- Volume 133, Issue 4, 1987
Volume 133, Issue 4, 1987
- Physiology And Growth
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Changes in 45Ca and 109Cd Uptake, Membrane Potential and Cell pH in Saccharomyces cerevisiae Provoked by Cd2+
More LessSUMMARY: The effect of Cd2+ poisoning of Saccharomyces cerevisiae on 45Ca, 109Cd and [14C]tetraphenyl phosphonium (TPP) uptake and cell pH was examined. At Cd2+ concentrations that produced substantial K+ efflux the rates of uptake of 45Ca, 109Cd and [14C]TPP increased progressively during incubation of the cells with Cd2+, and the cell pH was lowered concomitantly. The initial rates of uptake of the divalent cations and of TPP were increased in cells pre-loaded with Cd2+, which shows that stimulation of the ion fluxes was exerted by the Cd2+ that accumulated in the cells. The distribution ratio of TPP between cells and medium, however, was decreased by Cd2+. Although hyperpolarization of the cell membrane by Cd2+ cannot be excluded, it is argued that Cd2+ primarily stimulated divalent cation uptake by increasing the cation permeability of the cell membrane allowing the cations to enter the cells more easily.
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Transport, Nutritional and Metabolic Studies of Taurine in Staphylococci
More LessSUMMARY: A specific, Na+-dependent, energy-requiring transport system for taurine has been reported recently in the Staphylococcus aureus M strain. Taurine was taken up vigorously by all S. aureus strains tested. The system was Na+-dependent, and Na+-decreased the Km but had no effect on the V max of the transport system. Among coagulase-negative staphylococci, the Staphylococcus epidermidis group (a taxonomically related group of species associated with humans or other primates) and the free-living, wide-ranging species Staphylococcus sciuri showed vigorous taurine uptake. Somewhat lower rates were found in the Staphylococcus saprophyticus group. Low or barely detectable uptake rates were noted in other staphylococcal species that were primarily of animal origin. No taurine uptake was detected in a variety of other bacterial species tested. Taurine uptake, which was not Na+-dependent, occurred in a Pseudomonas aeruginosa strain grown on taurine as sole energy, carbon, nitrogen, and sulphur source, but not when it was grown in a gluconate/salts medium. In nutritional studies we were unable to demonstrate a role for taurine as a sulphur source for S. aureus. [1,2-14C]- and [35S]taurine were taken up during overnight growth of cells, and radioactivity was distributed similarly among cellular fractions, indicating that the carbon and sulphur atoms of taurine were not cleaved and had the same fate. We were unable to demonstrate any catabolism of taurine in radiorespirometric experiments to detect evolution of 14CO2 by cells incubated with [1,2-14C]taurine. Thus, we found no evidence for a role of taurine in the energy, carbon and sulphur metabolism of S. aureus.
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Effect of Ethanol on Activity of the Plasma-membrane ATPase in, and Accumulation of Glycine by, Saccharomyces Cerevisiae
More LessSUMMARY: The pH optimum of the ATPase activity in plasma membranes from Saccharomyces cerevisiae NCYC 431 from 8 h cultures was around 65 and that in membranes from organisms from 16 h cultures near 6·0. The K m[ATP] of the enzyme was virtually unaffected by the age of the culture from which organisms were harvested, although the V max of the enzyme in membranes from organisms from 8 h cultures was higher than that for organisms from 16 h cultures. Ethanol noncompetitively inhibited ATPase activity in membranes, although the inhibition constant for the enzyme from organisms from 8 h cultures was lower than that from organisms from 16 h cultures. Glycine accumulation by the general amino acid permease was non-competitively inhibited by ethanol. Inhibition constants were virtually the same for glycine uptake by deenergized organisms from 8 h and 16 h cultures, but under energized conditions the value was greater for organisms from 16 h rather than 8 h cultures. The data indicate that inhibition of plasma-membrane ATPase activity by ethanol could account, at least in part, for inhibition of glycine accumulation by ethanol.
