Showing papers in "Archives of Microbiology in 1982"

Methanothrix soehngenii gen. nov. sp. nov., a new acetotrophic non-hydrogen-oxidizing methane bacterium

Abstract: A new genus of methanogenic bacteria is described, which was isolated from a mesophilic sewage digester. It is most probably the filamentous bacterium, earlier referred to asMethanobacterium soehngenii, “fat rod” or “acetate organism”. The single non-motile, non-sporeforming cells are rod-shaped (0.8×2 μm) and are normally combined end to end in long filaments, surrounded by a sheath-like structure. The filaments form characteristic bundles.Methanothrix soehngenii decarboxylates acetate, yielding methane and carbon dioxide. Other methanogenic substrates (H2−CO2, formate, methanol, methylamines) are not used for growth or methane formation. Formate is split into hydrogen and carbon dioxide. The temperature optimum for growth and methane formation is 37°C and the optimal pH range is 7.4–7.8. Sulfide and ammonia serve as sulfur and nitrogen source respectively. Oxygen completely inhibits growth and methane formation, but the bacteria do not loose their viability when exposed to high oxygen concentrations. 100 mg/l vancomycin showed no inhibition of growth and methanogenesis. No growth and methane formation was observed in the presence of: 2-bromoethanesulfonic acid, viologen dyes, chloroform, and KCN. The bacterium has a growth yield on acetate of 1.1–1.4 g biomass per mol acetate. The apparent “K S ” of the acetate conversion system to methane and carbon dioxide is 0.7 mmol/l. The DNA base composition is 51.9 mol% guanine plus cytosine. The nameMethanothrix is proposed for this new genus of filamentous methane bacterium. The type species,Methanothrix soehngenii sp. nov., is named in honor of N. L. Sohngen.

Different Ks values for hydrogen of methanogenic bacteria and sulfate reducing bacteria: An explanation for the apparent inhibition of methanogenesis by sulfate

Abstract: Desulfovibrio vulgaris (Marburg) and Methanobrevibacter arboriphilus (AZ) are anaerobic sewage sludge bacteria which grow on H2 plus sulfate and H2 plus CO2 as sole energy sources, respectively. Their apparent Ks values for H2 were determined and found to be approximately 1 μM for the sulfate reducing bacterium and 6 μM for the methanogenic bacterium. In mixed cell suspensions of the two bacteria (adjusted to equal Vmax) the rate of H2 consumption by D. vulgaris was five times that of M. arboriphilus, when the hydrogen supply was rate limiting. The apparent inhibition of methanogenesis was of the same order as expected from the different Ks values for H2. Difference in substrate affinities can thus account for the inhibition of methanogenesis from H2 and CO2 in sulfate rich environments, where the H2 concentration is well below 5 μM.

Maintenance energy: a general model for energy-limited and energy-sufficient growth.

Abstract: The new model proposed to account for the energy requirement for growth includes both a constant maintenance energy term (m) independent of the specific growth rate and a term (m') which decreases linearly with increase in specific growth rate and becomes zero at the maximum specific growth rate. The available data for testing the model do not deviate significantly from the relations predicted. Consistent values of the maximum growth yield (YG) can be derived, irrespective of whether the cultures are energy limited or energy sufficient. Attention is drawn to the possibility that the constant maintenance energy term may be estimated from the maximum specific growth rate.

Kinetic mechanism for the ability of sulfate reducers to out-compete methanogens for acetate

Abstract: Methanosarcina barkeri and Desulfobacter postgatei are ubiquitous anaerobic bacteria which grow on acetate or acetate plus sulfate, respectively, as sole energy sources. Their apparent K s values for acetate were determined and found to be approximately 0.2 mM for the sulfate-reducing bacterium and 3 mM for the methanogenic bacterium. In mixed cell suspensions of the two bacteria (adjusted to equal V max) the rate of acetate consumption by D. postgatei approached 15-fold the rate of M. barkeri at low acetate concentrations. The apparent inhibition of methanogenesis was of the same order as expected from the different K s value for acetate. Difference in substrate affinities can thus account for the inhibition of methanogenesis from acetate in sulfate-rich environments, where the acetate concentration is well below 1 mM.

