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Equol, which produced from daidzein (one of the principal isoflavones), is recognized to be the most resultful in stimulating an estrogenic and antioxidant response. The daidzein transformation was studied during fermentation of five growth media inoculated with feces from a healthy human, and a daidzein conversion strain was isolated. To enrich the bacterial population involved in daidzein metabolism in a complex mixture, fecal samples were treated with antibiotics. The improved propidium monoazide combined with the quantitative polymerase chain reaction (PMAxx-qPCR) assay showed that the ampicillin treatment of samples did result in a reduction of the total visible bacteria counts by 52.2% compared to the treatment without antibiotics. On this basis, the newly isolated rod-shaped, Gram-positive anaerobic bacterium, named strain Y11 (MN560033), was able to metabolize daidzein to equol under anaerobic conditions, with a conversion ratio (equol ratio: the amount of equol produced/amount of supplemented daizein) of 0.56 over 120 h. The 16S rRNA partial sequence of the strain Y11 exhibited 99.8% identity to that of Slackia equolifaciens strain DZE (NR116295). This study will provide new insights into the biotransformation of equol from daidzein by intestinal microbiota from the strain-level and explore the possibility of probiotic interventions., (© The Author(s) 2021. Published by Oxford University Press on behalf of FEMS.)

Gram-positive bacteria assemble a multilayered cell wall that provides tensile strength to the cell. The cell wall is composed of glycan strands cross-linked by nonribosomally synthesized peptide stems. Herein, we modify the peptide stems of the Gram-positive bacterium Bacillus subtilis with noncanonical electrophilic d-amino acids, which when in proximity to adjacent stem peptides form novel covalent 5,3-cross-links. Approximately 20% of canonical cell-wall cross-links can be replaced with synthetic cross-links. While a low level of synthetic cross-link formation does not affect B. subtilis growth and phenotype, at higher levels cell growth is perturbed and bacteria elongate. A comparison of the accumulation of synthetic cross-links over time in Gram-negative and Gram-positive bacteria highlights key differences between them. The ability to perturb cell-wall architecture with synthetic building blocks provides a novel approach to studying the adaptability, elasticity, and porosity of bacterial cell walls., Competing Interests: The authors declare no competing interest.

The latest threat of multidrug-resistant Gram-negative bacteria corresponds to the emergence of carbapenemase NDM-1 (New Delhi metallo-β-lactamase) producers, mostly in Enterobacteriacae. Five bla(NDM) (-1) -positive plasmids of different incompatibility groups (IncL/M, FII, A/C and two untypeable plasmids) from clinical Enterobacteriaceae were evaluated for conjugation properties and host specificity. Successful conjugative transfers were obtained using all tested enterobacterial species as recipients (Escherichia coli, Klebsiella pneumoniae, Salmonella typhimurium and Proteus mirabilis) and all plasmid types. Conjugation frequencies varied from 1 × 10(-4) to 6 × 10(-8) transconjugants per donor. Higher conjugation rates were obtained for two plasmids at 30 °C compared with that observed at 25 and 37 °C. Carbapenems used as selector did not lead to higher conjugation frequencies. None of the five plasmids was transferable to Acinetobacter baumannii or Pseudomonas aeruginosa by conjugation. This work underlines how efficient the spread of the carbapenemase bla(NDM) (-1) gene could be among Enterobacteriaceae., (2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.)

The two-stage process for extreme thermophilic hydrogen and thermophilic methane production from wheat straw hydrolysate was investigated in up-flow anaerobic sludge bed (UASB) reactors. Specific hydrogen and methane yields of 89 ml-H(2)/g-VS (190 ml-H(2)/g-sugars) and 307 ml-CH(4)/g-VS, respectively were achieved simultaneously with the overall VS removal efficiency of 81% by operating with total hydraulic retention time (HRT) of 4 days . The energy conversion efficiency was dramatically increased from only 7.5% in the hydrogen stage to 87.5% of the potential energy from hydrolysate, corresponding to total energy of 13.4 kJ/g-VS. Dominant hydrogen-producing bacteria in the H(2)-UASB reactor were Thermoanaerobacter wiegelii, Caldanaerobacter subteraneus, and Caloramator fervidus. Meanwhile, the CH(4)-UASB reactor was dominated with methanogens of Methanosarcina mazei and Methanothermobacter defluvii. The results from this study suggest the two stage anaerobic process can be effectively used for energy recovery and for stabilization of hydrolysate at anaerobic conditions., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

A Gram-stain-positive, rod-shaped, endospore-forming, halophilic, alkalitolerant bacterium, designated halo-1(T), was isolated from sediment of Xiarinaoer soda lake, located in the Inner Mongolia Autonomous Region of China. Strain halo-1(T) grew in the presence of 9-30 % (w/v) NaCl (optimum 19 %) and at pH 5-10 (optimum pH 9). The cell-wall peptidoglycan contained meso-diaminopimelic acid and the major respiratory isoprenoid quinone was MK-7. The predominant cellular fatty acids of the isolate were anteiso-C(15 : 0) (58.35 %), anteiso-C(17 : 0) (12.89 %) and C(16 : 0) (6.52 %). The polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, glycolipid and a phospholipid of unknown structure. The DNA G+C content of the strain was 46.4 mol%. On the basis of 16S rRNA gene sequence similarity, strain halo-1(T) showed the highest similarity (93.9 %) to Salsuginibacillus kocurii CH9d(T). Strain halo-1(T) could be clearly differentiated from its closest phylogenetic relative on the basis of several phenotypic, genotypic and chemotaxonomic features. Therefore, strain halo-1(T) represents a novel species, for which the name Salsuginibacillus halophilus sp. nov. is proposed, with the type strain halo-1(T) (=CGMCC 1.7653(T) =NBRC 104934(T)).

