title: Distribution and phylogeny of hexachlorocyclohexane-degrading bacteria in soils from Spain.
abstract: Hexachlorocyclohexane (HCH)-degrading bacteria are believed to mediate natural attenuation of HCH contamination and have potential for active bioremediation processes. This study addressed the very limited understanding of the distribution, diversity and substrate specificity of such bacteria from 13 soil samples, varying in levels of HCH contamination, from four sites in Spain. Hexachlorocyclohexane removal occurred in 16 of 36 enrichment cultures. Hexachlorocyclohexane-degrading populations were clearly associated with HCH-contaminated soils, and populations growing on the delta-HCH isomer were only found in soil contaminated with delta-HCH. beta-Hexachlorocyclohexane was persistent in enrichment cultures, and there was no evidence for populations growing on beta-HCH. From alpha- and gamma-HCH enrichment cultures, nine HCH-degrading isolates were obtained, which were all Sphingomonas spp. Attempts to isolate organisms from delta-HCH enrichment cultures failed. None of the isolates grew on HCH as a sole organic substrate in pure culture. All isolates degraded alpha- and gamma-HCH, and most degraded beta-HCH. delta-Hexachlorocyclohexane inhibited growth of most isolates, but could be degraded by cell suspensions of at least four strains. Denaturing gradient gel electrophoresis indicated that the isolates represented predominant populations in the enrichment cultures, but additional predominant populations, including some Pseudomonas spp., could not be isolated.
authors.affiliation: Department of Microbiology and Immunology, University of British Columbia, University Blvd., Vancouver, BC, V6T 1Z3, Canada. wmohn@interchange.ubc.ca
authors.forename: William W
authors.initials: WW
authors.lastname: Mohn
authors.forename: Birgit
authors.initials: B
authors.lastname: Mertens
authors.forename: Josh D
authors.initials: JD
authors.lastname: Neufeld
authors.forename: Willy
authors.initials: W
authors.lastname: Verstraete
authors.forename: Victor
authors.initials: V
authors.lastname: de Lorenzo
mesh_terms: D001483:Base Sequence; D001673:Biodegradation, Environmental; D016000:Cluster Analysis; D017931:DNA Primers; D004586:Electrophoresis; D001556:Hexachlorocyclohexane / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*; D013030:Spain; D013045:Species Specificity; D020578:Sphingomonas / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
chemical_list: D017931:DNA Primers; D012336:RNA, Ribosomal, 16S; D012989:Soil Pollutants; D001556:Hexachlorocyclohexane