Studies on dissimilatory sulfate-reducing bacteria that decompose fatty acids II. Incomplete oxidation of propionate by Desulfobulbus propionicus gen. nov., sp. nov.

Abstract: A new type of sulfate-reducing bacteria with ellipsoidal to lemon-shaped cells was regularly enriched from anaerobic freshwater and marine mud samples when mineral media with propionate and sulfate were used. Three strains (1pr3, 2pr4, 3pr10) were isolated in pure culture. Propionate, lactate and alcohols were used as electron donors and carbon sources. Growth on H2 required acetate as a carbon source in the presence of CO2. Stoichiometric measurements revealed that oxidation of propionate was incomplete and led to acetate as an endproduct. Instead of sulfate, strain 1pr3 was shown to reduce sulfite and thiosulfate to H2S; nitrate also served as electron acceptor and was reduced to ammonia. With lactate or pyruvate, all three strains were able to grow without external electron acceptor and formed propionate and acetate as fermentation products. None of the strains contained desulfoviridin. In strain 1pr3 cytochromes of the b- and c-type were identified. Strain 1pr3 is described as type strain of the new species and genus, Desulfobulbus propionicus.

Methanococcus thermolithotrophicus, a novel thermophilic lithotrophic methanogen

Abstract: An autotrophic thermophilic motile coccoid methanogen was isolated from geothermally heated sea sediments close to Naples, Italy. Growth occurs on H2/CO2 and on formate between 30 and 70°C with an optimum at 65°C. The optimal doubling time is only 55 min. The NaCl-concentration ranges from 1.3% to 8.3% with an optimum around 4%. By its G+C-content of 31.3 mol%, its subunit envelope, and by DNA-RNA hybridization the new isolate is clearly defined to be a member of the genusMethanococcus. We name itMethanococcus thermolithotrophicus.

Fermentation of Trihydroxybenzenes by Pelobacter acidigallici gen. nov. sp. nov., a New Strictly Anaerobic, Non-Sporeforming Bacterium

Abstract: Five strains of rod-shaped, Gram-negative, non-sporing, strictly anaerobic bacteria were isolated from limnic and marine mud samples with gallic acid or phloroglucinol as sole substrate. All strains grew in defined mineral media without any growth factors; marine isolates required salt concentrations higher than 1% for growth, two freshwater strains only thrived in freshwater medium. Gallic acid, pyrogallol, 2,4,6-trihydroxybenzoic acid, and phloroglucinol were the only substrates utilized and were fermented stoichiometrically to 3 mol acetate (and 1 mol CO2) per mol with a growth yield of 10g cell dry weight per mol of substrate. Neither sulfate, sulfur, nor nitrate were reduced. The DNA base ratio was 51.8% guanine plus cytosine. A marine isolate, Ma Gal 2, is described as type strain of a new genus and species, Pelobacter acidigallici gen. nov. sp. nov., in the family Bacteroidaceae. In coculture with Acetobacterium woodii, the new isolates converted also syringic acid completely to acetate. Cocultures with Methanosarcina barkeri converted the respective substrates completely to methane and carbon dioxide.

Enumeration of Methanobrevibacter smithii in human feces.

Abstract: A platin medium containing cephalothin and clindamycin was developed for enumeration and isolation of methanogens in human feces. Specimens from nine CH4-producing subjects had total anaerobe counts of 1–8×1011/g dry weight. Methanogen counts on the antibiotic medium ranged from 0.001–12.6% of the total anaerobe count. There was no correlation between age, sex, or percent dry fecal weight and the ratio of methanogens to total counts. Specimens from eight non-CH4-producing individuals contained bacteria thay yielded nonmethanogenic colonies on the antibiotic medium. The means±SD of the logarithm of the total counts per gram dry weight were 11.4±0.29 and 11.38±0.44 for the positive and negative groups respectively. Values for the antibiotic-resistant flora were 8.8±1.13 and 7.78±1.08 respectively. Methanogens were isolated from the most dilute inoculum of each specimen from CH4-producing subjects. All isolates were morphologically, physiologically, and immunologically identical to Methanobrevibacter smithii. Growth of methanogens in media that were essentially extracts of CH4-negative feces suggested that no nutrients were lacking or inhibitors present in intestinal contents that prevent the growth of methanogens in these individuals.

