[Isolation of Quorum Quenching Bacteria and Their Function for Controlling Membrane Biofouling]

Interspecies quorum quenching by bacterial cells has been reported as a novel approach for mitigating the biofouling via restraining quorum sensing(QS). Five indigenous quorum quenching bacterial strains were isolated from activated sludge taken from wastewater treatment plant. Strain HG10 showed high degrading activity against C6-HSL(N-hexanoyl-L-Homoserine lactone). The result of 16S rDNA sequencing showed that the isolated strain HG10 belonged to the genus Bacillus cereus. Strain HG10 was immobilized in sodium alginate(SA), and the biofouling inhibition of SA-HG10 in membrane filtration treatment system was investigated. The results showed that the membrane flux in experimental group B(provided with SA-HG10)was 181.29 L·(m²·h)^-1, and the membrane flux in control group A (without the beads) was 110.64 L·(m²·h)^-1, The membrane flux in group B was 63.86% higher than group A. The content of extracellular polymeric substances (EPS) in the biofilm on the membrane filter was also measured. The results showed that the contents of polysaccharides and proteins in the experimental group B decreased by 29% and 48% respectively than those of group A. A large decrease in the content of hydrophobic proteins was the main reason for the decrease of membrane fouling. The content of EPS in the membrane surface decreased by 43%, indicating that SA-HG10 could inhibit biofilm formation on the membrane filter and effectively improve the filtering performance.