Microbial sensors for L-aspartic acid and urea

Abstract

L-Aspartic acid and urea sensors for bioprocess analysis were developed by coupling immobilized microorganisms to a sensing electrode. A microbial sensor for L-aspartic acid was developed by using Pseudomonas dacunhae membrane having L-aspartate β-decarboxylase activity immobilized with ϰ-carrageenan and a carbon dioxide electrode. The response was linear between 0.2 and 5 mM L-aspartic acid with slope of 50 mV/decade, and the response time was 5~15min. The sensor was stable for 70 d at 25°C, and selectivity was satisfactory. The results obtained by the sensor were in good agreement with those obtained by the conventional enzymatic method. A microbial sensor for urea was developed by coupling Sporosarcina ureae membrane having urease activity immobilized with ϰ-carrageenan to an ammonia-gas electrode. The sensor showed a linear range of 0.1 to 50 mM urea with a slope of 55 mV/decade. The sensor was stable for 30 d at 25°C and kept the selectivity. The accuracy of the results obtained by the sensor was higher than that by the conventional colorimetric method. Both sensors were found to be useful as a simple, economical and selective method for the determination of L-aspartic acid and urea in bioprocess analysis. © 1990, The Japan Society for Analytical Chemistry. All rights reserved.