Salient Biochemical Characters of Actinobacillus actinomycetemcomitans

Abstract: A total of 136 strains of Actinobacillus actinomycetemcomitans were studied for 135 features. All isolates were small nonmotile capnophilic gram-negative rods which grew with no requirement of X or V growth factors. They all decomposed hydrogen peroxide, were oxidase-negative and benzidine-positive, reduced nitrate, produced strong alkaline and acid phosphatases, and fermented fructose, glucose and mannose. Variable fermentation results were obtained with dextrin, maltose, mannitol and xylose. Some isolates produced small amounts of gas. Representative strains of Haemophilus aphrophilus were morphologically and biochemically quite similar to A. actinomycetemcomitans. Characters which should prove to be useful to identify and distinguish these two species include catalase reaction. fermentation of lactose, starch, sucrose and trehalose, and resistance to sodium fluoride. This information allows a rapid diagnosis by species and may be helpful in studies of infections involving these organisms.

Alcohol conversions by desulfobulbus-propionicus lindhorst in the presence and absence of sulfate and hydrogen

Abstract: Ethanol was rapidly degraded to mainly acetate in anaerobic freshwater sediment slurries. Propionate was produced in small amounts. Desulfovibrio species were the dominant bacteria among the ethanol-degrading organisms. The propionate-producing Desulfobulbus propionicus came to the fore under iron-limited conditions in an ethanol-limited chemostat with excess sulfate inoculated with anaerobic intertidal freshwater sediment. In the absence of sulfate, ethanol was fermented by D. propionicus Lindhorst to propionate and acetate in a molar ratio of 2.0.l-Propanol was intermediately produced during the fermentation of ethanol. In the presence of H2 and CO2, ethanol was quantitatively converted to propionate. H2-plus sulfate-grown cells of D. propionicus Lindhorst were able to oxidize l-propanol and l-butanol to propionate and butyrate respectively with the concomitant reduction of acetate plus CO2 to propionate. Growth was also observed on acetate alone in the presence of H2 and CO2 D. propionicus was able to grow mixotrophically on H2 plus an organic compound. Finally, a brief discussion has been given of the ecological niche of D. propionicus in anaerobic freshwater sediments.

Genomic and physiological diversity amongst strains of Thiobacillus ferrooxidans, and genomic comparison with Thiobacillus thiooxidans

Abstract: Twenty-three strains of Thiobacillus ferrooxidans of known pedigree were examined. Thirteen strains survived 65° C for 5 min and 7 of these for 10 min, but sporulation was never observed. All strains grew between 25° C and 35° C and some strains grew at 5° and 40° C. They were genomically diverse, comprising 7 DNA homology groups, and the GC content varied from 55–65 mol %. Correlation between genomic group and growth temperature was noted. All strains grew on ferrous sulfate as energy source, but some failed to utilize elemental sulfur. Acidified thiosulfate supported growth of most of the strains examined but it was judged to be a poor substrate upon which to base taxonomic conclusions because of decomposition of thiosulfate in acid. Six strains of Thiobacillus thiooxidans showed negligible genomic affinity to T. ferrooxidans, and they comprised 2 DNA homology groups and their GC content varied from 52–62 mol%. Anomalies due to contaminants in cultures of T. ferrooxidans were resolved, and the contaminants were identified.

