Quorum quenching specific genes screening among indigenous bacteria from full-scale membrane bioreactor and its application for biofouling control in a laboratory-scale membrane bioreactor

Present study isolated novel indigenous quorum quenching (QQ) bacterial species from a fullscale membrane bioreactor (MBR) treating real wastewater and applied in a laboratory-scale MBR for biofouling control. In the first phase, screening of the responsible QQ genes was performed by microbiological and molecular techniques. The QQ activity in the isolated strains was analyzed by biosensor based biochemical analysis. 16S rRNA sequencing yielded nine QQ species, the majority belonging to the genus Bacillus sp. and Enterobacter sp. Biochemical analysis for the QQ activity indicated higher acyl-homoserine lactones degradation ability by Pseudomonas sp. QSP01 (QS - quorum sensing) and Bacillus cereus sp. QSP03. In the second phase, the biofouling retardation potential of the Pseudomonas sp. QSP01 and Bacillus cereus sp. QSP03 was investigated in a laboratory-scale QQ MBR. The working volume of the reactor was 5 L with a 0.5% bead volume. The hollow fiber membrane of surface area 0.1 m(2) was operated at a flux of 15 LMH with a sludge retention time of 20 d and a hydraulic retention time of 4.16 h. Mixed liquor suspended solids of 5-6 g/L was maintained in MBR. The filtration cycle of Rhodococcus sp. BH4, QSP01 and QSP03 were found to be 15, 13, and 8 d, respectively.