A technique for inhibiting biofouling caused by biofilms grown on a material surface of a water system where microorganisms exist such as the membrane surface of a membrane bioreactor (MBR) for advanced wastewater treatment is disclosed. Specifically, a magnetic carrier comprising an enzyme for quenching quorum sensing that inhibits biofilm formation, a membrane bioreactor system that can be stably operated without inactivation and loss of enzymes and a method for inhibiting biofilm formation are described.