Bacterial Cellulose Immobilized S. cerevisiae as Microbial Sensor for Rapid BOD Detection

As one of the most important parameters to characterize the organic pollution of water, biochemical oxygen demand (BOD) determined through a rapid, in situ and on line method is very attractive. In this paper, a new BOD biosensor has been developed, which are composed of the ecofriendly precursor of Saccharomyces cerevisiae ( S. cerevisiae ) embedded in bacterial cellulose (BC) matrix and the Ketjen Black (KB) modified glassy-carbon electrode. Furthermore, a doublemediator system is constructed using potassium ferricyanide and menadione in reaction cell to transfer electron from the microbe to electrode. The responses of glucose glutamic acid (GGA) standard solutions are amperomertrically measured with an applied potential of 0.25 V versus Hg/Hg 2 Cl 2 in a three-electrode system. Under the optimum conditions, the (BC/ S. cerevisiae -menadione)/KB modified electrode shows a high operational stability with relative standard deviation (RSD) of 4.16% (fourteen assays), a good repeatability (RSD=3.10%), a fast response time (in 20 minutes) and a wide linear range (from 10–220 mg O 2 l −1 ). The BOD values measured by this method have been highly correlated with the standard BOD 5-day method for wastewater samples (R 2 =0.9859, n=3), indicating that it can meet the requirement of BOD rapid measurement.