Living Reverse Osmosis Membranes to Prevent Biofouling and Reversing Methanogenesis to Capture Methane in Archaeal Biofilms

Membrane systems are being increasingly used for water treatment, recycling water from wastewater, during food processing, and energy production. They are thus a key technology to ensure water, energy and food sustainability. However, biofouling, the build-up of microbes and their polymeric matrix, clogs these systems and reduces their efficiency. Realizing that a microbial film is inevitable, we engineered a beneficial biofilm that prevents membrane biofouling by limiting its own thickness by sensing the number of its cells that are present via a quorum-sensing circuit (PNAS 113: E2802–E2811, 2016). The beneficial biofilm also prevents biofilm formation by deleterious bacteria by secreting nitric oxide, a general biofilm dispersal agent as demonstrated by both short-term dead-end filtration and long-term crossflow filtration tests. In addition, the beneficial biofilm was engineered to produce an epoxide hydrolase so that it efficiently removes the environmental pollutant epichlorohydrin. Thus, we have created a living biofouling-resistant membrane system that simultaneously reduces biofouling while providing a platform for biodegradation of persistent organic pollutants.