Antibiotic susceptibility against 19 antimicrobial agents was evaluated in isolates of the genera Lactococcus (46 isolates), Leuconostoc (22), Lactobacillus (19), Staphylococcus (8), Enterococcus (7), and Microccoccus/Kocuria (5) obtained from the predominant microflora of nonrecent and recent types of artisanal raw cow's milk cheeses. Beta-lactams showed broad activity against all genera, although leuconostocs and lactobacilli were highly resistant to oxacillin (80% to 95.5%). Resistance to aminoglycosides was frequent for lactococci and enterococci (particularly for streptomycin), whereas lower rates of resistance were detected for lactobacilli and leuconostocs. Technologically interesting traits for the food industry were distributed among isolates that showed different degrees of resistance to common antibiotics. However, isolates showing resistance to less than 2 antibiotics were mainly those with properties of greatest technological interest (acidifying activity, proteolytic/lipolytic activities, or diacetyl production).

The rate of CO conversion by a pure culture of a thermophilic CO-oxidizing, H2-producing bacterium Carboxydocella sp. strain 1503 was determined by the radioisotopic method. The overall daily uptake of 14CO by the bacterium was estimated at 38-56 micromol CO per 1 ml of the culture. A radioisotopic method was developed to separate and quantitatively determine the products of anaerobic CO conversion by microbial communities in hot springs. The new method was first tested on the microbial community from a sample obtained from a hot spring in Kamchatka. The potential rate of CO conversion by the anaerobic microbial community was found to be 40.75 nmol CO/cm3 sediment per day. 85% of the utilized 14CO was oxidized to carbon dioxide; 14.5% was incorporated into dissolved organic matter, including 0.2% that went into volatile fatty acids; 0.5% was used for cell bio mass production; and only just over 0.001% was converted to methane.

Two anaerobic bacteria involved in the conversion of the plant lignan secoisolariciresinol diglucoside were isolated from faeces of a healthy male adult. The first isolate, strain SDG-Mt85-3Db, was a mesophilic strictly anaerobic Gram-positive helically coiled rod. Based on 16S r RNA gene sequence analysis, its nearest relatives were Clostridium cocleatum (96.7% similarity) and Clostridium ramosum (96.6%). In contrast to these species, the isolate was devoid of alpha-galactosidase and -glucosidase and did not grow on maltose, melibiose, raffinose, rhamnose and trehalose. The hypothesis that strain SDG-Mt85-3Db represents a new bacterial species of the Clostridium cluster XVIII was confirmed by DNA-DNA hybridisation experiments. The G+C content of DNA of strain SDG-Mt85-3Db (30.7+/-0.8 mol%) was comparable with that of Clostridium butyricum, the type species of the genus Clostridium. The name Clostridium saccharogumia is proposed for strain SDG-Mt85-3Db (=DSM 17460T=CCUG 51486T). The second isolate, strain ED-Mt61/PYG-s6, was a mesophilic strictly anaerobic Gram-positive regular rod. Based on 16S rRNA gene sequence analysis, its nearest relatives were Clostridium amygdalinum (93.3%), Clostridium saccharolyticum (93.1%) and Ruminococcus productus (93.0%). The isolate differed from these species in its ability to dehydrogenate enterodiol. It also possessed alpha-arabinosidase and -galactosidase and had a higher G+C content of DNA (48.0 mol%). According to these findings, it is proposed to create a novel genus, Lactonifactor, and a novel species, Lactonifactor longoviformis, to accommodate strain ED-Mt61/PYG-s6. The type strain is DSM 17459T (=CCUG 51487T).

A novel anaerobic, thermophilic, CO-utilizing bacterium, strain KarT, was isolated from a hot spring of Karymskoe Lake, Kamchatka Peninsula. The cells of the novel isolate were Gram-positive, spore-forming, short rods. The bacterium grew chemolithoautotrophically on CO, producing equimolar quantities of H2 and CO2 (according to the equation CO + H2O --> CO2 + H2), and in the absence of CO, under N2 in the gas phase, chemoorganoheterotrophically with yeast extract, sucrose or pyruvate. Growth was observed in the temperature range 50-70 degrees C, with an optimum at 60 degrees C, and in the pH range 6.2-8.0, with an optimum at pH 6.8. The micro-organism did not grow on solid media; it was able to grow only in semi-solid medium containing 0.5 % agar. The generation time under optimal conditions for chemolithoautotrophic growth was 1 h. The G+C content of the DNA was 46.5+/-1 mol%. Growth was completely inhibited by penicillin, novobiocin, streptomycin, kanamycin and neomycin. Analysis of the 16S rRNA gene sequence showed that the isolate should be assigned to the genus Carboxydocella. On the basis of the results of DNA-DNA hybridization and morphological and physiological analyses, strain KarT represents a novel species of the genus Carboxydocella, for which the name Carboxydocella sporoproducens sp. nov. is proposed. The type strain is KarT (=DSM 16521T = VKM B-2358T).

