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1

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Buoyant density changes due to intracellular content of sulfur in Chromatium warmingii and Chromatium vinosum (1984)

Guerrero, Ricardo ; Mas, Jordi ; Pedrós-Alió, Carlos

Springer

Archives of microbiology 137 (1984), S. 350-356

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ISSN: 1432-072X

Keywords: Buoyant density ; Percoll ; Intracellular sulfur ; Chromatium warmingii ; Chromatium vinosum

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Average specific density of individual cells of pure cultures of Chromatium warmingii and Chromatium vinosum were measured by isopicnic gradient centrifugation with Percoll during growth at constant illumination as a function of the increasing content of intracellular sulfur. Cell number and volume, bacteriochlorophyll a, sulfide, and sulfur were followed in the cultures along with cellular buoyant density. Poly-β-hydroxybutyrate was monitored at several points during growth of the cultures. The density of C. warmingii changed from 1.071 to 1.108 g cm-3 (sulfur content per cell varied from 0 to 1.71pg). C. vinosum changed its density from 1.096 to 1.160 g cm-3 (sulfur content per cell varied from 0 to 0.43 pg). Maximum sulfur content in pg of sulfur per μm3 of cell volume were 0.178 for C. warmingii and 0.294 for C. vinosum. Measurement of the differences in buoyant density, volume and sulfur content before and after ethanol extraction of cells with and without intracellular sulfur, allowed tentatively to estimate the density of sulfur inside the cells as 1.219 g cm-3. Isolation of sulfur globules and centrifugation in density gradients gave a density higher than 1.143 g cm-3 for these intracellular inclusions.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00410733

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2

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Phosphate-limited growth of Chromatium vinosum in continuous culture (1992)

Mas, Jordi ; Gemerden, Hans

Springer

Archives of microbiology 157 (1992), S. 135-140

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ISSN: 1432-072X

Keywords: Chromatium vinosum ; Phosphate ; Nutrient limitation ; Continuous culture ; Phototrophic bacteria

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Chromatium vinosum DSM 185 was grown in continuous culture at a constant dilution rate of 0.071 h-1 with sulfide as the only electron donor. The organism was subjected to conditions ranging from phosphate limitation (S R-phosphate=2.7 μM and S R-sulfide=1.8 mM) to sulfide limitation (S R-phosphate=86 μM and S R-sulfide=1.8 mM). At values of S R-phosphate below 7.5 μM the culture was washed out, whereas S R-phosphate above this value resulted in steady states. The saturation constant (K μ) for growth on phosphate was estimated to be between 2.6 and 4.1 μM. The specific phosphorus content of the cells increased from 0.30 to 0.85 μmol P mg-1 protein with increasing S R-phosphate. The specific rate of phosphate uptake increased with increasing S R-phosphate, and displayed a non-hyperbolic saturation relationship with respect to the concentration of phosphate in the inflowing medium. Approximation of a hyperbolic saturation function yielded a maximum uptake rate (V max) of 85 nmol P mg-1 protein h-1, and a saturation constant for uptake (K t) of 0.7 μM. When phosphate was supplied in excess 8.5% of the phosphate taken up by the cells was excreted as organic phosphorus at a specific rate of 8 nmol P mg-1 protein h-1.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00245281

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3

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Acclimation of the photosynthetic response of Chromatium vinosum to light-limiting conditions (1998)

Sánchez, Olga ; van Gemerden, Hans ; Mas, Jordi

Springer

Archives of microbiology 170 (1998), S. 405-410

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ISSN: 1432-072X

Keywords: Key words Purple sulfur bacteria ; Light limitation ; Photosynthetic response

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract The photosynthetic response of the purple sulfur bacterium Chromatium vinosum DSM 185 to different degrees of illumination was analyzed. The microorganism was grown in continuous culture, and samples were taken from the effluent of the culture and incubated at different irradiances to determine the specific rate of sulfur oxidation as a measure of the photosynthetic activity of the organism. The activities obtained were plotted as a function of the specific rate of light uptake, and for each set of data a photosynthesis equation was fitted, which allowed the estimation of Pmax (photosynthetic capacity), qk (the threshold irradiance for light limitation), and m (maintenance coefficient). The results indicated that cells grown under light limitation are able to achieve higher photosynthetic activities than cells grown under light saturation. The photosynthetic capacity (Pmax) remained constant under all the conditions of illumination tested, while the maintenance expenses (m) were higher under light limitation. The parameter qk, on the contrary, decreased considerably at limiting irradiances.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002030050660

