, to 2 weeks.
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    Proteins as potential bacterial growth inhibitors in foods: Suppression of the activity of water by proteins as determined by NMR relaxation methods (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 147-155 
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    ISSN: 1476-5535
    Keywords: Bacterial growth retardation ; Suppression of the activity of water ; Protein hydration ; Deuterium NMR relaxation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Food microbiologists have long known that suppression of the activity of water,a w, can retard microbial growth in food systems. Traditionally,a w, suppression has been achieved by addition of salts or humectants to foods. To limit the amount of preservatives added to food products, studies were initiated to assess the feasibility of using proteins to suppressa w to a practical value for retarding bacterial growth and to determine the optimum environmental condition for maximizing this effect for milk proteins. New expressions were developed relating observed longitudinal and transverse NMR relaxation rates, in the absence of cross-relaxation, to protein hydration $$\bar \upsilon _w $$ , to the protein activity coefficient, γp, and to the correlation time of the bound water, τc. From γp, the second virial coefficient of the protein,B o, can be found. By use of $$\bar \upsilon _w $$ andB o,a w could then be directly evaluated at any protein concentration. Resulting expressions were tested by2H-NMR relaxation measurements made as a function of protein concentration, for: β-lactoglobulin A (the major whey protein) under nonassociating (pH 6.0) and associating (pH 4.65) conditions; and for casein (the major milk protein) in the micellar (with added Ca2+) and submicellar (without Ca2+) forms. Values ofa w calculated from these2H-NMR data show that casein, at all the concentrations and temperatures examined, suppressesa w more than does β-lactoglobulin A because of a largerB o. In turn, micellar casein suppressesa w to a larger extent than does submicellar casein because of a larger $$\bar \upsilon _w $$ . Extrapolation ofa w at 4°C to a concentration ten times that in normal milk yields a value, ofa w of less than 0.95, at whichSalmonella and some strains ofClostridium botulinum no longer grow. These results are in agreement with what is known about storageability of condensed milk. Generalizations regarding the types of proteins and cosolutes to be used for suppressinga w will be discussed. Structural information on these proteins calculated from τc will also be presented.
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    Trichothecene biosynthesis inGibberella pulicaris: Inheritance of C−8 hydroxylation (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 167-174 
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    ISSN: 1476-5535
    Keywords: Trichothecene ; Gibberella pulicaris ; Fusarium sambucinum ; Diacetoxyscirpenol ; Acetylneosolaniol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Naturally occurring strains ofGibberella pulicaris (Fusarium sambucinum) produce different kinds and levels of trichothecene toxins. Progeny from crosses between strains which produce trichothecenes with an oxygen-containing group at C−8 (C8+) and those that do not (C8−) can segregate in a 1∶1 ratio for this trait. These results define a genetic locus, which we have designatedTox1. The segregation patterns observed for progeny obtained from crosses between high-toxin producers and low-toxin producers indicate that the level of toxin production is determined by several loci. One gene which controls quantitative aspects of toxin production segregates independently of both theTox1 locus and another locus which controls toxin levels. These results suggest that multiple, unlinked nuclear loci are involved in the control of trichothecene biosynthesis.
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    Microbial transformations of tin and tin compounds (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 195-204 
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    ISSN: 1476-5535
    Keywords: Tin ; Microbial transformation ; Methylation of tin ; Methyltin ; Butyltin ; Organotin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The use of organotins for agricultural and industrial purposes and in the marine environment has been increasing steadily for more than 20 years. Recently, reliable methodologies have been developed to permit quantification of individual molecular species of organotins in cultures and in the environment. Particular attention has been given to methyltins which can be formed abiotically and by microorganisms, and to tributyltins which are toxic components of effective antifouling paints. In the aquatic environment tin, tributyltins and other organotins accumulate in the surface microlayer, in sediments, and on suspended particulates. Tin compounds are toxic to a variety of organisms and some aquatic organisms can bioaccumulate them. When tin compounds, particularly di-or tri-substituted tins, enter an ecosystem, a portion of the microbial population is killed. Among the survivors are organisms which can methylate inorganic or organic tins, but the relative contribution of biotic and abiotic mechanisms is not clear. While many details of methylations and demethylations need to be worked out, it is clear that transformations of tins can influence the toxicity, volatility and mobility of tin in natural ecosystems. Tributyltins can be debutylated by microorganisms, and hydroxybutyl tins may be intermediates, as they are in mammalian systems. Little is known of the potential and probable microbial transformations of other economically important organotins, but the transformations should be studied for they may have industrial and environmental importance.