An anaerobic, thermophilic, hydrogen-producing strain T42 was obtained from a hot spring of South Mountain District, Tibet. Cells are Gram-positive, mobile rod-shaped. Spores were not observed. Temperature range for growth is 32 degrees C to 69 degrees C (optimum temperature, 60 degrees C - 62 degrees C), and pH range for growth is 5.0 to 8.8 (optimum pH, 7.0 - 7.5). The generation time is around 30 min. Organic nitrogen sourc is required for growth. Strain T42 utilizes a wide range of carbohydrates, including starch, dextrin, sucrose, cellobiose, fructose, maltose, ribose, glycogen and galactose. Acetate, ethanol, H2 and CO2 are the end products of glucose fermentation. The (G + C) content of strain T42 is 31.2 mol%. Phylogenetic analysis based on the 16S rDNA sequence similarity indicates that strain T42 is the closest relative to Thermobrachium celere and Caloramator indicus. Biological characteristics and phylogenetic analysis of the 16S rDNA gene indicate the new strain belongs to the genus Thermobrachium. Strain T42 produces H2 from glucose at maximal level when growing at 62 degrees C and initial pH 7.2, the hydrogen yields and maximal hydrogen production rate are 1.06 mol H2/mol glucose and 24.0 mmol H2/gDW/h, respectively. Strain T42 also produced H2 by fermentating from a variety of carbohydrates. 20 mmol/L Magnesium and 2 mmol/L iron increase the hydrogen production content by 20% and 23.3%, respectively, but nickel has no effect on the hydrogen production. In the co-culture of strain T42 and methane-producing strain M. thermautotrophicus Z245, hydrogen pressure is dramatically decreased, meanwhile deduced H2 production and the consumption of glucose are increased markedly by 2.8 fold and 1 fold, and the ratio of acetate/ethanol is enhanced froml to 1.7.

Simultaneous denitrification and methanogenesis were accomplished in a single upflow sludge blanket (USB) reactor. More than 99% and 95% of nitrate and chemical oxygen demand (COD) removal rates were obtained at a loading of 600 mg NO3-N/L x d and 3,300 mg COD/L x d, respectively. The specific denitrification rate (SDR) increased as COD/NO3-N ratios decreased. Maximum SDR with acetate could reach 1.05 g NO3-N/gVSS x d. Significant sludge flotation was observed at the top of the reactor due to the change of microbial composition and the formation of hollow granules. Granules became fluffy and buoyant due to the growth of denitrifiers. Microscopic examination showed that granules exhibited layered structure and they were mainly composed of Methanosarcina sp., Pseudomonas sp., and rod-shaped bacteria.

A novel Gram-positive, anaerobic and thermophilic bacterium, strain MET79(T), was isolated from an oil well located in the Gulf of Mexico. Cells were straight rods, motile by a subpolar flagellum. Spores were formed in old cultures. Inner gas vacuoles swelled the cells when exposed to air. The optimum growth conditions were 55 degrees C, pH 7.5 and 1 % NaCl. Yeast extract was required for growth. Strain MET79(T) fermented several sugars, some organic acids and Casamino acids. Glucose was fermented into lactate, acetate, butyrate, H(2) and CO(2). Strain MET79(T) reduced thiosulfate to hydrogen sulfide and nitrate to ammonium. The DNA G+C content was 30.9 mol%. The closest phylogenetic relative of strain MET79(T) was Caloranaerobacter azorensis (88.7 % 16S rDNA sequence similarity). As strain MET79(T) (=DSM 15102(T)=CIP 107615(T)) was physiologically and phylogenetically different from its closest relatives, it is assigned as the type strain of a novel species of a new genus, Garciella nitratireducens gen. nov., sp. nov.

The use of 20 amino acids by butyrate-producing asaccharolytic anaerobic Gram-positive rods (AAGPRs) in periodontal pockets, i.e. Eubacterium minutum, Filifactor alocis, E. infirmum, E. sulci and E. saphenum, was studied. E. minutum used only arginine and lysine, and produced substantial amounts of butyrate and ammonia as the main metabolic products from arginine, and acetate, butyrate and ammonia from lysine. Fi. alocis used arginine alone and produced butyrate and ammonia. E. infirmum, E. sulci and E. saphenum used lysine alone and produced acetate, butyrate and ammonia. The growth of these bacterial species was supported and enhanced by arginine and/or lysine enriched to culture media, but not by the other amino acids. Arginine deiminase, ornithine carbamoyltransferase and carbamate kinase activity were detected in the cell-free extract of E. minutum, suggesting that arginine was metabolised to citrulline initially, and subsequently to ornithine and carbamoyl phosphate. Ornithine and carbamoyl phosphate were further converted to butyrate, and carbon dioxide and ammonia, respectively. Enzymatic activity of arginine deiminase and ornithine carbamoyltransferase was not detected in Fi. alocis, indicating that Fi. alocis converted arginine to ornithine directly, not via citrulline, and further to butyrate.

Growth physiology of the iron-reducing bacteria Thermoterrabacterium ferrireducens and Thermoanaerobacter siderophilus was investigated. The stimulation of the organotrophic growth of T. ferrireducens and T. siderophilus in the presence of Fe(III) was shown to be due to the utilization of ferric iron as an electron acceptor in catabolic processes and not to the effect exerted on the metabolism by Fe(II) or by changes in the redox potential. It was established that Fe(III) reduction in T. ferrireducens is not a detoxication strategy. In T. siderophilus, this process is carried out to relieve the inihibitory effect of hydrogen. T. ferrireducens was shown to be capable of lithoautotrophic growth with molecular hydrogen as electron donor and amorphous ferric oxide as electron acceptor, in the absence of any organic substances. The minimum threshold of H2 consumption was 3 x 10(-5) vol % of H2. The presence of CO dehydrogenase activity in T. ferrireducens suggests that CO2 fixation in this organism involves the anaerobic acetyl-CoA pathway. T. siderophilus failed to grow under lithoautotrophic conditions. The fact that T. ferrireducens contains c-type cytochromes and T. sidrophilus lacks them confirms the operation of different mechanisms of ferric iron reduction in these species.