Isolation and characterization of an anaerobic syntrophic benzoate degrading bacterium from sewage sludge

Abstract: An anaerobic, motile, gram-negative, rod-shaped bacterium is described which degrades benzoate in coculture with an H2-utilizing organism and in the absence of exogenous electron acceptors such as O2, SO 4 = or NO 3 - . The bacterium was isolated from a municipal primary, anaerobic sewage digestor using anaerobic roll-tube medium with benzoate as the main energy source and in syntrophic association with an H2-utilizing sulfate-reducing Desulfovibrio sp. which cannot utilize benzoate or fatty acids apart from formate as energy source. The benzoate utilizer produced acetate (3 mol/mol of substrate degraded) and presumably CO2 and H2, or formate from benzoate. In media without sulfate and with Methanospirillum hungatei (a methanogen that utilizes only H2−CO2 or formate as the energy source) added, 3 mol of acetate and 0.7 mol of methane were produced per mol of benzoate and CO2 was probably formed. Low numbers of Desulfovibrio sp. were present in the methanogenic coculture and a pure coculture of the benzoate utilizer with M. hungatei was not obtained. The generation times for growth of the sulfate-reducing and methanogenic cocultures were 132 and 166h, respectively. The benzoate utilizer did not utilize other common aromatic compounds, C 3 - −C7 monocarboxylic acids, or C4-C6 dicarboxylic acids for growth, nor did it appear to use SO 4 = , NO 3 - or fumarate as alternative electron acceptors. Addition of H2 inhibited growth and benzoate degradation.

beta-Glucosidase excretion by Trichoderma pseudokoningii: correlation with cell wall bound beta-1.3-glucanase activities.

Abstract: The formation and excretion of beta-glucosidase from Trichoderma pseudokoningii was studied during growth on different carbon sources. The enzyme was present under all conditions examined, but increased activity was found during growth on carbon sources favouring slow growth. Two different patterns of beta-glucosidase excretion were observed: on carbon sources allowing fast growth a relatively high percentage of total activity was found in the culture fluid, which decreases as the culture grows older, but which increases again during the phase of cell lysis; on carbon sources favouring slow growth, excretion is initially low, but commences at later culture stages. Changes in cell wall composition and cell wall lytic enzyme activities associated with the cell walls were examined during phases of high and low ratios of extracellular to cell-wall bound beta-glucosidase activities. With no component of the cell wall (chitin, alpha-glucan, beta-glucan, galactosamine) could correlation with beta-glucosidase excretion be identified. Among a number of cell-wall lytic, cell-wall associated enzymes (alpha-glucanases, beta-glucanases, glucosaminidase, galactosaminidase), beta-1.3-glucanase activity correlated well with the excretion of beta-glucosidase. The results suggest a possible role of beta-1.3-glucanases in the mechanism of release of beta-glucosidase from cell walls of T. pseudokoningii; this is discussed.

Lipids in the classification of Nocardioides: Reclassification of Arthrobacter simplex (Jensen) lochhead in the genus Nocardioides (Prauser) emend. O'Donnell et al. as Nocardioides simplex comb. nov.

Abstract: Representative strains of Nocardioides, Arthrobacter simplex and Arthrobacter tumescens were degraded by acid methanolysis and the fatty acid esters released examined by thin-layer and gas chromatography. Branchedchain 14-methylpentadecanoic acid (iso-16) was the predominant component in all but one of the Nocardioides strains. Arthrobacter simplex also contained major amounts of this acid whereas A. tumescens had only minor amounts. All of the test strains possessed 15 and 17 carbon straight chain acids, tuberculostearic acid (10-methyloctadecanoic acid) and its 17 and 18-carbon homologues. The fatty acid profiles of Nocardioides strains lacked 13-methyltetradecanoic and heptadecanoic acids which were both present in Arthrobacter simplex and Arthrobacter tumescens. The profiles of these latter organisms were quantitatively different from each other. The polar lipids of the test strains all contained diphosphatidylglycerol and phosphatidylglycerol but only Arthrobacter tumescens contained phosphatidylinositol and three unidentified polar lipids. Nocardioides and Arthrobacter simplex strains all contained two very characteristic closely related polar lipids.

