Arxula adeninivorans LS3 as suitable biosensor for measurements of biodegradable substances in salt water

A microbial amperometric sensor based on the yeast Arxula adeninivorans was tested to determine its suitability for measuring biochemical oxygen deman d (BOD) in salt water. The viability of cells immobilized onto the sensor m embrane was hardly influenced up to 10% (w/v) NaCl in the sample, although the solubility of oxygen was affected. NaCl concentrations higher than 10% (w/v) caused a marked decrease in the oxygen solubility and deactivated the sensor. This outcome depended on the substrates used, e.g., alanine-, gala ctose- and acetic acid-sensor signals were influenced by any salt concentra tion whereas glucose-, glycerol-, maltose- and arginine-sensor signals were influenced only by higher salt concentrations. Sensor signals from yeast e xtract as well as glucose correlated with the quantity of these substances and with the salt concentration contained in the water. This correlation wa s linear up to 10% (w/v) NaCl and 0.125% (w/v) yeast extract or up to 10% ( w/v) NaCl and 0.125% (w/v) glucose in the sample. The sensor signals are th erefore influenced only by NaCl-determined solubility of oxygen and not by the physiological parameters of the immobilized cells. However, an increase of yeast extract- or glucose-concentrations in the presence of NaCl caused physiological effects on the sensor cells. (C) 1998 Society of Chemical In dustry.