Biofouling Control in an Anaerobic Membrane Bioreactor with Indigenous Quorum Quenching Bacterium Micrococcus luteus Strain AnQ-m1

Abstract

This study isolated and screened indigenous strains quenching the acyl homoserine lactone (AHL)-mediated quorum sensing system and investigated the effectiveness of a selected strain for biofouling control in a laboratory-scale anaerobic membrane bioreactor (AnMBR). Among the 11 facultative anaerobes isolated from anaerobic sludge, Micrococcus luteus strain AnQ-m1 was screened out as the most potent AHL degrader. Its AHL degradability was further examined while encapsulating the cells in polysulfone–alginate beads to optimize the encapsulation medium recipe. The QQ beads with immobilized AnQ-m1 cells retarded the apparent membrane fouling rate by 2.2 times compared with the AnMBR with vacant beads. C8-HSL, the dominant AHL in AnMBRs, was effectively (∼70%) quenched in the QQ-AnMBR before the membrane was fouled; however, its concentration was increased to the normal level when the membrane was fouled. Polysaccharides in a loosely bound extracellular polymeric substance were gradually reduced at a constant rate during the QQ stage, while the indigenous QQ strain barely affected the microbial community structure of the bulk sludge and the water treatment performance of the AnMBR. These findings provide new insights into the QQ-based biofouling control strategy and highlight the beneficial effects of indigenous QQ strains on AnMBR stability.