Thermomonas haemolytica gen. nov., sp. nov., a gamma-proteobacterium from kaolin slurry.

Four aerobic, gram-negative bacterial strains isolated from kaolin slurry used in the production of paper were subjected to a polyphasic analysis and characterization to determine their taxonomic position. Analysis of the 16S rDNA sequences of the four strains revealed that they represent a new lineage within the gamma-Proteobacteria, related to the genera Xanthomonas, Pseudoxanthomonas, Stenotrophomonas, Luteimonas, Xylella and Rhodanobacter. Analysis of the quinone system, the polyamines, the fatty acids and the polar lipids revealed a combination of characteristics that is unique and not described for the phylogenetic relatives. The four strains contain a ubiquinone Q-8, spermidine as the major polyamine, diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine as the predominant polar lipids, and a fatty acid profile with predominantly iso-branched fatty acids. The G+C content of the genomic DNA was determined to be within the narrow range 67.1-68.7 mol%. Determination of DNA relatedness, as well as riboprint band patterns and amplified fragment length polymorphism profiles, clearly demonstrated that the four strains are members of a single species. Antibiotic-susceptibility patterns were identical for the four strains. Although showing a high degree of similarites in physiological and biochemical patterns, each of the four strains could be distinguished from the others on the basis of a few biochemical characteristics. On the basis of the estimates of phylogenetic relationships derived from the 16S rDNA sequence analyses, the observed chemotaxonomic characteristics and other phenotypic traits, a new genus, Thermomonas gen. nov., and species, Thermomonas haemolytica sp. nov., are proposed for the strains A50-7-3T (= DSM 13605T = LMG 19653T), B 50-7-1 (= DSM 13598 = LMG 19655), D50-7-1 (= DSM 13610 = LMG 19656) and B50-8-1 (= DSM 13599 = LMG 19654), with strain A50-7-3T as the type strain.

Riboprints as a tool for rapid preliminary identification of sphingomonads.

Fourtythree strains of the genus Sphingomonas and close relatives were subjected to riboprint analyses generated after digestion of genomic DNA with the restriction enzyme EcoRI and hybridization with E. coli rrnB operon. The majority of strains were characterized by a complex banding pattern in the riboprints. High degrees of similarities in the riboprints were only observed among strains of the same species such as S. yanoikuyae, S. aromaticivorans, S. subarctica and S. chlorophenolica. Strains of different species including close phylogenetic relatives such as S. asaccharolytica, S. mali and S. pruni were easily distinguished by the differences in the riboprints even after visual evaluation. Thus, our data demonstrate that riboprint analysis is useful for preliminary identification of new sphingomonad isolates at the species level.

Effect of aromatic compounds on cellular fatty acid composition of Rhodococcus opacus.

In cells of Rhodococcus opacus GM-14, GM-29, and 1CP, the contents of branched (10-methyl) fatty acids increased from 3% to 15 to 34% of the total fatty acids when the cells were grown on benzene, phenol, 4-chlorophenol, chlorobenzene, or toluene as the sole source of carbon and energy, in comparison with cells grown on fructose. In addition, the content of trans-hexadecenoic acid increased from 5% to 8 to 18% with phenol or chlorophenol as the carbon source. The 10-methyl branched fatty acid content of R. opacus GM-14 cells increased in a dose-related manner following exposure to phenol or toluene when toluene was not utilized as the growth substrate. The results suggest that 10-methyl branched fatty acids may participate in the adaptation of R. opacus to lipophilic aromatic compounds.

New aerobic ammonium-dependent obligately oxalotrophic bacteria: description of Ammoniphilus oxalaticus gen. nov., sp. nov. and Ammoniphilus oxalivorans gen. nov., sp. nov.

The genus Ammoniphilus is proposed for aerobic endospore-forming Gram-variable rod-shaped bacteria, which are ammonium-dependent, obligately oxalotrophic and haloalkalitolerant, oxidase- and catalase-positive, mesophilic and motile by peritrichous flagella. Cell wall contained two electron-dense layers. The external layer consists of a chain of electron-dense granules morphologically resembling the cellulosomes of Clostridium thermocellum. Two species are described, Ammoniphilus oxalaticus gen. nov., sp. nov. and Ammoniphilus oxalivorans gen. nov., sp. nov. The type strains of these species are strains RAOx-1 (= DSM 11538) and RAOx-FS (= DSM 11537), respectively. Ammoniphilus strains were isolated from the rhizosphere of sorrel (Rumex acetosa) and from decaying wood. The strains require a high concentration of ammonium ions and use oxalate as the sole organic source of carbon and energy for growth; no growth factors were required. Growth occurred at pH 6.8-9.5. The optimum temperature and pH for growth were 28-30 degrees C and 8.0-8.5. All strains grew in a saturated solution of ammonium oxalate, and tolerated 3% NaCl. Whole-cell hydrolysates contain meso-diaminopimelic acid and glucose. The menaquinone of the strains was MK 7, and the major cellular fatty acids were 12-methyl tetradecanoic, cis-hexadec-9-enoic and hexadecanoic acids. The G + C content of the DNA was 45-46 mol% for A. oxalaticus and 42 mol% for A. oxalivorans. The almost complete 16S rDNA sequence of three strains of the two species of Ammoniphilus shows that the genus falls into the radiation of the Clostridium-Bacillus subphylum of Gram-positive bacteria. The closest phylogenetic neighbour of Ammoniphilus is Oxalophagus oxalicus. The DNA-DNA hybridization value between strains RAOx-1 and RAOx-FS was 39.7%.

Utilization of Halogenated Benzenes, Phenols, and Benzoates by Rhodococcus opacus GM-14.

Strain GM-14 was isolated by selective enrichment from contaminated soil with chlorobenzene as the sole source of carbon and energy. It utilizes an exceptionally wide spectrum of haloaromatic substrates. It is a gram-positive, weakly acid-fast actinomycete, with a morphological cycle from cocci and short rods to long rods and branched filaments; it grew optimally at 28(deg)C; and it tolerated 5% NaCl in rich medium. The chemotaxonomic characteristics, the diagnostic biochemical tests, the whole-cell fatty acid composition, and 16S rDNA analysis were consistent with Rhodococcus opacus. R. opacus GM-14 grew on 48 of 117 different aromatic and haloaromatic compounds. It utilized phenol at concentrations up to 1.2 g/liter, 3- and 4-methylphenols up to 0.5 g/liter, 2- and 4-chlorophenols up to 0.25 g/liter, and 3-chlorophenol up to 0.1 g/liter. It grew in saturated aqueous solutions of benzene, chlorobenzene, and 1,3- and 1,4-dichlorobenzene (up to 13, 3, 0.5, and 0.5 g/liter, respectively). The specific growth rate of strain GM-14 on phenol and 3- and 4-chlorophenols in batch culture was 0.27 to 0.29 h(sup-1), and that on benzene and chlorobenzene was similar to the rate on fructose, i.e., 0.2 h(sup-1). The growth yield on benzene and on chlorobenzene (<=0.4 g liter(sup-1)) was 40 to 50 g (dry weight) per mol of substrate consumed, equalling 8 g of dry weight biomass per mol of substrate carbon, similar to that obtained on acetate. During growth of strain GM-14 on chlorobenzene, 1,3-dichlorobenzene, and all isomers of monochlorophenol, stoichiometric amounts of chloride were released, and 50% of the stoichiometric amount was released from 1,4-dichlorobenzene.