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PQQ-Dependent Production of Gluconic Acid by Acinetobacter, Agrobacterium and Rhizobium Species
More LessSUMMARY: Acinetobacter Iwoffi, Azotobacter vinelandii, Agrobacterium and Rhizobium species contain quinoprotein glucose dehydrogenase apoenzyme (EC 1.1.99.17). Addition to whole cells of pyrrolo-quinoline quinone (PQQ), the prosthetic group of this enzyme, resulted in the production of gluconic acid from glucose. The in vivo reconstitution of apo-glucose dehydrogenase with PQQ was dependent on the presence of Ca2+ or Mg2+. Optimal conditions for reconstitution allowed maximal glucose dehydrogenase activity in the presence of 1–10 nmol PQQ 1−1. Synthesis of the apoenzyme of glucose dehydrogenase was not dependent on glucose in the growth media. The physiological significance of the synthesis of apo-glucose dehydrogenase, as found in a variety of bacteria, is discussed.
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Effects of CO2 on Budding and Fission Yeasts
More LessSUMMARY: The budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe were grown under CO2 pressure. Cell division was inhibited in both yeasts; RNA and protein content per cell declined but DNA continued to be synthesized and, in the case of Sacch. cerevisiae, reached twice the normal level within 24 h. Changes in mean cell volume occurred in both yeasts within 1 h; an increase occurred in the budding yeast while a decrease was observed in the fission yeast. The results suggest that CO2 may exert its influence on cell characteristics through a change in cell volume.
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The Effect of Nocodazole on Cell Cycle Events in the Plasmodial Slime Mould Physarum Polycephalum
More LessThe action of nocodazole on nuclear morphology, DNA replication and thymidine (TdR) kinase activity has been examined in growing and starving plasmodia of the CL strain of Physarum polycephalum. In the growing plasmodium, nocodazole treatment more than 2 h before mitosis began prevented both mitosis and DNA replication from occurring at the normal time and also prevented the increase in TdR kinase specific activity normally associated with the onset of mitosis. Nocodazole treatment less than 2 h before mitosis began allowed the process to begin at the normal time, but it was not completed. A normal increase in TdR kinase specific activity accompanied the abortive mitosis, but only limited DNA replication was detected. A similar effect of nocodazole on the occurrence of DNA synthesis in starving plasmodia was found. Nocodazole treatment of a starved plasmodium re-fed with growth medium indicated that the plasmodium was in the G2 phase of the cell cycle when it became competent to sporulate.
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Relationship Between Cellulolytic Activity and Adhesion to Cellulose in Ruminococcus Albus
More LessSUMMARY: Bacterial adhesion to cellulose was measured for 13 cellulolytic and 10 non-cellulolytic, xylan-utilizing strains of the ruminal bacterium Ruminococcus albus. Radiolabelled bacteria adhering to Whatman CF11 cellulose powder were determined. Adhesion of the cellulolytic strains ranged from 0 to 49% of the added bacteria. Of the non-cellulolytic strains, 9 showed < 1% adhesion, while one strain gave 5% adhesion. For the cellulolytic strains filter paper solubilization ranged from 24 to 100%, while solubilization of CF11 cellulose varied from 0 to 20%. Both cellulolytic and non-cellulolytic strains produced carboxymethylcellulase (CMCase) activity. SDS-PAGE of cell extracts followed by incubation with a gel overlay containing CMC or xylan produced a zymogram of hydrolytic enzyme activity. The cellulolytic strains showed a number of bands of CMCase and xylanase activity. Non-cellulolytic strains possessed fewer bands of activity towards both CMC and xylan. Certain of the enzymes appeared to possess both CMCase and xylanase activity. Bacterial cell surface hydrophobicity was also measured, but no correlation was found between hydrophobicity and adhesion to cellulose.