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    A rapid and simple method for staining of the crystal protein ofBacillus thuringiensis (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 227-229 
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    ISSN: 1476-5535
    Keywords: Bacillus thuringiensis ; Crystal protein ; δ-Endotoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A rapid and simple method of staining for the crystal protein (δ-endotoxin or parasporal body) ofBacillus thuringiensis has been developed. Changes in colonial morphology were observed when cells lost their ability to form crystal protein or both crystal protein and spore.
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    Conversion of cyanide to formate and ammonia by a pseudomonad obtained from industrial wastewater (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 263-272 
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    ISSN: 1476-5535
    Keywords: Adaptation to cyanide ; Cyanide degradation ; Formate ; Pseudomonad ; Industrial wastewater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A cyanide-degrading pseudomonad was isolated by selective enrichment in a chemostat inoculated with coke-plant activated sludge and maintained at a dilution rate of 0.042/h for 60 days with a feed of 10 mg/l cyanide. The isolate, a facultative methylotroph capable of growth on methanol and methylamine, degraded cyanide to formate and ammonia; it could utilize the released ammonia as a nitrogen source but did not further metabolize formate under the experimental conditions employed. Both cyanide-degrading enzyme activity and respiratory resistance to cyanide were inducible and were enhanced by repeated exposure to the compound. Cell-free extracts stoichiometrically converted cyanide to formate and ammonia in a reaction that did not require oxygen. Enzyme activity, lost upon dialysis, was restored by less than equimolar ratios of NAD(P)H or ascorbate to cyanide, indicating that the reductants did not function directly as co-enzymes.
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    Direct utilization of lactose in clarified cheese whey for xanthan gum synthesis byXanthomonas campestris (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 321-328 
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    ISSN: 1476-5535
    Keywords: Tn951 lactose gene ; Chromosomal integration vector ; Exopolysaccharide production ; Xanthan gum ; Cheese whey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A derivative ofXanthomonas campestris B1459 was constructed that utilizes lactose in clarified cheese whey for xanthan gum synthesis. Genes conferring lactose utilization carried by transposon Tn951 were inserted into the bacterial chromosome. The ability to use lactose for xanthan gum synthesis was stably inherited and the amount of xanthan produced suggested carbohydrate conversion efficiencies similar to wild-typeX. campestris growing in the presence of glucose. Bench-scale fermentation of this organism and identification of the optimal whey sources and pretreatments can now proceed.
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    URL: http://dx.doi.org/10.1007/BF01569533
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    Microbial accumulation of neptunium (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 329-331 
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    ISSN: 1476-5535
    Keywords: Neptunium ; Metal uptake ; Microorganism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Resting cells of several species of microorganisms removed neptunium (Np) from an aqueous solution. Concentrations of up to 15 mg Np per g cells (dry weight) were obtained. Maximum uptake byMicrococcus luteus occurred in less than 10 min.
