Mediated microbial biosensor using a novel yeast strain for wastewater BODmeasurement

Two new yeast strains (SPT1 and SPT2) were isolated and immobilized on glas sy carbon electrodes to form microbial biosensors for estimation of biochem ical oxygen demand (BOD). Ferricyanide was proven to be the most efficient mediator to shuttle electrons from the redox center of reduced microbial en zymes to the electrode in the presence of excess glucose/glutamic acid (GGA ). With a 3-fold greater metabolic assimilation capability and greater resp onses to various effluent samples, SPT1 was selected for sensor-BOD measure ments. BOD estimations for the GGA standard resulted in an extended linear range: 2-100 mg/l. Response reproducibility was +/- 10% for a GGA standard containing 10 mg BOD/l. For analysis of pulp mill effluents, the BOD detect ion limit was 2 mg/l with a response time of 5 min.