Novel and Simple Method for the Instant Determination of Water Toxicity Based on an Early-Stage Biofilm of Electrochemically Active Bacteria

Water toxicity determination with electrochemically active bacteria (EAB) as an indicator holds great promise for early warning of water pollution. Previous studies mainly utilized a mature biofilm of mixed-cultured EAB, which requires several days to generate electricity, thus failing to provide instant determination of water toxicity. To solve this problem, this study establishes a novel and simple method by using an early-stage biofilm of pure-cultured EAB. Results demonstrated that an early-stage biofilm of Shewanella loihica PV-4 was prepared only by bacteria suspension filtering and generated an obvious electrical signal upon preparation. A sensor was designed for biofilm preparation and water toxicity determination. Metabolic substrates during toxic exposure obviously affected the sensitivity of toxicity determination, and the optimal parameters were 10.00 mM sodium lactate as the electron donor and 7.00 mM fumaric acid as the electron acceptor. The feasibility of the method was testified by using common heavy metals. This study provides a technical foundation for the instant and on-site determination of water toxicity.