A novel anaerobic, thermophilic, CO-utilizing bacterium, strain 41(T), was isolated from a terrestrial hot vent on the Kamchatka Peninsula. Strain 41(T) was found to be a Gram-positive bacterium, its cells being short, straight, motile rods. Chains of three to five cells were often observed. The isolate grew only chemolithoautotrophically on CO, producing equimolar quantities of H2 and CO2 (according to the equation CO+H2O --> CO2+H2). Growth was observed in the temperature range 40-68 degrees C, with an optimum at 58 degrees C, and in the pH range 6.5-7.6, with an optimum at pH 7.0. The generation time under optimal conditions for chemolithotrophic growth was 1.1 h. The DNA G+C content was 46 +/- 1 mol%. Growth was completely inhibited by penicillin, ampicillin, streptomycin, kanamycin and neomycin. On the basis of the phenotypic and phylogenetic features, it is proposed that this isolate represents a new genus and species, Carboxydocella thermautotrophica gen. nov., sp. nov. (type strain 41(T) = DSM 12356(T) = VKM B-2282(T)).

Five strains of butyrate-producing, anaerobic, gram-positive bacteria were isolated from human faecal material. These strains were slightly curved rods that showed motility by means of multiple subterminal flagella. The DNA G + C content of the strains was 29-31 mol%. A detailed investigation of the phenotypic and phylogenetic characteristics of the strains revealed that they represent a novel species of anaerobic, low-G+C-content, butyrate-producing bacterium that shows net acetate utilization during growth on media containing carbohydrates and short-chain fatty acids. The 16S rRNA gene sequences of the five isolates were determined and they confirmed that these strains were closely related to each other. Phylogenetic analysis indicated that the most closely related species are Eubacterium rectale, Eubacterium oxidoreducens and Roseburia cecicola, members of cluster XIVa of the Clostridium subphylum of gram-positive bacteria, although they share less than 95% sequence identity with the novel strains. It is proposed that a novel species, Roseburia intestinalis sp. nov., be created, with strain L1-82T (= DSM 14610T = NCIMB 13810T) as the type strain.

Phylogenetic analysis of the 16S rRNA gene of bacterial isolates from garden soil showed relatedness to Weissella kandleri and Weissella confusa. However, the sequences had notable differences, and DNA-DNA hybridizations confirmed that the isolates are separate from these two species. The isolates could be further distinguished from all previously described Weissella species by electrophoretic analysis of whole-cell proteins, as well as by the results from different biochemical tests. The name Weissella soli is proposed for the new species, the type strain being Mi268T (= LMG 20113T = DSM 14420T).

2-Phenoxyethanol is converted into phenol and acetate by a strictly anaerobic Gram-positive bacterium, Acetobacterium strain LuPhet1. Acetate results from oxidation of acetaldehyde that is the early product of the biodegradation process (Frings, J., and Schink, B. (1994) Arch. Microbiol. 162, 199-204). Feeding experiments with resting cell suspensions and 2-phenoxyethanol bearing two deuterium atoms at either carbon of the glycolic moiety as substrate demonstrated that the carbonyl group of the acetate derives from the alcoholic function and the methyl group derives from the adjacent carbon. A concomitant migration of a deuterium atom from C-1 to C-2 was observed. These findings were confirmed by NMR analysis of the acetate obtained by fermentation of 2-phenoxy-[2-(13)C,1-(2)H(2)]ethanol, 2-phenoxy-[1-(13)C,1-(2)H(2)]ethanol, and 2-phenoxy-[1,2-(13)C(2),1-(2)H(2)]ethanol. During the course of the biotransformation process, the molecular integrity of the glycolic unit was completely retained, no loss of the migrating deuterium occurred by exchange with the medium, and the 1,2-deuterium shift was intramolecular. A diol dehydratase-like mechanism could explain the enzymatic cleavage of the ether bond of 2-phenoxyethanol, provided that an intramolecular H/OC(6)H(5) exchange is assumed, giving rise to the hemiacetal precursor of acetaldehyde. However, an alternative mechanism is proposed that is supported by the well recognized propensity of alpha-hydroxyradical and of its conjugate base (ketyl anion) to eliminate a beta-positioned leaving group.

Dissimilatory arsenate-reducing bacteria have been implicated in the mobilization of arsenic from arsenic-enriched sediments. An As(V)-reducing bacterium, designated strain GBFH, was isolated from arsenic-contaminated sediments of Lake Coeur d'Alene, Idaho. Strain GBFH couples the oxidation of formate to the reduction of As(V) when formate is supplied as the sole carbon source and electron donor. Additionally, strain GBFH is capable of reducing As(V), Fe(III), Se(VI), Mn(IV) and a variety of oxidized sulfur species. 16S ribosomal DNA sequence comparisons reveal that strain GBFH is closely related to Desulfitobacterium hafniense DCB-2(T) and Desulfitobacterium frappieri PCP-1(T). Comparative physiology demonstrates that D. hafniense and D. frappieri, known for reductively dechlorinating chlorophenols, are also capable of toxic metal or metalloid respiration. DNA-DNA hybridization and comparative physiological studies suggest that D. hafniense, D. frappieri, and strain GBFH should be united into one species. The isolation of an Fe(III)- and As(V)-reducing bacterium from Lake Coeur d'Alene suggests a mechanism for arsenic mobilization in these contaminated sediments while the discovery of metal or metalloid respiration in the genus Desulfitobacterium has implications for environments cocontaminated with arsenious and chlorophenolic compounds.