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    Effect of aeration on antibiotic production byStreptomyces clavuligerus (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 357-364 
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    ISSN: 1476-5535
    Keywords: Cephamycin C ; Dissolved oxygen ; Streptomyces ; Batch fermentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary During the rapid growth phase ofStreptomyces clavuligerus in a 10 litre fermentor, the level of dissolved oxygen (DO) was found to drop to almost zero for a period of approximately 10 h, delaying the appearance of and lowering the production of the antibiotic cephamycin C. Controlling the DO at either 50% or 100% throughout the fermentation did not significantly alter the specific growth rate of the culture, but did elevate final antibiotic levels two- and three-fold respectively. The improved oxygen availability affected antibiotic production both by increasing the rate of specific cephamycin C bisosynthesis and by maintaining this higher rate throughout the production period. These results demonstrate that controlling dissolved oxygen levels close to saturation during periods of rapid growth markedly improves the efficiency and duration of cephamycin C biosynthesis inS. clavuligerus.
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    URL: http://dx.doi.org/10.1007/BF01569557
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    Mycotoxigenic isolates and toxin production on buckwheat and rice hulls used as bedding materials (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 351-356 
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    ISSN: 1476-5535
    Keywords: Mycotoxin ; Aflatoxin ; Trichothecene ; Upholstery ; Rice and buckwheat hulls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A pre-evaluation of the samples of both buckwheat and rice hulls, planned for use as pillow fill-materials, showed the presence ofAspergillus flavus, A glaucus, andPenicillium spp. Buckwheat- and rice-hull media (BHM and RHM) inoculated withA. flavus both supported the production of aflatoxins (AFB1 and AFG1) in the parts per million (ppm) range; BHM yielded approximately twice the quantity of both AFB1 and AFG1 than did RHM. Both BHM and RHM inoculated withFusarium tricinctum yielded trichothecenes (T-2 toxins) in the ppm range, with the BHM producing approximately three times more T-2 toxins than the RHM. Also,F. tricinctum grown on both media produced several metabolites which included HT-2, 3′-OH T-2, neosolariol, T-2 triol, and T-2 tetraol. The BHM yielded all of the above, while the RHM failed to support the production of the 3′-OH T-2 toxin. In addition, neither medium inoculated withMyrothecium roridum yielded any detectable levels of macrocyclic trichothecenes. The results indicated that these materials have the potential to become contaminated with mycotoxins.
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    URL: http://dx.doi.org/10.1007/BF01569556
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    Thermotolerant single cell protein production byKluyveromyces marxianus var.marxianus (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 9-14 
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    ISSN: 1476-5535
    Keywords: Single cell protein ; Sucrose ; Yeast ; Thermotolerance ; Fermentation ; Kluyveromyces marxianus var.marxianus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Amino acid analyses were undertaken on single cell protein (SCP) produced by thermotolerant strains ofKluyveromyces marxianus var.marxianus grown on sugar cane molasses at 40°C. The maximum conversion of available sugars to biomass at 45°C was only 10.8% (g dry wt.·g−1 total sugars). The amino acid composition of the SCP did not differ markedly from that reported for other yeast species.
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    Effect of polymer differences on fungal penetration of hydrogel lenses (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 29-32 
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    ISSN: 1476-5535
    Keywords: Hydrogel lens ; Fusarium solani ; Curvularia lunata ; Fungi ; Growth in hydrogel lenses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Two chemically distinct types of hydrogel lenses, vifilcon A and bufilcon A, each with a water content of 55%, were challenged in a balanced salts solution withAspergillus fumigatus, Cladosporium cladosporioides, Curvularia lunata andFusarium solani. The lenses were cleaned, disinfected and stained after varying periods of incubation and examined with light microscopy and scanning electron microscopy. For three of the four fungi, the bufilcon A lens was more susceptible to fungal attack than the vifilcon A lens.Curv. lunata produced the greatest number of penetration pegs within 72 h for both lens types. Etching of lens surfaces was observed withC. cladosporioides. In general, the susceptibility of a hydrogel lens to penetration with a fungus appeared to vary with the species of fungus and the chemical composition of the lens.