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4

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The influence of poly-β-hydroxybutyrate accumulation on cell volume and buoyant density in alcaligenes eutrophus (1985)

Pedrós-Alió, Carlos ; Mas, Jordi ; Guerrero, Ricardo

Springer

Archives of microbiology 143 (1985), S. 178-184

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ISSN: 1432-072X

Keywords: Alcaligenes eutrophus ; PHB ; Cell volume ; Cell density ; Percoll

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Accumulation of poly-β-hydroxybutyrate (PHB) was studied in Alcaligenes eutrophus strain N9A. Under nitrogen limitation and heterotrophic conditions, the cells accumulated PHB at a rate of 50 fg cell-1 h-1. Volume increased from 1.208 to 3.808 μm3 and buoyant density from 1.110 to 1.145 pg μm-3 with an increase in PHB from 0 up to 1.699 pg cell-1. Volume was found to change linearly with PHB content. The changes were due to increases in cell width and not in cell length. PHB explained 93% of the changes in cellular volume. The relationship between density and PHB was hyperbolic. PHB explained 96% of the changes in density. When a mutant strain unable to accumulate PHB was analyzed together with the wild type, the PHB-less mutant and the wild type showed densities of 1.100 pg μm-3 and 1.120 pg μm-3, respectively, in gradients of 65% Percoll. In sucrose gradients, nevertheless, the results were reversed. This discrepancy was explained by the high osmolarity of sucrose which gives artificial results. Thus, we conclude that Percoll is a more suitable medium than sucrose to measure the density of live bacterial cells.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00411044

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5

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Identification of phototrophic sulfur bacteria through the analysis of lmwRNA band patterns (1998)

Casamayor, E. O. ; Calderón-Paz, Juan I. ; Mas, Jordi ; [et al.]

Springer

Archives of microbiology 170 (1998), S. 269-278

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ISSN: 1432-072X

Keywords: Key words Phototrophic sulfur bacteria ; Chromatiaceae ; Identification ; lmwRNA ; 5S RNA ; tRNA ; Taxonomic relationships

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Several phototrophic sulfur bacteria were identified preliminarily through the analysis of the low-molecular-weight RNA fraction (lmwRNA) of bacterial cells. This fraction includes the ribosomal 5S RNA and several transfer RNAs. These molecules were separated by high-resolution electrophoresis in polyacrylamide gels, and the resulting band patterns were used as fingerprints for the identification of the organisms. We examined a large number of well-characterized reference strains together with a broad range of purple sulfur bacterial isolates from freshwater and marine environments. A cluster analysis was run using the similarity matrix calculated from the band patterns. Despite the shortcomings of the method, close relatives were clustered together yielding a number of groups consistent with the phylogenetic arrangement established through the analyses of a few available 16S rRNA gene sequences. Thus, the classification obtained gives further support to rearrangement of the group as the analyses of 16S rRNA gene sequences had previously suggested. We conclude that the analysis of lmwRNA band patterns is a rapid and simple tool for grouping and preliminarily identifying new isolates of phototrophic sulfur bacteria.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002030050642

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6

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In situ specific loss and growth rates of purple sulfur bacteria in Lake Cisó (1990)

