Characteristics of β-glucosidase production by <i>Paecilomyces variotii</i> and its potential application in bioassay system for boric acid determination

Abstract

This study reports the potential application of Paecilomyces variotii immobilized in calcium alginate beads as a sensing element in the analysis of boric acid. In the presence of boric acid, β-glucosidase production of P. variotii was inhibited and the changes of β-glucosidase concentration were correlated to the concentrations of boric acid. The optimum conditions of β-glucosidase production were observed when 6% (w/v) mycelia of P. variotii was immobilized in 2% (w/v) sodium alginate with 0.25 M calcium chloride, at initial pH 7 and temperature 45°C. The response time of less than 3 h exhibited by P. variotii towards boric acid was observed. A linear response range of boric acid concentration was obtained within the range of 0.05 to 0.215% (w/v), with a detection limit of 0.037% (w/v). The immobilized cell beads were considered reproducible with the relative standard deviation (RSD) of 4.96 and 4.81% in the presence (0.2% w/v) and absence of boric acid, respectively. From the results, P. variotii could be beneficially useful towards developing an alternative approach for boric acid analysis.

Key words: Microbial bioassay, boric acid, Paecilomyces variotii, inhibition, β-glucosidase.