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    Characterization of the effect of aluminum metal on poliovirus (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 33-38 
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    ISSN: 1476-5535
    Keywords: Aluminum ; Virus ; Poliovirus ; Inactivation ; Disinfection ; Water treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Metallic aluminum has been studied for possible use in conjunction with or as an alternative to conventional soluble disinfectants as applied to drinking and wastewater. Acid-washed aluminum was incubated with [35S]methionine-labeled poliovirus type 1 (LSc) and the counts per min (cpm)/plaque-forming units (pfu) ratio was determined. After 2 h, only 0.013% of the cpm remained in solution, indicating viral adsorption onto the surface of the aluminum. After 76 h, 93% of the cpm returned to solution, while infectivity dropped from 2.2×107 pfu/ml to undetectable levels. This suggests that infectious viruses were adsorbed onto the aluminum surface and released from the surface of the aluminum as non-infectious particles. Analysis by electron microscopy, cesium chloride gradient and polyacrylamide gel electrophoresis indicates that either dissociation or destruction of the viral capsid proteins occurs during incubation with aluminum, which results in viral inactivation.
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    Experimental formulations ofBacillus sphaericus for the control of anopheline and culicine larvae (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 39-47 
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    ISSN: 1476-5535
    Keywords: Bacillus sphaericus ; Bacillus thuringiensis varisraelensis ; Anopheles ; Culex ; Psorophora columbiae ; Microbial control ; Formulation ; Persistence of larvicidal activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Four experimental formulations ofBacillus sphaericus Neide (2362 isolate) were evaluated for larvicidal activity against culicine and anopheline larvae in several natural and artificial habitats. A granular formulation (5% primary powder) was tested against natural populations of mosquitoes in two simulated habitats in Florida and in maturing and reflooded rice fields in Louisiana. Larvae ofCulex quinquefasciatus Say were reduced by 97 and 99% after application of the granules at the rate of 10 kg/ha to polluted tanks and 2.5 kg/ha to sod-lined potholes, respectively. Anopheline andPsorophora columbiae (Dyar and Knab) larvae were reduced by 68 and 92–100%, respectively, after application of 5 kg granules/ha to rice fields. A flowable concentrate (12.8% primary powder) applied to unpolluted and organically enriched habitats in Florida at 0.25 kg/ha reduced populations ofCulex spp. by 93–100% and 99%, respectively. Sustained-release briquets (5% primary powder) applied at the rate of one half briquet/1.8 m2 sod-lined potholes reduced larval populations ofCx. quinquefasciatus by 88–95% for up to 2 weeks in open sunlight. Sustained-release pellets (30% primary powder) applied to small woodland pools in Memphis, TN at the rate of four pellets/pool virtually eliminated larval populations ofCx. restuans Theobald for over 8 days. Variable persistance of larvicidal activity was noted for the other treatments depending on the formulation, target species and habitat.
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    Heat-induced injury inListeria monocytogenes (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 105-110 
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    ISSN: 1476-5535
    Keywords: Heat-induced injury ; Listeria monocytogenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Heating ofListeria monocytogenes (Scott A strain) in potassium phosphate buffer (0.1 M, pH 7.2) at 52°C for 1 h led to injury, with the heat-injured cells failing to produce colonies on agar medium containing 5% NaCl. The detection of injury was based on the use of differential media: plating on tryptose phosphate broth+2% agar and 1% sodium pyruvate (TPBA+P) and on tryptose phosphate broth+2% agar and 5% NaCl (TPBA+S). Only non-injuredListeria formed colonies on TPBA+S whereas both heat-injured and non-injured cells formed colonies on TPBA+P. The bacterial count on TPBA+P minus that on TPBA+S represents the extent of heat injury. A large number of selective agars were tested and compared to TPBA+P for their ability to support repair and colony formation of heat-injuredL. monocytogenes. Media containing 0.025% phenylethanol, 0.0012–0.0025% acriflavin, 0.1–0.2% potassium tellurite, 0.001% polymyxin B sulfate, 5% NaCl or a combination of these ingredients were detrimental to the recovery of heat-injuredL. monocytogenes. Media currently in use forL. monocytogenes are not satisfactory for the recovery of injured cells.
