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A trichloroethylene (TCE)-degrading bacterium was isolated from an aquifer sample collected at a TCE-polluted site in Japan by enriching with phenol as sole carbon source. The isolate, designated strain KP23 T , was a Gram-negative, oval-shaped micro-organism. A phylogenetic study based on 16S rRNA gene sequences indicated that strain KP23 T should be placed in the genus Burkholderia. Cellular fatty acids of the strain were mainly composed of C 16 :0 , cyclopropanic acid C 17 :0 and cyclopropanic acid C 19 :0 . Strain KP23 T also contained notable amounts of C 13 :1 and C 17 :1 . The GMC content of total DNA was 64 8 mol %. Strain KP23 T oxidized various sugars and sugar alcohols as sole carbon source such as galactose, glucose, mannose, maltose, glycerol, inositol and mannitol. Comparisons of its phenotypic and genotypic characteristics with other known species belonging to the genus Burkholderia suggested that strain KP23 T represents a new species in the genus. The name Burkholderia kururiensis is proposed for this species, with strain KP23 T as the type strain (l JCM 10599 T ).Keywords : trichloroethylene degradation, Burkholderia kururiensis sp. nov., aquifer, 16S rRNA gene INTRODUCTIONTrichloroethylene (TCE) has been used as a solvent in manufacturing to clean grease from machinery all over the world. Like many other chlorinated hydrocarbons, it has become one of the most abundant environmental pollutants because of its toxic properties and widespread occurrence in soil and groundwater in many countries. TCE removal by dumping or air stripping is restricted by legislation and thus attention is now being paid to biological degradation in soil and groundwater. In the past decade, research on the application of bacteria to the aerobic biodegradation of TCE has progressed and a wide variety of microorganisms has been investigated for this purpose. Most of these bacteria belong to the Proteobacteria such as Methylococcus capsulatus (Stainthorpe et al., 1990) Abbreviations : FAME, fatty acid methyl ester ; TCE, trichloroethylene ; UQ, ubiquinone.The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain KP23 T is AB024310. OB3b (Cardy et al., 1991), Methylocystis sp. strain M (McDonald et al., 1997), Pseudomonas sp. strain CF600 (Nordlund et al., 1990), Pseudomonas putida strain H (Herrmann et al., 1995), Pseudomonas putida F1 , Pseudomonas mendocina (Yen et al., 1991), Burkholderia cepacia G4 (Shields et al., 1989), Ralstonia pickettii (objective synonym of Pseudomonas pickettii) (Byrne et al., 1995) and Ralstonia eutropha (objective synonym of Alcaligenes eutrophus) (Kim et al., 1996). Methylosinus trichosporiumIn these organisms, TCE degradation is catalysed by monoxygenases or dioxygenases which are induced by specific substrates relevant to the enzymes. The inducers include various aromatic and aliphatic hydrocarbons such as toluene (Nelson et al., 1987), phenol (Folsom et al., 1990Harker & Kim, 1990), isopropylbenzene (Dabrock et al., 1992), propane and methane (Little et al., 1988 ;...

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Acetate conversion pathways of methanogenic consortia in acetate-fed chemostats at dilution rates of 0.025 and 0.6 day ؊1 were investigated by using 13 C-labeled acetates, followed by gas chromatography-mass spectrometry (GC-MS) analysis of the CH 4 and CO 2 produced. Nonaceticlastic syntrophic oxidation by acetate-oxidizing syntrophs and hydrogenotrophic methanogens was suggested to occupy a primary pathway (approximately 62 to 90%) in total methanogenesis at the low dilution rate. In contrast, aceticlastic cleavage of acetate by aceticlastic methanogens was suggested to occupy a primary pathway (approximately 95 to 99%) in total methanogenesis at the high dilution rate. Phylogenetic analyses of transcripts of the methyl coenzyme M reductase gene (mcrA) confirmed that a significant number of transcripts of the genera Methanoculleus (hydrogenotrophic methanogens) and Methanosarcina (aceticlastic methanogens) were present in the chemostats at the low and high dilution rates, respectively. The mcrA transcripts of the genus Methanosaeta (aceticlastic methanogens), which dominated the population in a previous study (T. Shigematsu, Y. Tang, H. Kawaguchi, K. Ninomiya, J. Kijima, T. Kobayashi, S. Morimura, and K. Kida, J. Biosci. Bioeng. 96:547-558, 2003), were poorly detected at both dilution rates due to the limited coverage of the primers used. These results demonstrated that the dilution rate could cause a shift in the primary pathway of acetate conversion to methane in acetate-fed chemostats.Under methanogenic conditions, acetate is quantitatively the most dominant intermediate of anaerobic degradation of organic matter. It is estimated that approximately 70 to 80% of methane is derived from acetate in anoxic environments (11,13,14). Two processes by which acetate is converted to methane have been described. The acetate-utilizing methanogens, the genera Methanosaeta and Methanosarcina, use the aceticlastic cleavage pathway in which the methyl group of acetate is converted to methane, while the carboxyl group is converted to CO 2 (4). The second process includes the syntrophic oxidation of acetate to CO 2 and hydrogen by one organism and the subsequent reduction of carbon dioxide to methane by a hydrogenotrophic methanogen. Two thermophilic bacteria, strain AOR and Thermacetogenium phaeum, and one mesophilic bacterium, Clostridium ultunense, were demonstrated to be capable of acetate oxidation in cocultures with hydrogenotrophic methanogens (7,10,19). The net reaction is the same as the reaction for aceticlastic cleavage of acetate in the syntrophic acetate oxidation process, but 14 C-labeled substrates have been used to differentiate between the two processes (16,18,24). The quantitative information for these two acetate conversion pathways in total methanogenic microbial communities has been limited to date.In a previous study, chemostat cultures of mesophilic acetate-degrading methanogenic consortia were constructed (8).The relative concentration of coenzyme F 420 , which is involved in hydrogenotrophic methanog...

