Graphene oxide/methyl anthranilate modified anti-biofouling membrane possesses dual functions of anti-adhesion and quorum quenching

Abstract

Biofouling has always been a persistent problem impeding the applications of membranes in water treatment. Quorum sensing (QS) inhibitors are able to interfere with bacterial cell-to-cell communication to alleviate membrane biofouling, among which, methyl anthranilate (MA) aims at disrupting the Pseudomonas quinolone signal (PQS)-mediated QS system to inhibit biofilm formation. In this study, we developed a novel anti-biofouling membrane via immobilizing MA on graphene oxide (GO) nanocarrier, which was then successfully coated onto a polyvinylidene fluoride (PVDF) membrane through layer-by-layer assembly method. The introduction of QS inhibitor MA suppressed the expression of PQS synthesis gene pqsABCDE, N-acyl homoserine lactones (AHL) synthesis gene lasI, rhamnolipid synthesis gene rhlA and PQS receptor gene pqsR, thereby mitigating biofilm formation on the modified membrane. GO on membrane surface contributed to the reduction of bacterial initial adhesion. The synergistic effect of GO and MA endowed the modified membrane with dual resistance to biofouling. Compared with the virgin membrane, the extracellular polymeric substances (EPS), ATP and total cell fluorescence on GO/MA-PVDF membrane (GO:MA = 1:3, 5 layers) were substantially reduced by 50%, 73% and 86%, respectively, illustrating its excellent anti-biofouling capability. Notably, the incorporation of GO/MA was still efficient when treating real secondary effluent, with the evidence of lower flux decline and restrained biofilm formation. Taken together, we believe that GO/MA-PVDF membrane with both anti-adhesion and anti-biofilm capability has broad prospects for biofouling control in water treatment.