Hydrophobic and electrostatic characterization of surface structures of bacteria and its relationship to adhesion to an air-water interface

Abstract: Hydrophobic and charge-charge interactions of Salmonella typhimirium and Serratia marcescens were determined and related to their content of fimbriae and lipopolysaccharide (LPS). The cell surface structures were characterized with hydrophobic interaction chromatography (HIC), electrostatic interaction chromatography (ESIC) and particle electrophoresis measurements. The degree of interaction at the air-water interface was tested using a monolayered lipid film applied to an aqueous surface. The cell surface hydrophobicity of S. typhimurium in the presence of fimbriae was less in smooth than in rought bacteria. Examination of a series of rough mutants of S. typhimurium indicates that reduction of the O-side chain and core oligosaccharides was correlated with increased cell hydrophobicity. The enrichment factors at the air-water interface were significantly higher for fimbriated than for non-fimbriated S. typhimurium cells. Fimbriated S. marcescens cells were less hydrophobic and adhered to a lesser degree at the air-water surface than non-fimbriated counterparts. Electrophoretic measurements and adsorption to ion exchangers gives different information about the surface charge of bacteria. The latter technique gives the interaction between localized charged surfaces.

Comparative studies onChlorella cell walls: Induction of protoplast formation

Abstract: Among 12 strains ofChlorella ellipsoidea, C. vulgaris, andC. saccharophila tested, 4 strains (1,C. ellpsoidea; 2,C. vulgaris; 1,C. saccharophila) formed osmotically labile protoplasts after treatment with mixtures of polysaccharide degrading enzymes. The relationship between enzymatical digestibility and structure or composition ofChlorella cell walls were studied by electron microscopy and staining techniques with some specific dyes. The cell wall structures of the 12Chlorella strains were grouped into three types: (1) with a trilaminar outer layer, (2) with a thin outer monolayer, and (3) without an outer layer. Protoplasts were formed only from the strains with a cell wall of Type 2. In the strains with a cell wall of Type 1, the outer layer protected the inner major microfibrillar layer against enzymatic digestion. The cell wall of Type 3 was totally resistant to the enzymes; the chemical composition of the cell wall would be somewhat different from that of other types.

Propionigenium modestum gen. nov. sp. nov. a new strictly anaerobic, nonsporing bacterium growing on succinate

Abstract: From marine and freshwater mud samples and from human saliva new strictly anaerobic, Gram-negative, nonsporeforming bacteria were isolated growing with succinate as sole source of carbon and energy. All strains grew in defined mineral media containing at least 1% sodium chloride. Succinate was stoichiometrically transformed to propionate und carbon dioxide; the growth yield varied between 2.1 and 2.4 g cell dry weight per mol of succinate fermented. In addition to succinate, only fumarate, l-aspartate, l-malate, oxaloacetate and pyruvate, were utilized and were stoichiometrically fermented to propionate and acetate. Yeast extract was not fermented but enhanced growth rates and yields. Neither sulfate, sulfur, nor nitrate were reduced. The DNA base ratio was 33.9±0.3 mol % guanine plus cytosine. A marine isolate, strain Gra Succ 2, is described as type strain of a new species, Propionigenium modestum gen. nov. sp. nov., in the family Bacteroidaceae.

Fermentative metabolism of substituted monoaromatic compounds by a bacterial community from anaerobic sediments

Abstract: An anaerobic microbial community containing 4 to 5 different populations capable of degrading syringic acid completely to CH4 and CO2 was enriched from freshwater lake sediments. The community can be maintained with syringic acid as sole carbon- and energy source in a defined mineral medium. Syringic acid is converted stoichiometrically according to $$C_9 H_{10} O_5 + 4H_2 O \to 4{\raise0.5ex\hbox{$\scriptstyle 1$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 2$}}CH_3 COOH \to 4{\raise0.5ex\hbox{$\scriptstyle 1$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 2$}}CH_4 + 4{\raise0.5ex\hbox{$\scriptstyle 1$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 2$}}CO_2$$ . The aromatic ring of several other syringols can be degraded as well. The presence of 3 hydroxy or methoxy substituents seems to be the only condition for successful ring cleavage. Corresponding catechols and guaiacols, however, are converted to 2-hydroxyphenol (catechol); the ring is not cleaved. Methoxylated syringols are first converted to the corresponding hydroxylated analogs with concomittant formation of CH4 and CO2 from the methoxyl carbon. A second population ferments gallic acid and pyrogallol stoichiometrically to 3 mol acetate. Methane formation from acetate is attributed to several methanogens, none of which can be associated with any one of the known acetotrophic ones.

