Showing papers by "Bharat K. C. Patel published in 2004"

Isolation from oil reservoirs of novel thermophilic anaerobes phylogenetically related to Thermoanaerobacter subterraneus: reassignment of T. subterraneus, Thermoanaerobacter yonseiensis, Thermoanaerobacter tengcongensis and Carboxydibrachium pacificum to Caldanaerobacter subterraneus gen. nov., sp. nov., comb. nov. as four novel subspecies

Abstract: Novel thermophilic, anaerobic, Gram-positive, rod-shaped bacteria, strains SL9 and OCA1, were isolated from oilfields in France and Australia, respectively. Both strains, together with Thermoanaerobacter yonseiensis KB-1(T) (=DSM 13777(T)), Thermoanaerobacter tengcongensis MB4(T) (=DSM 15242(T)) and Carboxydibrachium pacificum JM(T) (=DSM 12653(T)), possessed genomic (DNA-DNA hybridization studies) and phylogenetic similarities with Thermoanaerobacter subterraneus SEBR 7858(T) (=DSM 13054(T)), which was isolated recently from an oilfield reservoir in south-west France. Marked phenotypic differences exist between the three oilfield isolates (T. subterraneus, strain OCA1 and strain SL9): they include temperature range for growth and substrates used. Differences were also observed in the DNA G+C contents of all organisms. Similarly to T. subterraneus, strains SL9 and OCA1, and also T. yonseiensis, T. tengcongensis and Carboxydibrachium pacificum, produced acetate and L-alanine as major end products of glucose metabolism [0.8-1.0 mol L-alanine produced (mol glucose consumed)(-1)] and reduced thiosulfate, but not sulfate, to sulfide. Because of these significant metabolic and phylogenetic differences between the oilfield isolates (T. subterraneus, strain OCA1 and strain SL9), T. yonseiensis, T. tengcongensis and Carboxydibrachium pacificum and other Thermoanaerobacter species, it is proposed to reassign them as a novel genus and species, Caldanaerobacter subterraneus gen. nov., sp. nov., comb. nov., with the creation of four novel subspecies, Caldanaerobacter subterraneus subsp. subterraneus subsp. nov., comb. nov., Caldanaerobacter subterraneus subsp. yonseiensis subsp. nov., comb. nov., Caldanaerobacter subterraneus subsp. tengcongensis subsp. nov., comb. nov. and Caldanaerobacter subterraneus subsp. pacificus subsp. nov., comb. nov.

Petrobacter succinatimandens gen. nov., sp. nov., a moderately thermophilic, nitrate-reducing bacterium isolated from an Australian oil well.

Abstract: A novel Gram-negative, aerobic and moderately thermophilic bacterium, strain 4BON(T), was isolated from a non-water-flooded Australian terrestrial oil reservoir. Cells were non-spore-forming straight rods, which were motile by means of a polar flagellum. The optimum growth conditions were 55 degrees C, pH 6.9 and 0.5 % NaCl. Strain 4BON(T) was oxidase- and catalase-positive; it grew on fumarate, pyruvate, succinate, formate, ethanol and yeast extract in the presence of oxygen or nitrate as terminal electron acceptor. Nitrate was reduced to nitrous oxide. The DNA G+C content of the strain was 58.6 mol%. The closest phylogenetic relative of strain 4BON(T) was Hydrogenophilus thermoluteolus (similarity of 91.8 %), of the beta-Proteobacteria. As strain 4BON(T) is physiologically and phylogenetically different from H. thermoluteolus, it is proposed that it be assigned to a novel species of a novel genus, Petrobacter succinatimandens gen. nov., sp. nov. The type strain is 4BON(T) (=DSM 15512(T)=CIP 107790(T)).

Phenylobacterium lituiforme sp. nov., a moderately thermophilic bacterium from a subsurface aquifer, and emended description of the genus Phenylobacterium.