Delftia tsuruhatensis sp. nov., a terephthalateassimilating bacterium isolated from activated sludge Terephthalate is an aromatic compound used in the production of polyethylene terephthalate (PET) and is one of the top 50 most abundantly manufactured chemicals in the world (Savostianoff, 1990). A large amount of terephthalate is discharged during production of PET bottles and purification of terephthalic acid. Biological degradation of this compound has therefore been of interest in recent years.Several micro-organisms have been shown to degrade terephthalate under aerobic conditions, including the Gram-positive bacteria Nocardia sp. strain DSM 43251 (Engelhardt et al., 1979), a Bacillus species (Karegoudar & Pujar, 1985) and Dietzia sp. strain GS-1 (Sugimori et al., 2000). Among the Proteobacteria, Bordetella sp. strain K1, Pseudomonas sp. strain C4S (Kimura & Ito, 2001) and two Comamonas testosteroni strains, T-2 (Schläfli et al., 1994) and YZW-D (Wang et al., 1995), have demonstrated the ability to degrade terephthalate.Most of these micro-organisms have been reported to produce protocatechuate as an intermediate metabolite.The enzymic system responsible for the degradation of terephthalate has been thoroughly studied for C. testosteroni strain T-2. In that strain, terephthalate is degraded to protocatechuate by the terephthalate 1,2-dioxygenase system (TERDOS) (Schläfli et al., 1994) and protocatechuate is then metabolized via the meta cleavage pathway. Another C. testosteroni strain, YZW-D, reportedly uses a similar enzyme system for degradation of terephthalate (Wang et al., 1995).Recently, a novel terephthalate-assimilating bacterium, designated strain T7 T , was isolated from the activated sludge of a domestic wastewater treatment plant. The isolate could utilize terephthalate as sole carbon and energy source. Based on 16S rRNA gene sequences and phylogenetic analyses, strain T7T was placed in the genus Delftia;Abbreviations: MLSS, mixed liquor suspended solids; PET, polyethylene terephthalate; TERDOS, terephthalate 1,2-dioxygenase system; TOC, total organic carbon.

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Production of a photosynthetic apparatus in Roseateles depolymerans 61A, a recently discovered freshwater ␤-Proteobacterium showing characteristics of aerobic phototrophic bacteria, was observed when the cells were subjected to a sudden decrease in carbon sources (e.g., when cells grown with 0.1 to 0.4% Casamino Acids were diluted or transferred into medium containing <0.04% Casamino Acids). Accumulation of bacteriochlorophyll (BChl) a was observed in the presence of oxygen and was enhanced under semiaerobic conditions (2% oxygen) but was reduced in the presence of light. Similarly to what has been reported regarding some aerobic phototrophic bacteria belonging to the ␣ subclass of the Proteobacteria, viability of the cells in the carbon source-free medium was prolonged under aerobic-light (10 W m ؊2 ) conditions, possibly due to photosynthetic energy conversion, but was not prolonged under aerobic-dark conditions. The puf operon, which encodes most of the apoproteins of light-harvesting and reaction center complexes, was sequenced, and the effect of changes in Casamino Acids concentrations, oxygen, and light on its expression was estimated by the accumulation of its mRNA. The expression of the puf operon was induced by the decrease in carbon sources, similarly to what was observed for the accumulation of BChl a under aerobic and semiaerobic conditions (>0.2% O 2 ), and was reduced in the presence of light. Transcription of the R. depolymerans puf operon is considered to be controlled by changes in carbon nutrients in addition to oxygen tension and light intensity.Purple phototrophic bacteria are taxonomically affiliated with the ␣, ␤, and ␥ subclasses of the class Proteobacteria. Many of the species grow both heterotrophically under aerobic-dark conditions and phototrophically under anaerobic-light conditions. The production of a photosynthetic apparatus in most of these phototrophic species is reduced under aerobic conditions (18). On the other hand, some species, the so-called aerobic phototrophic bacteria (e.g., Erythrobacter longus and Roseobacter denitrificans), do not grow phototrophically under anaerobic-light conditions, whereas they produce a photosynthetic apparatus under aerobic conditions (31, 41). Aerobic phototrophic bacteria had been reported only for the ␣ subclass of the Proteobacteria (31, 41) until the discovery of Roseateles depolymerans, which belongs to the ␤ subclass of the Proteobacteria (34).Although the presence of photochemical activity has been clarified in some species of aerobic phototrophic bacteria, they do not grow on light as a sole energy source (14,31,36,38). However, stimulation of growth in the presence of light has been reported for R. denitrificans, Erythromicrobium hydrolyticum, and Acidisphaera rubrifaciens (13,15,42). It has also been suggested for R. denitrificans, Bradyrhizobium strain BTAi 1, and A. rubrifaciens that the preservation of viability is improved by the presence of light in the absence of nutrients (9,15,29). While these observations have been reported f...