Effect of organic matter on growth and cell yield of ammonia-oxidizing bacteria

Abstract: The effect of various organic compounds on the growth of ammonia-oxidizing bacteria was examined.Nitrosococcus oceanus, a strongly halophilic bacterium, had a very low tolerance to organic matter compared with other organisms tested. Organic compounds scarcely affected the growth of theNitrosomonas strains whereas nitrite formation by bothNitrosococcus mobilis strains was inhibited by nearly all of the substances tested. The growth ofNitrosospira strain Nsp1 was enhanced more than 30% by acetate and formate, but not growth was detectable in the presence of pyruvate. On the contrary,Nitrosospira strain Nsp5 was stimulated only by pyruvate. Nitrite formation by the twoNitrosovibrio tenuis strains tested was similar. The growth of both strains was enhanced considerably by formate and glucose; acetate and, to a greater extent, pyruvate inhibited these bacteria. In batch culture, the energy efficiency of autotrophically grown ammonia-oxidizing bacteria varied from strain to strain. The cell yield of mixotrophically grown cultures, per unit of ammonia oxidized, was increased in comparison with autotrophic ones. No heterotrophic growth was detected.

Methanoplanus limicola , a plate-shaped methanogen representing a novel family, the methanoplanaceae

Abstract: An angular plate-shaped weakly motile mesophilic methanogen was isolated from a swamp of drilling waste in Italy. Growth occurs on H2/CO2 or on formate. Acetate is required in addition. The optimal doubling time is 7 h at 40° C. The cell envelope is composed most likely of glycoprotein subunits in hexagonal arrangement. The GC-content of its DNA is 47.5 mol%. On the basis of DNA-RNA hybridization it was found to represent a new family, the Methanoplanaceae within the order Methanomicrobiales.

Osmoregulation and cell composition in salt-adaptation of Nostoc muscorum

Abstract: Adaptation to salt in the cyanobacterium Nostocmuscorum, is composed of a few mechanisms which together lead to the generation of a salt-tolerant cell. The initial mechanism combines a stimulation of photosynthetic activity with the accumulation of sucrose as an osmoregulator. The secondary mechanism involves the adaptation of N2 fixation activity and protein biosynthesis. The adaptation is most efficient in response to NaCl-induced stress and functions only partially under stress induced by either KCl or a nonionic osmoticum such as mannitol.

Bacterial scavenging: Utilization of fatty acids localized at a solid-liquid interface

Abstract: A model oligotrophic aquatic system involving localization of fatty acids on a solid surface was used to quantitate scavenging by three bacteria; Leptospira biflexa patoc 1 which adheres reversibly, pigmented Serratia marcescens EF190 which adheres irreversibly, and a non-pigmented hydrophilic mutant of EF190. The Leptospira and pigmented Serratia displayed two distinct scavenging strategies which are related to their different methods of adhesion. The Leptospira efficiently scavenged [1-14C] stearic acid from the surface in 24 h, whereas the pigmented hydrophobic Serratia initially showed a faster rate of removal but the overall rate was considerably slower than that of the Leptospira. The hydrophilic, non-pigmented Serratia required 50h incubation to remove significant amounts of the labelled fatty acid. The greater scavenging ability of the hydrophobic pigmented Serratia strain compared to the hydrophilic non-pigmented mutant could not be attributed to differences in viability of fatty acid metabolism. The hydrophobicity of the pigmented Serratia allows for firmer adhesion and greater interaction with the surface localized nutrients.