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Determination of Growth Parameters of Methylamine-using Bacteria
More LessGrowth parameters on methylamine and glucose were determined for obligately methylotrophic bacterium B6/2, facultatively methylotrophic bacterium DT26 and Pseudomonas NB4, which is able to use methylamine as sole nitrogen source but not as sole carbon and energy source. substrate saturation constants were determined by a respirometric method. Values obtained for maximum specific growth rates (h−1), substrate saturation constants (μmol 1−1), yield coefficient as 50 % maximum growth rate [(g dry biomass) mol−1] and maintenance coefficient [mmol (g dry biomass)−1 h−1], respectively, were 0·33, 36, 21·2 and 3·2 for B6/2 with methylamine as sole carbon, energy and nitrogen source, 0·09, 5·1, 15·6 and 1·8 for DT26 with methylamine as sole carbon, energy and nitrogen source, 0·20, 2·5, 94 and 0·70 for DT26 with glucose as sole carbon and energy source and NH+ 4 as sole nitrogen source, and 0·58, 6·1, 67 and 0·63 for NB4 with glucose as sole carbon and energy source and NH+ 4 as sole nitrogen source. Pseudomonas NB4 grew with a maximum specific growth rate of 0·35 with glucose as sole carbon and energy source and methylamine as sole nitrogen source.
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Control of the Mating Competence Rhythm in Chlamydomonas eugametos
More LessGametes of Chlamydomonas eugametos lose their mating competence during the light periods of a 24 h light/dark (LD) cycle, and reacquire it in the dark periods. A diurnal rhythm in sexual agglutinability of the flagella underlies these fluctuations. Under constant environmental conditions the oscillation persists as an endogenous circadian rhythm. Under natural environmental conditions the rhythm is cooperatively driven by endogenous and exogenous signals. Exogenous control includes a decline in agglutinability upon illumination, which can be countered by Diuron, and a rise in agglutinability upon lowering of the temperature. In LD, pronounced fluctuations of the external pH are found that can be blocked by Diuron. The pH rhythm does not interfere with the agglutinability rhythm. The control of other rhythms in Chlamydomonas is discussed. As sexual agglutinability is due to well-characterized agglutinins located on the flagellar membrane, this biological rhythm lends itself to further exploration at the molecular level.
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- Systematics
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Investigation of Variation in Phenotype and DNA Content between Single-conidium Isolates of Single Penicillium Strains
More LessSUMMARY: Variation in phenotypic properties was examined in three strains of closely related fasciculate species of Penicillium using 114 morphological, physiological, and biochemical characters. Thirty-six of these characters showed variation within single-conidium isolates of the same strain. Conidial sizes and nuclear DNA contents were compared using flow microfluorimetry; these results suggested that significant differences in conidial DNA content are associated with phenotypic variation. The taxonomic significance of the results is discussed.
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Differentiation of Shigella by Esterase Electrophoretic Polymorphism
Ph. Goullet and B. PicardSUMMARY: The electrophoretic mobilities of four esterases (A, B, C and I) of 182 strains of Shigella dysenteriae, S. flexneri, S. boydii and S. sonnei were compared to those of 636 strains of Escherichia coli from various origins, including the Alkalescens Dispar group and entero-invasive strains. Discriminant analysis of the distribution of esterases among the strains revealed that Shigella could be distinguished from E. coli by differences in the distribution of allozymes of esterases C and I. Principal components analysis distinguished four major clusters of Shigella strains corresponding to the following: S. dysenteriae serotype 1; S. flexneri serotypes 1 to 5; S. flexneri serotype 6 and S. boydii serotypes 2 and 4; and S. sonnei. The last three were characterized by distinct electrophoretic variants of carboxylesterase B, as judged by the two-dimensional electrophoretic profile and titration curves. The distinct esterase pattern obtained for the strains of S. boydii serotype 13 substantiates the view that this serotype may constitute a new species.
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Long-chain Fatty Acid Compositions of Some Asporogenous Yeasts and Their Respective Ascosporogenous States
More LessSUMMARY: Long-chain fatty acid compositions were determined for strains of seven species of Candida and their counterparts within the perfect genera: Candida shehatae and Pichia stipitis, Candida kefyr and Kluyveromyces marxianus, Candida lipolytica and Yarrowia lipolytica, Candida pelliculosa and Hansenula anomala, Candida pseudotropicalis and Kluyveromyces fragilis, Candida utilis and Hansenula jadinii, Candida parapsilosis and Lodderomyces elongisporus, Candida shehatae and Pichia stipitis. Close correlations were found between the fatty acid compositions of these pairs of strains, indicating that the analysis of long-chain fatty acids may be useful for studying the relationships between the perfect and imperfect states of the genus Candida.
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- Corrigendum
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