A new anaerobic, thermophilic, CO-utilizing marine bacterium, strain JMT, was isolated from a submarine hot vent in Okinawa Trough. Cells of strain JMT were non-motile thin straight rods, sometimes branching, with a cell wall of the Gram-positive type, surrounded with an S-layer. Chains of three to five cells were often observed. The isolate grew chemolithotrophically on CO, producing equimolar quantities of H2 and CO2 (according to the equation CO+H2O-->CO2+H2) and organotrophically on peptone, yeast extract, starch, cellobiose, glucose, galactose, fructose and pyruvate, producing H2, acetate and CO2. Growth was observed from 50 to 80 degrees C with an optimum at 70 degrees C. The optimum pH was 6.8-7.1. The optimum concentration of sea salts in the medium was 20.5-25.5 g l(-1). The generation time under optimal conditions was 7.1 h. The DNA G+C content was 33 mol %. Growth of isolate JMT was not inhibited by penicillin, but ampicillin, streptomycin, kanamycin and neomycin completely inhibited growth. The results of 16S rDNA sequence analysis revealed that strain JMT belongs to the Thermoanaerobacter phylogenetic group within the Bacillus-Clostridium subphylum of Gram-positive bacteria but represents a separate branch of this group. On the basis of morphological and physiological features and phylogenetic data, this isolate should be assigned to a new genus, for which the name Carboxydobrachium is proposed. The type species is Carboxydobrachium pacificum; the type strain is JMT (= DSM 12653T).

The demethylation of the algal osmolyte dimethylsulfoniopropionate (DMSP) to methylthiopropionate (MTPA) by (homo)acetogenic bacteria was studied. Five Eubacterium limosum strains (including the type strain), Sporomusa ovata DSM 2662(T), Sporomusa sphaeroides DSM 2875(T), and Acetobacterium woodii DSM 1030(T) were shown to demethylate DMSP stoichiometrically to MTPA. The (homo)acetogenic fermentation based on this demethylation did not result in any significant increase in biomass. The analogous demethylation of glycine betaine to dimethylglycine does support growth of acetogens. In batch cultures of E. limosum PM31 DMSP and glycine betaine were demethylated simultaneously. In mixed substrates experiments with fructose-DMSP or methanol-DMSP, DMSP was used rapidly but only after exhaustion of the fructose or the methanol. In steady-state fructose-limited chemostat cultures (at a dilution rate of 0.03 h(-1)) with DMSP as a second reservoir substrate, DMSP was biotransformed to MTPA but this did not result in higher biomass values than in cultures without DMSP; cells from such cultures demethylated DMSP at rates of approximately 50 nmol min(-1) mg of protein(-1), both after growth in the presence of DMSP and after growth in its absence. In cell extracts of glycine betaine-grown strain PM31, DMSP demethylation activities of 21 to 24 nmol min(-1) mg of protein(-1) were detected with tetrahydrofolate as a methyl acceptor; the activities seen with glycine betaine were approximately 10-fold lower. A speculative explanation for the demethylation of DMSP without an obvious benefit for the organism is that the DMSP-demethylating activity is catalyzed by the glycine betaine-demethylating enzyme and that a transport-related factor, in particular a higher energy demand for DMSP transport across the cytoplasmic membrane than for glycine betaine transport, may reduce the overall ATP yield of the fermentation to virtually zero.

From the rat intestinal microflora we isolated a gram-positive rod, termed HDCA-1, that is a member of a not previously described genomic species and that is able to transform the 3alpha,6beta, 7beta-trihydroxy bile acid beta-muricholic acid into hyodeoxycholic acid (3alpha,6alpha-dihydroxy acid) by dehydroxylation of the 7beta-hydroxy group and epimerization of the 6beta-hydroxy group into a 6alpha-hydroxy group. Other bile acids that were also transformed into hyodeoxycholic acid were hyocholic acid (3alpha, 6alpha,7alpha-trihydroxy acid), alpha-muricholic acid (3alpha,6beta, 7alpha-trihydroxy acid), and omega-muricholic acid (3alpha,6alpha, 7beta-trihydroxy acid). The strain HDCA-1 could not be grown unless a nonconjugated 7-hydroxylated bile acid and an unidentified growth factor produced by a Ruminococcus productus strain that was also isolated from the intestinal microflora were added to the culture medium. Germfree rats selectively associated with the strain HDCA-1 plus a bile acid-deconjugating strain and the growth factor-producing R. productus strain converted beta-muricholic acid almost completely into hyodeoxycholic acid.

We examined the relative roles of acetogenic and sulfate-reducing bacteria in H2 consumption in a previously characterized subsurface sandstone ecosystem. Enrichment cultures originally inoculated with ground sandstone material obtained from a Cretaceous formation in central New Mexico were grown with hydrogen in a mineral medium supplemented with 0.02% yeast extract. Sulfate reduction and acetogenesis occurred in these cultures, and the two most abundant organisms carrying out the reactions were isolated. Based on 16S rRNA analysis data and on substrate utilization patterns, these organisms were named Desulfomicrobium hypogeium sp. nov. and Acetobacterium psammolithicum sp. nov. The steady-state H2 concentrations measured in sandstone-sediment slurries (threshold concentration, 5 nM), in pure cultures of sulfate reducers (threshold concentration, 2 nM), and in pure cultures of acetogens (threshold concentrations 195 to 414 nM) suggest that sulfate reduction is the dominant terminal electron-accepting process in the ecosystem examined. In an experiment in which direct competition for H2 between D. hypogeium and A. psammolithicum was examined, sulfate reduction was the dominant process.

