Photolytic quorum quenching: A new anti-biofouling strategy for membrane bioreactors

Microbial quorum sensing induces biofilm formation on the membrane filter leading to severe biofouling. Here we show the novel observation and efficacy of long-wave UV photolysis as it interferes with microbial quorum sensing, particularly investigating anti-biofouling performances in membrane bioreactor systems. Continuous UV radiation significantly mitigated membrane biofouling, even more efficiently than bacterial quorum quenching achieved by the quorum quenching bacterium Rhodococcus sp. BH4. Intermittent UV photolysis had less quenching efficacy; it was, however, just as efficient as bacterial quorum quenching given an optimum UV dose. Indirect photolytic inactivation of signal molecules, such as acylhomoserine lactones and autoinducer-2, possibly occurred due to reactive oxygen radicals produced in the presence of nitrate ions. UV photolysis can be a new tool to inhibit microbial group behaviors (e.g., biofouling) occurring in membrane bioreactors and other biosystems.