title: Physiological and molecular characterization of anaerobic benzene-degrading mixed cultures.
abstract: Nine distinct anaerobic benzene-degrading cultures were enriched from sediment samples from four different sites. These cultures used nitrate, sulphate or CO2 as electron acceptors. The shortest doubling times were observed in nitrate-reducing cultures, although cell yield was lowest in these cultures. The highest substrate concentration utilized and maximum absolute rates of benzene degraded (in micro M day-1) were observed in methanogenic cultures. The microbial compositions of a methanogenic and nitrate-reducing culture were determined from a clone library of 16S rRNA genes. Five Bacterial 16S rRNA sequences, one of which resembled a clone previously found in a sulphate-reducing, benzene-degrading culture and four Archaeal 16S rRNA sequences were identified in a methanogenic culture. Four Bacterial and no Archaeal 16S rRNA sequences were identified in a nitrate-reducing culture. The relative abundance of the four nitrate-reducing putative species was determined by slot blot hybridization. Two green sulphur bacteria together formed 52% of the clone library, but were found to be less than 4% of the culture by slot blot analysis. One of the cloned 16S rRNA gene sequences comprised 70% of the culture and was phylogenetically 93% similar to both Azoarcus and Dechloromonas species, which have been shown to degrade aromatic compounds, including benzene, under nitrate-reducing conditions.
authors.affiliation: Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Ontario, M5S 3E5, Canada.
authors.forename: Ania C
authors.initials: AC
authors.lastname: Ulrich
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Edwards
mesh_terms: D000693:Anaerobiosis; D001105:Archaea / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D020627:Azoarcus / Q000235:genetics / Q000254:growth & development; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification; D001554:Benzene / Q000378:metabolism*; D001673:Biodegradation, Environmental; D003470:Culture Media; D004275:DNA, Ribosomal / Q000032:analysis; D017753:Ecosystem; D005618:Fresh Water / Q000382:microbiology*; D008697:Methane / Q000378:metabolism; D008969:Molecular Sequence Data; D009566:Nitrates / Q000378:metabolism; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology
chemical_list: D003470:Culture Media; D004275:DNA, Ribosomal; D009566:Nitrates; D012336:RNA, Ribosomal, 16S; D001554:Benzene; D008697:Methane