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Identification and quantification of uncultivated Proteobacteria associated with pyrene degradation in a bioreactor treating PAH‐contaminated soil
Author(s) -
Singleton David R.,
Sangaiah Ramiah,
Gold Avram,
Ball Louise M.,
Aitken Michael D.
Publication year - 2006
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/j.1462-2920.2006.01112.x
Subject(s) - sphingomonas , pyrene , 16s ribosomal rna , biology , proteobacteria , library , bioreactor , microbiology and biotechnology , stable isotope probing , bacteria , ribosomal rna , environmental chemistry , food science , gene , botany , biochemistry , chemistry , genetics , microorganism , astrobiology
Summary Uncultivated bacteria associated with the degradation of pyrene in a bioreactor treating soil contaminated with polycyclic aromatic hydrocarbons (PAH) were identified by DNA‐based stable‐isotope probing (SIP) and quantified by real‐time quantitative PCR. Most of the 16S rRNA gene sequences recovered from 13 C‐enriched DNA fractions clustered phylogenetically within three separate groups of β‐ and γ‐Proteobacteria unassociated with described genera and were designated ‘Pyrene Groups 1, 2 and 3’. One recovered sequence was associated with the Sphingomonas genus. Pyrene Groups 1 and 3 were present in very low numbers in the bioreactor but represented 75% and 7%, respectively, of the sequences recovered from 16S rRNA gene clone libraries constructed from 13 C‐enriched DNA. In a parallel time‐course incubation with unlabelled pyrene, there was between a 2‐ and 4‐order‐of‐magnitude increase in the abundance of 16S rRNA genes from Pyrene groups 1 and 3 and from targeted Sphingomonas spp. over a 10 day incubation. Sequences from Pyrene Group 2 were 11% of the SIP clone libraries but accounted for 14% of the total bacterial 16S rRNA genes in the bioreactor community. However, the abundance of this group did not increase significantly in response to pyrene disappearance. These data indicate that the primary pyrene degraders in the bioreactor were uncultivated, low‐abundance β‐ and γ‐Proteobacteria not previously associated with pyrene degradation.