A Salt-Tolerant Yeast-Based Microbial Sensor for 24 Hour Community Wastewater Monitoring in Coastal Regions

Abstract.

A microbial sensor for rapid determination of the concentration of biodegradable pollutants in wastewater has been developed using the salt-tolerant yeast Arxula adeninivorans LS3 immobilized by gel entrapment with poly (carbamoyl) sulfonate hydrogel (PCS gel) on a Clark-type oxygen electrode. This sensor needs 5 min for every measurement instead of 5 days for BOD₅. The sensor has a linear response of up to 550 mg L⁻¹ BOD with a correlation of coefficient R² = 0.9785. The detection limit was calculated to be 2.1 mg L⁻¹ BOD equivalents, and the determination limit was 6.0 mg L⁻¹ BOD equivalents. The high tolerance to salt of the Arxula adeninivorans LS3 strain prevents the inactivation of cells caused by the seawater from affecting the measurements. In a 24-hour comparative study using real wastewater samples from an international college situated in Hong Kong, the microbial sensor showed a very good correlation (R² = 0.9134) with the standard BOD₅ method and truly reflected the ‘life cycle’ of the college people. The microbial sensor allows almost ideal real-time monitoring in water pollution and degradation.