Glycogen in thermoacidophilic archaebacteria of the genera Sulfolobus, Thermoproteus, Desulfurococcus and Thermococcus

Abstract: Glycogen has been found in thermoacidophilic archaebacteria of the genera Sulfolobus, Thermoproteus, Desulfurococcus and Thermococcus. Thermoplasma acidophilum yielded a related, though less defined compound. Glycogen was identified by elementary analysis, infrared spectroscopy, the nature of the hydrolysis products, the iodine reaction, and the nature of the products of periodate oxydation and reduction. The average chain length was 7. From crude extracts of Sulfolobus and Thermoproteus complexes of glycogen with 4 respectively 2 proteins have been isolated by CsCl density gradient centrifugation. In either case, one of the proteins was identified as glucosyl transferase. The glucosyl transferase of Sulfolobus acidocaldarius strain B 12 utilizes UDP-glucose as well as ADP-glucose as substrates, with K m values of 0.42 and 0.2 mM respectively and turnover numbers of 4.6 and 5.2 per second respectively. In electron micrographs the isolated glycogen protein complex appears as scale like aggregates, whereas in cell sections amorphous bodies fill large portions of the cells.

Evidence for a membrane bound NADH-plastoquinone-oxidoreductase in Chlamydomonas reinhardii CW-15

Abstract: NADH-plastoquinone-oxidoreductase bound to the membrane fraction of Chlamydomonas reinhardii CW-15 has been solubilized with triton X-100. By treatment with high concentrations of MgCl2 and KCl and (NH4)2SO4 fractionation the enzyme could be enriched 8–10-fold. Spectral properties indicated a flavoprotein probably containing Fe−S groups. The enzyme oxidizes NADH and NADPH with various quinones as electron acceptors. Plastoquinone 1 is an effective electron acceptor, whereas ubiquinone 1 is only reduced with low activity. The enzyme is sensitive to rotenone and thenoyltrifluoroacetone, both inhibitors of ubiquinone reduction by mitochondrial dehydrogenases. As the bound enzyme is sensitive to inhibitors of photosynthetic electron flow, the enzyme is assumed to be responsible for light driven hydrogen evolution at the expense of NADH generating substrates.

Cell wall degradation of Staphylococcus aureus by lysozyme.

Abstract: In contrast to former findings lysozyme was able to attack the cell walls ofStaphylococcus aureus under acid conditions. However, experiments with14C-labelled cell walls and ribonuclease indicated that, under these conditions, lysozyme acted less as an muralytic enzyme but more as an activator of pre-existing autolytic wall enzymes. Electron microscopic studies showed that under these acid conditions the cell walls were degraded by a new mechanism (i.e. “attack from the inside”). This attack on the cell wall started asymmetrically within the region of the cross wall and induced the formation of periodically arranged lytic sites between the cytoplasmic membrane and the cell wall proper. Subsequently, a gap between the cell wall and the cytoplasmic membrane resulted and large cell wall segments became detached and suspended in the medium. The sequence of lytic events corresponded to processes known to take place during wall regeneration and wall formation. In the final stage of lysozyme action at pH 5 no cell debris but “stabilized protoplasts” were to be seen without detectable alterations of the primary shape of the cells. At the same time long extended ribbon-like structures appeared outside the bacteria. The origin as well as the chemical nature of this material is discussed. Furthermore, immunological implications are considered.

Regulatory flexibility of methylotrophic yeasts in chemostat cultures: Simultaneous assimilation of glucose and methanol at a fixed dilution rate

Abstract: The influence of the composition of methanol/glucose-mixtures as only sources of carbon and energy on growth and regulation of the synthesis of enzymes involved in methanol-dissimilation was studied under chemostat conditions at a fixed dilution rate with the methylotrophic yeasts Hansenula polymorpha and Kloeckera sp. 2201. Both carbon sources were found to be utilized completely independently of the composition of the C1/C6 mixture. Using mixtures of 14C-labelled methanol and glucose the growth yield for glucose was found to be constant for all C1/C6-mixtures tested and both yeasts. The growth yield for methanol, however, was reduced by up to 25% when the proportion of methanol in the inflowing medium was lower than 20% (w/w with respect to glucose) for H. polymorpha and 50% (w/w with respect to glucose) for Kloeckera sp. 2201 respectively. During growth with C1/C6-mixtures containing higher C1-proportions of methanol regular growth yields for methanol were recorded which corresponded to the growth yields found with methanol as the only carbon source.

