Characteristics of β-glucosidase production by Paecilomyces variotii 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.