New method for rapidly screening sulfate-reducing bacteria in activated sludge

The common way for screening sulfate-reducing bacteria (SRB) from activated sludge is inaccurate, time-and labor-consuming due to the high biodiversity and phylogenetic decentralization of this kind of anaerobe. And 16S ribosomal RNA gene (rDNA) sequencing directly is unsuited to screen SRB out substantive bacteria in view of its cost. In this study, a novel method based on gradient PCR was developed using SRB-specific 16S rDNA primer SRB385F as forward primer and eubacterial universal primer EUB926R as the reverse primer. An improved annealing temperature was found which would amplify the 16S rDNA of the bacteria isolated on SRB universal culture media. Compared the amplified band with positive and negative controls, it can be determined whether the isolates are SRB or not. The procedure requires only about 6 hours. Subsequently, it is demonstrated that all positive strains are SRB via the 16S rDNA sequences determined.