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    Fluorometric analysis of iodinated aflatoxin in minicultures ofAspergillus flavus andAspergillus parasiticus (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 119-125 
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    ISSN: 1476-5535
    Keywords: Aflatoxin miniassay ; Fluorescence analysis ; Aspergillus flavus ; Aspergillus parasiticus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A convenient miniassay for aflatoxin has been developed for cultures ofAspergillus flavus andA. parasiticus grown for 3–10 days in 10 ml of a coconut extract medium. The sensitivity of the assay, as measured by photofluorometry (365 nm maximum excitation; 445 nm maximum emission), is of the order of 0.01 μM (3.12 ng/ml) for aflatoxin B1 dissolved in aqueous iodine (0.26 mM). High performance liquid chromatography, monitored by fluorometric analysis of both an aflatoxin B1 standard and selected culture filtrates, confirmed the sensitivity of the assay and indicated specificity for iodine-enhanced fluorescence of aflatoxin in the coconut extract medium. Thin layer chromatography further confirmed the aflatoxin titers and the specificity for enhancement of aflatoxins B1 and G1 in culture filtrates.
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    Quality assurance of monoclonal products: Virologic and molecular biologic considerations (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 157-165 
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    ISSN: 1476-5535
    Keywords: Code of Federal Regulations ; DNA ; Factor 8 ; Food and Drug Administration ; Human immunodeficiency virus ; Infectious bovine rhinotracheitis virus ; Monoclonal antibody ; Polynucleotide ; Safety test ; Sindbis virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The FDA has set limits concerning the viral and molecular contamination of monoclonal antibody products intended for human use. Industry has an obligation to be as familiar with these limits as it has been with federal requirements pertaining to pyrogens and bacteria. The assessment of risk from polynucleotides, based on molecular biologic and existing technical limitations, is discssed, as is the strategy of validating the purification of monoclonal antibodies of viral contaminants in terms of an indicator organism concept.
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    Fermentation of starch hydrolysates byLactobacillus plantarum (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 175-178 
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    ISSN: 1476-5535
    Keywords: Bacterial α-amylase ; Amyloglucosidase ; Starch hydrolysate ; Tapioca ; Lactobacillus plantarum ; Lactic acid fermentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Lactic acid production by an isolated ofLactobacillus plantarum was standardised on enzyme-hydrolysed tapioca (Manihot esculenta) flour, tapioca starch and soluble starch. Calculated yields of lactic acid (g from 100 g reducing sugars used) in nutrient media containing the abovementioned hydrolysates (10% reducing sugars) were 21.8%, 16.2% and 16.2%, respectively. Higher yields (29–34%) were obtained in media containing 5% reducing sugars. A conversion efficiency of 80–99% was achieved when the acid produced in the broth was neutralised periodically. One hundred milliliters of the medium (5% sugars) yielded 4.0–4.5 g of calcium lactate. These results indicate that unrefined starchy material can be successfully employed for the economic production of lactic acid. The same substrate can also be utilised for biomass production, as viable lactobacilli are being used for therapy in medicine.
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    Evaluation of the growth of microorganisms on diaper absorbent materials (1988)
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 21-28 
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    ISSN: 1476-5535
    Keywords: Diaper ; Staphylococcus aureus ; Escherichia coli ; Candida albicans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Methods were developed to study the effects of absorbent materials from diapers on microbial survival, growth and toxic shock syndrome toxin-1 (TSST-1) production under specified in vitro conditions. Growth of representative skin and fecal flora organisms was equivalent in cultures in which materials from cotton cloth diapers, disposable diapers or disposable diapers containing absorbent gelling material were added as the sole carbon source. In urine used as an enrichment medium, growth of the test organisms in media containing material from the three diaper types was equivalent and no contribution to growth from the diaper material was detected. TSST-1 was not produced byStaphylococcus aureus under conditions in which urine was added to the diaper materials. Pathogenic strains of organisms purposefully introduced onto diapers failed to survive and the few microbial cells normally found in diaper material did not multiply when stored under conditions favorable to microbial growth. The data indicate that all three diaper types tested were the same with respect to growth and survival of representative skin and fecal organisms.