Mas, Jordi ; Pedrós-Alió, Carlos ; Guerrero, Ricardo

Oxford, UK : Blackwell Publishing Ltd

FEMS microbiology letters 73 (1990), S. 0

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ISSN: 1574-6968

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Abstract Growth rates and population dynamics of phototrophic bacteria in Lak Cisó were analysed by measuring bacterial abundances and determining specific rates of growth and loss. Net growth rates were calculated from actual changes in biomass assuming exponential growth. Values ranged between −0.072 and 0.037 per day (d−1) for Chromatium, and between −0.043 and 0.022 d−1 for Amoebobacter. Exponential loss rates through sedimentation, decomposition and washout were determined independently. Values ranged between 0 and 0.025 d−1 in the case of Chromatium and between 0 and 0.015 d−1 in the case of Amoebobacter. Finally, gross growth rates were calculated by adding net growth to losses. Maximal values were 0.063 d−1 for Chromatium and 0.037 d−1 for Amoebobacter. In the case of Chromatium, population growth rates were found to be correlated with the amount of light available per unit of growing biomass. It was concluded that growth of phototrophic bacteria in Lake Cisó was limited by light availability. Altogether, purple sulfur bacteria seemed to maintain a very large biomass with very slow growth, thanks to very slow losses during stratification. During holomixis the situation was more dynamic. Washout of cells and disappearance of algal cells allowed more light to reach the bacteria. Therefore, high growth rates were found towards the end of the winter. A similar pattern repeated itself from year to year. These are the first estimates of in situ growth rates for populations of phototrophic bacteria.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1574-6968.1990.tb03950.x

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7

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Variations in cell size and buoyant density of Escherichia coli K12 during glycogen accumulation (1989)

Mas, Jordi ; Pedrós-Alió, Carlos ; Guerrero, Ricardo

Oxford, UK : Blackwell Publishing Ltd

FEMS microbiology letters 57 (1989), S. 0

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ISSN: 1574-6968

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Abstract The effect of glycogen accumulation on buoyant density and volume of Escherichia coli K12 was studied. A procedure consisting of three linear equations is presented. This requires measurement only of three parameters: cell buoyant density, cell volume and specific content of the polymer. Experimental values are then used to calculate intercepts and slopes of the equations by linear regression. From the estimated values of such parameters the in vivo values of several variables of interest can be calculated. These include in vivo density and volume of the glycogen inclusion, as well as density and volume of the structural material in the cell. The results are consistent with the glycogen inclusions being hydrated.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1574-6968.1989.tb03305.x

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8

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Comparison of pure cultures and natural assemblages of planktonic photosynthetic sulfur bacteria by low molecular mass RNA fingerprinting (2000)

Casamayor, Emilio O. ; Núñez-Cardona, M.T. ; Calderón-Paz, J.Isidro ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

FEMS microbiology ecology 32 (2000), S. 0

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ISSN: 1574-6941

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Pure cultures of phototrophic sulfur bacteria were compared to natural populations that bloom in karstic lakes by electrophoretic analysis of low molecular mass RNA molecules (lmwRNA) and microscopy. Similarities between dominant community members, field isolates and reference strains were established by comparing the lmwRNA band patterns through dendrograms produced with Euclidean distances and the average linkage clustering method, by a single, quick, one-step method. The fingerprinting analysis had three objectives: (i) to compare microbial assemblages from different geographical locations, (ii) to compare those organisms which grow in pure culture to those forming planktonic blooms and (iii) to give a preliminary view of the identity of the predominant community members. The lmwRNA analysis yielded a number of clusters consistent with the microscopic observations and allowed rapid comparison of the microbial communities without the need to isolate their individual components. The fingerprints of natural communities were different from most of the laboratory strains tested. Purple sulfur bacteria responsible for the blooms analyzed in karstic lakes were more closely related to the Thiocystis group than to the classical strains extensively studied in the laboratory.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1574-6941.2000.tb00695.x

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9

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Molecular characterization of cDNAs corresponding to genes expressed during almond (Prunus amygdalus Batsch) seed development (1995)

Garcia-Mas, Jordi ; Messeguer, Ramon ; Arús, Pere ; [et al.]

Springer

Plant molecular biology 27 (1995), S. 205-210

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ISSN: 1573-5028

Keywords: almond ; cDNA sequence ; prunin ; oleosin

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract A number of different cDNA clones corresponding to the most abundant mRNAs present in immature seeds have been isolated from an almond (Prunus amygdalus cv. Texas) immature seed cDNA library. Those corresponding to proteins involved in storage processes have been further characterized. Two of these cDNAs (PA3BF1 and PA3BE12) code for the almond globulins (prunins), the main family of storage proteins synthesized in seeds during embryogenesis, and another cDNA (PA3BA1) codes for the 15.7 kDa almond oleosin, a protein located on the surface of oil bodies in plant seeds. These cDNAs have been sequenced and their expression during almond fruit development has been studied. Their expression is seed-specific and localized in cotyledons around 100 days after flowering. Both prunin and oleosin genes are present in one or two copies in the almond genome.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00019192

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