Abstract: A facultative anaerobic bacterium, strain FaiI3(T), was isolated from samples collected from the free-flowing waters of a bore well (Fairlea Bore, registration number 3768) which taps into the Australian Great Artesian Basin subsurface thermal aquifer. Strain FaiI3(T) developed yellow to pale-yellow colonies (0.5-1.5 mm) after 48 h. The non-spore forming rods (0.5x1-3 microm) were slightly curved, occurred singly and as pairs and were motile with a single polar flagellum. Cells tended to form clumps in liquid medium and rosettes were commonly observed. The cells stained Gram-negative and electron micrographs of thin sections revealed a multi-layered complex Gram-negative cell wall structure. Strain FaiI3(T) grew optimally at 40-41 degrees C, with growth observed at 45 degrees C but not at 50 degrees C. The pH growth range was between pH 6 and 9 and optimal growth occurred between pH 6 and 6.5. Strain FaiI3(T) grew best with yeast extract as the sole carbon and energy source. Peptone, yeast extract, acetate, xylose, sucrose, glucose, glycerol, succinate, butyrate, lactate, fumarate, citrate, L-phenylalanine, cellobiose and gelatin supported growth but maltose, fructose, glycine, ethanol, benzoate and oxalate did not. Tyrosine was produced from L-phenylalanine. Strain FaiI3(T) was catalase-positive and oxidase-negative and did not hydrolyse starch. Growth was inhibited by neomycin, tetracycline, streptomycin, chloramphenicol, ampicillin, vancomycin and spectinomycin. The G+C content was determined to be 66.5+/-0.5 mol%. On the basis of the 16S rRNA gene sequence analysis, strain FaiI3(T) was assigned as a novel species of the genus Phenylobacterium, Phenylobacterium lituiforme sp. nov. in the order Caulobacterales, subclass alpha-Proteobacteria, class Proteobacteria. The type strain is FaiI3(T) (=ATCC BAA-294(T)=DSM 14363(T)).

Mahella australiensis gen. nov., sp. nov., a moderately thermophilic anaerobic bacterium isolated from an Australian oil well.

Abstract: A novel Gram-positive, anaerobic and moderately thermophilic bacterium, strain 50-1 BONT, was isolated from an Australian terrestrial oil reservoir. Cells were spore-forming straight rods, motile by peritrichous flagella. The optimum growth conditions were 50 °C, pH 7·5 and 0·1 % NaCl. Strain 50-1 BONT fermented arabinose, cellobiose, fructose, galactose, glucose, mannose, sucrose, xylose and yeast extract. Glucose was fermented mainly into lactate, formate, hydrogen and CO2. The major end product of pyruvate fermentation was acetate together with H2 and CO2. Thiosulfate, sulfate, elemental sulfur and nitrate were not used as terminal electron acceptors. The DNA G+C content was 55·5 mol%. The closest phylogenetic relative of strain 50-1 BONT was Thermoanaerobacterium thermosulfurigenes (16S rRNA gene sequence similarity of 85·7 %). As strain 50-1 BONT was physiologically and phylogenetically different from members of the order ‘Thermoanaerobacteriales’, it is proposed that strain 50-1 BONT (=DSM 15567T=CIP 107919T) be classified as the type strain of a novel species of a new genus, Mahella australiensis gen. nov., sp. nov.

Iron-reducing bacteria: Ecology, significance and potential uses

Abstract: Iron-reducing bacteria are able to couple the oxidation of an electron donor to the reduction of Fe(III) to Fe(II) under anaerobic conditions in the generation of cellular energy. Recent evidence suggests that these bacteria are phylogenetically diverse and widely distributed in nature. Our laboratory has isolated thermophilic, thermotolerant and mesophilic iron-reducing bacteria from numerous petroleum reservoirs with varying conditions, groundwaters of the Great Artesian Basin (GAB), and petroleum-contaminated soils. Some of these isolates have been identified as novel species and from genera such as Deferribacter, Bacillus, Alkaliphilus, Clostridium and Thermoanaerobacter. Further investigations have shown that these bacteria are metabolically diverse, not only capable of reducing different metal species but also able to use a range of organic compounds, including polycyclic aromatic hydrocarbons, for growth. Due to their abundance and metabolic capabilities, it is possible that iron-reducing bacteria may be important in microbially-enhanced oil recovery processes and in the bioremediation of contaminated soils and aquifers, particularly in anaerobic zones.