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    Buffering as a means for increasing growth and butanol production byClostridium acetobutylicum (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 49-55 
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    ISSN: 1476-5535
    Keywords: Clostridium acetobutylicum ; Buffering capacity ; Butyric acid ; undissociated
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The objective of this work was to optimize butanol formation in the acetone-butanol-ethanol (ABE) fermentation by examining the level of buffering as it affects the dissociation of butyric acid to the less toxic butyrate anion. Experiments were carried out in batch culture using chemically defined (P2) or complex media containing various buffering agents. These included salts of acetate, citrate, phosphate, nitrate, or bicarbonate, representing a range of pK a values and buffering capacities. Growth in highly buffered medium was found to increase the stationary phase cell density, carbohydrate utilization, and the final butanol concentration. At higher levels of buffering, increased growth and elevated concentrations of butyric acid were required to initiate solventogenesis, suggesting the involvement of a critical threshold level of undissociated butyric acid.
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    Comparative analysis of three recursive real-time river flow forecasting models: deterministic, stochastic, and coupled deterministic-stochastic (1988)
    Springer
    Stochastic environmental research and risk assessment 2 (1988), S. 17-33 
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    ISSN: 1436-3259
    Keywords: River flow forecasting ; discrete linear cascade model ; ARMAX ; coupled models ; Kalman filtering ; Danube
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The objective of the paper is to compare three recursive linear state space models used to forecast river flow. The three models are as follows: (i) Purely deterministic discrete linear cascade model (DLCM); (ii) Purely stochastic autoregressive moving average (ARMAX) time series model; and (iii) Coupled deterministic (DLCM) — stochastic (ARMA) model. Description of DLCM is given shortly. The state space formulation of the ARMAX model enables the recursive estimation of random walk parameters and the forecast of flows by linear Kalman filtering. The correlated error sequence of DLCM is described by an ARMA model. The DLCM and ARMA models are put together in a coupled deterministic-stochastic model. The recursive conditional forecasting of the augmented state vector is performed by the linear Kalman-filter. The conditional output forecast is given by linear projection of thea priori state vector. Numerical investigations on River Danube data lead to the conclusion that the coupled deterministic-stochastic model is the most efficient forecasting model of all the three recursive techniques compared.
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    URL: http://dx.doi.org/10.1007/BF01544191
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    Estimation of autocorrelation in a binary time series (1988)
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    Stochastic environmental research and risk assessment 2 (1988), S. 61-72 
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    ISSN: 1436-3259
    Keywords: Binary data ; censored observations ; autocorrelations ; acid rain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The properties of the well known estimator of the transition probabilities in a binary time series are investigated. A formula for the variance is obtained, which generally involves a double integral. However, in the case when the binary series is obtained by hard clipping of an AR(1) process, a good and fairly simple approximation is derived. In the MA(1) or MA(2) case exact formulae for the variance is given. In the appendix an excellent approximation to the fourth order cumulant of a clipped AR(1) process is derived, which may be of interest in other applications as well.
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    The historically adjusted range and the historically rescaled adjusted range (1988)
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    Stochastic environmental research and risk assessment 2 (1988), S. 175-188 
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    ISSN: 1436-3259
    Keywords: Reservoir storage ; range ; adjusted range
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract It was remarked by Hurst in 1951 that the adjusted range gives the size of the smallest reservoir capable of providing a constant discharge equal to the mean inflow. Since that time this range and its rescaled modification, the Hurst range, have been widely discussed, not however primarily with a view to applying them to reservoir design problems, but rather on account of their possible relevance to the simulation of geophysical time series. Acknowledging the well-known conceptual weaknesses of adjusted ranges and the theoretical difficulties that inhibit their direct utilisation in the design and operation of real reservoirs, the authors argue that the interest displayed on ranges during the past few decades justifies the effort of eliminating one in particular of these weakness, namely their non-implementability as operating policies, a consequence of the fact that they can only be retrospectively evaluated. The paper proposes modifications in which the unknowable mean and standard deviation of future samples are replaced by the known mean and sample standard deviation of historical data, leading to the historically adjusted range and the historically rescaled and adjusted range. The latter is produced as an implementable approximation to Hurst's (1951) solution to the optimal reservoir problem. The expected values of the new ranges are evaluated and numerically tabulated.