Diisopropanolamine (DIPA) is a "sweetening agent" used to remove hydrogen sulfide from sour natural gas, and it is a contaminant at some sour gas treatment facilities in western Canada. To investigate the biodegradation of this alkanolamine, 14C-DIPA was used in anaerobic and aerobic mineralization studies. Between 3 and 78% of the radioactivity from this compound was released as 14CO2 in sediment-enrichment cultures incubated under nitrate-reducing conditions. Similarly, 12-78% of the label was converted to 14CO2 in sediment-enrichment cultures incubated under Mn(IV)-reducing conditions. These activities were observed at 8 degrees C, a typical groundwater temperature in western Canada, and at 28 degrees C. In contrast, DIPA-degrading activity was difficult to sustain under Fe(III)-reducing conditions, and < 25% of the radioactive label from 14C-DIPA was liberated as 14CO2. Two mixed cultures and two isolates (both irregular, non-sporeforming, Gram-positive rods) were used to assess aerobic mineralization of 14C-DIPA. The aerobic mixed cultures released 73 and 79% of the radioactive label as 14CO2, whereas the pure cultures liberated only 39 and 47% as 14CO2. Between one-third and one-half of the nitrogen from DIPA was found as ammonium-N in aerobic batch cultures. These results clearly demonstrate that DIPA is mineralized under a variety of incubation conditions.

Due to the difficulty of identifying Corynebacterium spp. with standard methods, we compared them with the RapID CB Plus system (Remel, Lenexa, Kans. [formerly Innovative Diagnostic Systems, Norcross, Ga.]), which consists of 4 carbohydrate and 14 preformed enzyme tests, for the identification of 98 clinical isolates of Corynebacterium sp., other coryneforms, Listeria monocytogenes, and 17 ATCC strains. Forty (95%) of 42 strains of Corynebacterium spp. were accurately identified to the species level by the RapID CB Plus system, and two additional strains of C. striatum were identified with one additional conventional test for lipid requirement. Twenty-seven (75%) of the 36 coryneform strains tested were identified correctly to the species level. However, three of four strains of Brevibacterium sp. and all seven of the L. monocytogenes strains were identified to the genus level only. Actinomyces strains had variable results, and the one strain of Arcanobacterium haemolyticum tested was not identified. Overall, the RapID CB Plus system compared favorably with the conventional methods, was easy to inoculate and interpret, and is promising as a new method for identification of gram-positive bacilli.

A new gram-positive, alkaliphilic, nonsporulating, rod-shaped bacterium is described. The organism was isolated from soda soil (Lake Bogoria, Kenya) and has the following characteristics. It is nonmotile, not acid fast, halotolerant, and microaerophilic, and optimal growth occurs at pH values between 9 and 10. The peptidoglycan type is of type A4 alpha, with lysine as the characteristic diamino acid and glutamic acid as a component of the interpeptide bridge. The major menaquinone is MK-8(H4). The polar lipids are phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, and an unknown phospholipid. 12-Methyltetradecanoic acid is the predominant fatty acid. The G + C content of the DNA is 70 mol%. The results of 16S ribosomal DNA sequence comparisons revealed that strain HKI 0088T represents a new lineage in the order Actinomycetales. Therefore, we concluded that strain HKI 0088T should be assigned to a new genus and species, for which we propose the name Bogoriella caseilytica gen. nov., sp. nov. The type strain and only strain of this genus and species is HKI 0088 (= DSM 11294).

A strain of a thermophilic, anaerobic, dissimilatory, Fe(III)-reducing bacterium, Thermoterrabacterium ferrireducens gen. nov., sp. nov. (type strain JW/AS-Y7T; DSM 11255), was isolated from hot springs in Yellowstone National Park and New Zealand. The gram-positive-staining cells occurred singly or in pairs as straight to slightly curved rods, 0.3 to 0.4 by 1.6 to 2.7 microns, with rounded ends and exhibited a tumbling motility. Spores were not observed. The temperature range for growth was 50 to 74 degrees C with an optimum at 65 degrees C. The pH range for growth at 65 degrees C was from 5.5 to 7.6, with an optimum at 6.0 to 6.2. The organism coupled the oxidation of glycerol to reduction of amorphous Fe(III) oxide or Fe(III) citrate as an electron acceptor. In the presence as well as in the absence of Fe(III) and in the presence of CO2, glycerol was metabolized by incomplete oxidation to acetate as the only organic metabolic product; no H2 was produced during growth. The organism utilized glycerol, lactate, 1,2-propanediol, glycerate, pyruvate, glucose, fructose, mannose, and yeast extract as substrates. In the presence of Fe(III) the bacterium utilized molecular hydrogen. The organism reduced 9,10-anthraquinone-2,6-disulfonic acid, fumarate (to succinate), and thiosulfate (to elemental sulfur) but did not reduce MnO2, nitrate, sulfate, sulfite, or elemental sulfur. The G + C content of the DNA was 41 mol% (as determined by high-performance liquid chromatography). The 16S ribosomal DNA sequence analysis placed the isolated strain as a member of a new genus within the gram-type-positive Bacillus-Clostridium subphylum.

BALB/cA mice were examined for the effects of chronic isoproterenol treatment or submandibular-sublingual gland ablation on the natural patterns of oral bacterial colonization on tooth surfaces. Indigenous microflora on the tooth surfaces of BALB/cA mice was relatively simple. The predominant bacterial groups were Enterobacteriaceae (45.9%), enterococci (29.4%) and staphylococci (15.7%). Isoproterenol, which resulted in the induced synthesis of proline-rich proteins, caused a decrease in the total cultivable bacteria on the tooth surfaces. The proportion of Enterobacteriaceae in the isoproterenol-treated mice decreased, although the proportion of other bacterial groups increased. Salivary gland ablation, which caused the loss of mucins in saliva, showed essentially the same number of total bacteria as the control. Salivary gland ablation resulted in a decrease in the proportion of Enterobacteriaceae, while the proportion of Gram-positive rods and staphylococci increased.

