The response of epilithic bacteria to different metals regime in two upland streams: assessed by conventional microbiological methods and PCR-DGGE

Abstract

The epilithic bacterial community in the zinc-contaminated River West Allen, northeast England, was compared to that in the less contaminated River East Allen. Bacterial abundance (DAPI counts) and activity (leucine assimilation rate) were similar in the two streams, suggesting the possibility that a tolerant community had developed in the West Allen. Despite the similarity in abundance and activity, molecular genomic methods (PCR-DGGE) showed that the epilithic bacterial communities were consistently different between the two streams, and that bacterial diversity was greater in the zinc-contaminated West Allen. Sequencing of DGGE bands indicated that α-Proteobacteria and Nitrospirae, previously associated with metal-rich environments, were present in the West Allen. This may support the suggestion that a metal-tolerant bacterial community had developed at the zinc-contaminated site.