Uranous ion oxidation and carbon dioxide fixation by Thiobacillus ferrooxidans

Abstract: The stoichiometric oxidation of uranous-to uranyl-uranium byThiobacllus ferrooxidans is demonstrated. Fixation of14CO2 and the effect of inhibitors demonstrate that energy is conserved during the oxidation and used for energy-dependent “reverse electron flow” and carbon dioxide fixation.

Nitrite reduction to nitrous oxide by propionibacteria: Detoxication mechanism

Abstract: Characteristics of dissimilatory nitrate reduction by Propionibacterium acidi-propionici, P. freudenreichii, P. jensenii, P. shermanii and P. thoenii were studied. All strains reduced nitrate to nitrite and further to N2O. Recovery of added nitrite-N as N2O-N approached 100%, so that no other end product existed in a significant quantity. Specific rates of N2O production were 3 to 6 orders of magnitude lower than specific rates of N2 production by common denitrifiers. Oxygen but not acetylene inhibited N2O production in P. acidi-propionici and P. thoenii. Nitrite reduction rates were generally higher than nitrate reduction rates. The enzymes involved in nitrate and nitrite reduction were either constitutive or derepressed by anacrobiosis. Nitrate stimulated synthesis of nitrate reductase in P. acidi-propionici. Specific growth rates and growth yields were increased by nitrate. At 10 mM, nitrite was toxic to all strains, and at 1 mM its effect ranged from none to total inhibition. No distinction was obvious between incomplete forms of denitrification and dissimilatory nitrate reduction to ammonia. N2O production from nitrite by propionibacteria may represent a detoxication mechanism rather than a part of an energy transformation system.

Quantitative and structural characteristics of lipids in Chlorobium and Chloroflexus

Abstract: The lipid compositions of Chlorobium limicola (4 strains) and Chloroflexus aurantiacus (2 strains) have been compared. Both species contained straight-chain, saturated and monosaturated fatty acids as their main fatty acid constituents but the patterns were distinctly different. Chlorobium contained acids of chain-length essentally in the range C12−C18 with n-tetradecanoate, hexadecenoate and n-hexadecanoate predominating. Chloroflexus was characterized by the presence of significant amounts of C17 and C18−C20 fatty acids not detected in Chlorobium. The latter, on the other hand, contained hydroxylated and cyclopropane-substituted acids not detected in Chloroflexus. Simple wax esters (C28−C38) were found solely in Chloroflexus and accounted for 2.5–3.0% of the cell dry weight. Their fatty acid constituents ranged from C12−C19 (both saturated and monounsaturated isomers) whereas the alcohols were generally saturated and of chain-length C16−C19. Waxes in the range C34−C36 accounted for more than 60% of the total.

Phosphorus-31 nuclear magnetic resonance studies of intracellular pH, phosphate compartmentation and phosphate transport in yeasts

Abstract: 31P NMR spectra were obtained from suspensions of Candida utilis, Saccharomyces cerevisiae and Zygosaccharomyces bailii grown aerobically on glucose Direct introduction of substrate into the cell suspension, without interruption of the measurements, revealed rapid changes in pH upon addition of the energy source All 31P NMR spectra of the yeasts studied indicated the presence of two major intracellular inorganic phosphate pools at different pH environments The pool at the higher pH was assigned to cytoplasmic phosphate from its response to glucose addition and iodoacetate inhibition of glycolysis After addition of substrate the pH in the compartment containing the second phosphate pool decreased A parallel response was observed for a significant fraction of the terminal and penultimate phosphates of the polyphosphate observed by 31P NMR This suggested that the inorganic phosphate fraction at the lower pH and the polyphosphates originated from the same intracellular compartment, most probably the vacuole In this vacuolar compartment, pH is sensitive to metabolic conditions In the presence of energy source a pH gradient as large as 08 to 15 units could be generated across the vacuolar membrane Under certain conditions net transport of inorganic phosphate across the vacuolar membrane was observed during glycolysis: to the cytoplasm when the cytoplasmic phosphate concentration had become very low due to sugar phosphorylation, and into the vacuole when the former concentration had become high again after glucose exhaustion