Synergistic Treatment of Reverse Osmosis Membrane Biofouling with Quorum Quenching Bacteria and Hitchhiking Phages

Biofilm formation, which is facilitated by quorum sensing (QS), significantly impairs the performance of pressure-driven membrane systems in water treatment. Herein, we present a quorum quenching (QQ)-phage phoresy system to control biofouling by disrupting QS-mediated interactions. This system, which is composed of the QQ bacterium <i>Paenarthrobacter nicotinovorans</i> as carriers and hitchhiking lytic phages infecting <i>Pseudomonas aeruginosa</i> with active QS systems, significantly decreased QS signal levels, inhibited the extracellular polymeric substance (EPS), and reduced bacterial abundance in mature biofilms. Transcriptomic analysis revealed that phage treatment upregulated QS and EPS synthesis genes in <i>P. aeruginosa</i>, but the QQ bacteria downregulated QS-related genes, weakening the bacterial EPS secretion and antiviral systems and facilitating phages to infect and lyse the target bacteria. Metabolomic profiling corroborated that the phoresy system disrupted pathways critical to biofilm stability, including the tricarboxylic acid cycle, carbohydrate metabolism, and amino acid metabolism. In off-site membrane cleaning experiments, the phoresy system promoted <i>P. nicotinovorans</i> colonization and replaced the niche of <i>P. aeruginosa</i> on the membrane surface, which restored membrane flux (i.e., 90% recovery in severely biofouling systems). Operation studies showed that the phoresy system reduced fouling rates, extended the membrane lifespan, and maintained salt rejection performance for reverse osmosis (RO) membrane systems. These findings highlight the potential of the QQ bacterium-phage system as a sustainable alternative to conventional chemical treatments that damage polymeric membranes.