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    A geostatistical approach for areal rainfall statistics assessment (1988)
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    Stochastic environmental research and risk assessment 2 (1988), S. 245-261 
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    ISSN: 1436-3259
    Keywords: Geostatistics ; areal rainfall distribution ; areal reduction factor ; Gumbel distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Areal rainfall statistics are more relevant in flood hydrology and water resources management than point rainfall statistics when it comes to help designing dams or hydraulic structures. This paper presents a geostatistically based method to derive the areal statistics from point statistics. Assuming that the distribution models of point rainfall and areal belong to the same class of models and that the rainfall process is stationary, it is shown how the parameters of the areal distribution model can directly be computed from the parameters of the point distribution models in case of a non stationary process, an approximation is derived that yielded good results when applied to a mountainous region in Southern France. The method also allows the computation of the areal reduction factors in a very general form.
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    Modeling long term lake variations by physically based stochastic dynamic models (1988)
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    Stochastic environmental research and risk assessment 2 (1988), S. 303-315 
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    ISSN: 1436-3259
    Keywords: Physically based stochastic models ; stochastic dynamic models ; statistical predictability ; internannual variability ; ARMA models ; water level variations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Several physically based stochastic dynamic models (SDM) are described including year-to-year variations of water volume in terminal and non-terminal lakes, streamflow of lake-fed rivers, and salinity of an inland sea (the Sea of Azov). All of these models are based upon the SDM of water volume of terminal lakes developed by Kritzky and Menkel in 1946 in co-operation with Kolomogorov. Explicit formulae are derived for second order statistical moments of the output processes, including variance, correlation function, spectra, etc., under the assumption that the forcing functions from stationary random sequences. The least-squares prediction problem is solved for both stationary and non-stationary cases. Some of the processes are shown to possess high statistical predictability. Actual predictions are compared with independent observations. Problems for further study are stated.
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    On the method of maximum likelihood estimation for the log-Pearson type 3 distribution (1988)
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    Stochastic environmental research and risk assessment 2 (1988), S. 155-160 
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    ISSN: 1436-3259
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
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    URL: http://dx.doi.org/10.1007/BF01543458
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    The generalized method of moments as applied to the generalized gamma distribution (1988)
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    Stochastic environmental research and risk assessment 2 (1988), S. 161-174 
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    ISSN: 1436-3259
    Keywords: Floods ; estimation ; quantiles ; generalized gamma ; generalized moments ; standard error
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The generalized gamma (GG) distribution has a density function that can take on many possible forms commonly encountered in hydrologic applications. This fact has led many authors to study the properties of the distribution and to propose various estimation techniques (method of moments, mixed moments, maximum likelihood etc.). We discuss some of the most important properties of this flexible distribution and present a flexible method of parameter estimation, called the “generalized method of moments” (GMM) which combines any three moments of the GG distribution. The main advantage of this general method is that it has many of the previously proposed methods of estimation as special cases. We also give a general formula for the variance of theT-year eventX T obtained by the GMM along with a general formula for the parameter estimates and also for the covariances and correlation coefficients between any pair of such estimates. By applying the GMM and carefully choosing the order of the moments that are used in the estimation one can significantly reduce the variance ofT-year events for the range of return periods that are of interest.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01550839
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    Electronic Resource
    Evaluation of flow probabilities in run-off detention ponds (1988)
    Springer
    Stochastic environmental research and risk assessment 2 (1988), S. 239-244 
    Details
    ISSN: 1436-3259
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01550844
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