Identification of hydrocarbon-degrading bacteria in soil by reverse sample genome probing

Bacteria with limited genomic cross-hybridization were isolated from soil contaminated with C5+, a mixture of hydrocarbons, and identified by partial 16S rRNA sequencing. Filters containing denatured genomic DNAs were used in a reverse sample genome probe (RSGP) procedure for analysis of the effect of an easily degradable compound (toluene) and a highly recalcitrant compound (dicyclopentadiene [DCPD]) on community composition. Hybridization with labeled total-community DNA isolated from soil exposed to toluene indicated enrichment of several Pseudomonas spp., which were subsequently found to be capable of toluene mineralization. Hybridization with labeled total-community DNA isolated from soil exposed to DCPD indicated enrichment of a Pseudomonas sp. or a Sphingomonas sp. These two bacteria appeared capable of producing oxygenated DCPD derivatives in the soil environment, but mineralization could not be shown. These results demonstrate that bacteria, which metabolize degradable or recalcitrant hydrocarbons, can be identified by the RSGP procedure.