The four decades of the now classic studies by Harland G. Wood and Lars G. Ljungdahl lead to the resolution of the autotrophic acetyl-CoA 'Wood/Ljungdahl' pathway of acetogenesis. This pathway is the hallmark of acetogens, but is also used by other bacteria, including methanogens and sulfate-reducing bacteria, for both catabolic and anabolic purposes. Thus, the pathway is wide spread in nature and plays an important role in the global turnover of carbon. Because most historical studies with acetogens focused on the biochemistry of the acetyl-CoA pathway, the metabolic diversity and ecology of acetogens remained largely unexplored for many years. Although acetogens were initially conceived to be a somewhat obscure bacteriological group with limited metabolic capabilities, it is now clear that acctogens are arguably the most metabolically diverse group of obligate anaerobes characterized to date. Their anaerobic metabolic arsenal includes the capacity to oxidize diverse substrates, including aromatic, C1, C2, and halogenated compounds, and engage a large number of alternative energy-conserving, terminal electron-accepting processes, including classic fermentations and the dissimilation of inorganic nitrogen. In this regard, one might consider acetogens on a collective basis as the pseudomonads of obligate anaerobes. By virtue of their diverse metabolic talents, acetogens can be found in essentially all habitats. This review evaluates the metabolic versatilities of acetogens relative to both the engagement (regulation) of the acetyl-CoA pathway and the ecological roles likely played by this bacteriogical group.

16S rRNA gene sequences of the type strains of the seven previously described Acetobacterium species were determined. The Acetobacterium species were found to form a tight phylogenetic cluster within the Clostridium subphylum of the gram-positive bacteria. Within this subphylum these organisms belong to cluster XV as defined by Collins et al. (M.D. Collins, P.A. Lawson, A. Willems, J.J. Cordoba, J. Fernandez-Garayzabal, P. Garcia, J. Cai, H. Hippe, and J. A. E. Farrow, Int. J. Syst. Bacteriol. 44:812-826, 1994) together with Eubacterium alactolyticum barkeri, Eubacterium callanderi, and Eubacterium limosum. Our data indicate that Clostridium cluster XV consists of at least the following three genera: the genus Acetobacterium, the genus Eubacterium sensu stricto (comprising E. limosum, E. barkeri, and E. callanderi), and the genus Pseudoramibacter gen. nov., which is created for E. alactolyticum, which we reclassify as Pseudoramibacter alactolyticus comb. nov.

The purpose of this work was to study H2/CO2-utilizing acetogenic population in the colons of non-methane-producing individuals harboring low numbers of methanogenic archaea. Among the 50 H2-consuming acetogenic strains isolated from four fecal samples and an in vitro semi-continuous culture enrichment, with H2/CO2 as sole energy source, 20 were chosen for further studies. All isolates were Gram-positive strict anaerobes. Different morphological types were identified, providing evidence of generic diversity. All acetogenic strains characterized used H2/CO2 to form acetate as the sole metabolite, following the stoichiometric equation of reductive acetogenesis. These bacteria were also able to use a variety of organic compounds for growth. The major end product of glucose fermentation was acetate, except for strains of cocci that mainly produced lactate. Yeast extract was not necessary, but was stimulatory for growth and acetogenesis from H2/CO2.

An identification scheme for aerobically growing Gram-positive rods (genera Actinomyces, Arcanobacterium, Aureobacterium, Bacillus, Brevibacterium, Cellulomonas, Corynebacterium, Dermabacter, Erysipelothrix, Gardnerella, Lactobacillus, Listeria, Microbacterium, Oerskovia, Propionibacterium, Rhodococcus, Rothia, Turicella, as well as unnamed CDC groups, Clostridium tertium, and Mycobacterium fortuitum/chelonae) is presented. It is derived from the Hollis-Weaver scheme and uses catalase, oxidative/fermentative carbohydrate metabolism and motility as primary reactions. Tests for lipophilism, nitrate reduction, urease, esculin hydrolysis, the CAMP reaction, acid formation from five carbohydrates, as well as for some facultative reactions should lead to a correct diagnosis based on information available at the end of 1995.

This study concerns the apical border (AB) plaque in relation to severe forms of periodontitis (SP), including juvenile, post-juvenile, and rapidly progressing periodontitis. Twenty-four (24) teeth from 16 patients with SP were examined by transmission electron microscopy (TEM). The AB was not discrete, with islands of bacteria in the so-called plaque-free zone (PFZ). Coronal to the AB the established plaque consisted of a layer of Gram-positive cocci and ghost cells and a superficial layer mainly of Gram-negative morphotypes, including cocci, rods, filaments, fusiforms, and spirochetes. The most apical apparently intact organisms in the PFZ were in bacterial islands or in isolation and were predominantly Gram-negative cocci and rods, with ghost cells in abundance. Ruthenium red, alcian blue-lanthanum nitrate, and safranin O were used to label matrix polyanionic macromolecules, and periodic acid (thiosemicarbazide) silver proteinate for intracellular polysaccharide (IPS). The matrix components were mainly fibrillar. Many intact bacteria exhibited extracellular polysaccharides or glycocalyces associated with their cell wall, and cytoplasmic IPS granules. The latter varied in distribution and were evident even in the most apically advanced intact microorganisms. The results indicate that IPS and some matrix features of the apical border plaque in severe periodontitis in certain aspects resemble those of sub-contact area plaque on children's teeth, in health or associated with early chronic gingivitis, and with those in chronic adult periodontitis. They also suggest the establishment of acidic regions in the microniche at the bottom of the periodontal pocket in the various forms of periodontitis differing in rate of progression. It was concluded that there was a limited range of intact bacterial morphotypes in the apical border plaque in severe periodontitis, similar to those in chronic adult periodontitis.

