BACKGROUND: Bacterial @entity349 resistance is based on enzymatic reduction of ionic @entity349 to elemental @entity349 and has recently been demonstrated to be applicable for industrial wastewater clean-up. The long-term monitoring of such biocatalyser systems requires a cultivation independent functional community profiling method targeting the key enzyme of the process, the merA gene coding for the @entity68949 . We report on the development of a profiling method for merA and its application to monitor changes in the functional diversity of the biofilm community of a technical scale biocatalyzer over 8 months of on-site operation. RESULTS: Based on an alignment of 30 merA sequences from Gram negative bacteria, conserved primers were designed for amplification of merA fragments with an optimized PCR protocol. The resulting amplicons of approximately 280 bp were separated by thermogradient gelelectrophoresis (TGGE), resulting in strain specific fingerprints for @entity349 resistant Gram negative isolates with different merA sequences. The merA profiling of the biofilm community from a technical biocatalyzer showed persistence of some and loss of other inoculum strains as well as the appearance of new bands, resulting in an overall increase of the functional diversity of the biofilm community. One predominant new band of the merA community profile was also detected in a biocatalyzer effluent isolate, which was identified as @entity796 . The isolated strain showed lower @entity349 reduction rates in liquid culture than the inoculum strains but was apparently highly competitive in the biofilm environment of the biocatalyzer where moderate @entity349 levels were prevailing. CONCLUSIONS: The merA profiling technique allowed to monitor the ongoing selection for better adapted strains during the operation of a biocatalyzer and to direct their subsequent isolation. In such a way, a predominant @entity349 reducing Ps. aeruginosa strain was identified by its unique @entity68949 gene.

Functional profiling of @entity68949 ( XXXX ) genes in biofilm communities of a technical scale biocatalyzer.

@entity349 :: ('MESH:D008628', 'Chemical') :: ['mercury'] @entity796 :: ('287', 'Species') :: ['Pseudomonas aeruginosa'] @entity68949 :: ('11372469', 'Gene') :: ['mercuric reductase']
@entity68949 :: (11372469,Gene) :: ['mer A']