Bacterial deglycosylation of immunoglobulin Al (IgA1), the dominant isotype of antibody in the oral cavity, probably provides both nutrition as well as protection to the oral bacterial community. Representative strains of oral gram-positive rods were tested for their ability to remove carbohydrates from IgA1. Detection of sialic acids was performed by means of high-performance liquid chromatography (HPLC) separation (Aminex HPX-87H) and ultraviolet light absorption at 190 nm, and neutral carbohydrates were measured by HPLC separation (Capcell Pak C-18 SG 120) and ultraviolet light absorption at 245 nm after derivatization. Four strains of Actinomyces naeslundii, two strains of Corynebacterium matruchotii and one of two strains of Actinomyces odontolyticus partially or totally removed sialic acid, while two strains of Propionibacterium propionicus and the other strain of A. odontolyticus did not. Complete correlation was observed between sialic acid removal, neuraminidase activity measured with fluorogenic substrate and with one exception, altered immunoelectrophoretic mobility of IgA1. Only limited removal of other carbohydrates was observed with poor correlation to exoglycosidase activities measured with chromogenic substrates. Desialylation increases the susceptibility of glycoproteins, including IgA1, to proteolysis. Therefore, the desialylation of IgA1 by oral gram-positive rods may facilitate the proteolytic activities of other oral bacteria, and the concerted action may positively influence the survival of the bacteria in the oral community.

With triethanolamine as sole source of energy and organic carbon, a strictly anaerobic, gram-positive, rod-shaped bacterium, strain LuTria 3, was isolated from sewage sludge and was assigned to the genus Acetobacterium on the basis of morphological and physiological properties. The G+C content of the DNA was 34.9 +/- 1.0 mol %. The new isolate fermented triethanolamine to acetate and ammonia. In cell-free extracts, a triethanolamine-degrading enzyme activity was detected that formed acetaldehyde as reaction product. Triethanolamine cleavage was stimulated 30-fold by added adenosylcobalamin (co-enzyme B12) and inhibited by cyanocobalamin or hydroxocobalamin. Ethanolamine ammonia lyase, acetaldehyde:acceptor oxidoreductase, phosphate acetyltransferase, acetate kinase, and carbon monoxide dehydrogenase were measured in cell-free extracts of this strain. Our results establish that triethanolamine is degraded by a corrinoid-dependent shifting of the terminal hydroxyl group to the subterminal carbon atom, analogous to a diol dehydratase reaction, to form an unstable intermediate that releases acetaldehyde. No anaerobic degradation of triethylamine was observed in similar enrichment assays.

A strictly anaerobic gram-positive, rod-shaped bacterium, strain LuPhet1, was isolated from sewage sludge with phenoxyethanol as sole carbon and energy source, and was assigned to the genus Acetobacterium. The new isolate fermented the alkylaryl ether compound phenoxyethanol stoichiometrically to phenol and acetate, whereas phenoxyacetic acid was not degraded. In cell-free extracts of strain LuPhet1, cleavage of the ether linkage was shown, and acetaldehyde was detected as reaction product. Coenzyme A-dependent acetaldehyde: acceptor oxidoreductase, phosphate acetyltransferase, acetate kinase, and carbon monoxide dehydrogenase were measured in cell-free extracts of this strain. Our results indicate that the ether linkage of phenoxyethanol is cleaved by a shift of the hydroxyl group to the subterminal carbon atom, analogous to a corrinoid-dependent diol dehydratase reaction, to form an unstable hemiacetal that releases phenol and acetaldehyde. Obviously, phenoxyethanol is degraded by the same strategy as in anaerobic degradation of the alkyl ether polyethylene glycol.

Brochotrix campestris ATCC 43754 produces a bacteriocin inhibitory towards Brochothrix thermosphacta, lactobacilli, Listeria spp., and other gram-positive bacteria. This antimicrobial agent is heat stable, sensitive to proteases, catalase insensitive, and free of organic acids. No phage particles were detected by transmission electron microscopy. Muramidase activity was not detected in the preparations. On the basis of established criteria, the antimicrobial agent was classified as a bacteriocin and named brochocin-C.

Fifteen strains of eugonic, nonoxidative, gram-negative rods isolated primarily from human wounds of the extremities and blood formed a distinct group which was designated Gilardi rod group 1. The phenotypic characteristics of Gilardi rod group 1 were most similar to those of CDC group M-5, with the major difference that nitrite reduction was observed with CDC group M-5. All 15 strains of Gilardi rod group 1 possessed a distinct fatty acid profile which was characterized by large amounts (> 15%) of cis-vaccenic (18:1 omega 7c), palmitic (16:0), myristic (14:0), and lactobacillic (19:0 cyc11,12) acids and moderate amounts (3 to 5%) of lauric (12:0), 3-hydroxylauric (3-OH-12:0), and palmitoleic (16:1 omega 7c) acids. This fatty acid profile is unique compared with the profiles of CDC group M-5 and other bacteria we have tested and is useful for the rapid identification of Gilardi rod group 1 isolates.

The carbon kinetic isotope effects associated with synthesis of acetate from CO2 and H2 during autotrophic growth of Acetobacterium woodii at 30 degrees C have been measured by isotopic analyses of CO2, methyl-carbon, and total acetate. Closed systems allowing construction of complete mass balances at varying stages of growth were utilized, and the effects of the partitioning of carbon between CO2 and HCO3- were taken account. For the overall reaction, total carbonate --> total acetate, isotope effects measured in replicate experiments ranged from -59.0 +/- 0.9% to -57.2 +/- 2.3%. Taking into account all measurements, the weighted mean and standard deviation are -58.6 +/- 0.7%. There is no evidence for intramolecular ordering in the acetate. The carbon isotopic composition of sedimentary acetate, otherwise expected to be near that of sedimentary organic carbon, is likely to be depleted in environments in which autotrophic acetogenesis is occurring.