Synthesis of isopropyl-1-Thio-beta-D-glucopyranoside (IPTGlc), an inducer of Aspergillus niger B1 beta-glucosidase production

Production of beta-glucosidase in Aspergillus niger B1 is subjected to catabolic repression by glucose. Aspergillus niger B1 grown on bran as a carbon source secreted beta-glucosidase. The maximum level of the enzyme was reached after 7 d of fermentation. Addition of 1% glucose to the medium suppressed beta-glucosidase production to undetectable levels. In this study, the organic synthesis of a potential inducer of beta-glucosidase production by A. niger B1's reported. Isopropyl-1-thio-beta-D-glucopyranoside (IPTGlc) was synthesized using a two-step organic synthesis protocol. The H-NMR data agreed with those reported previously for the galactoside analog. When IPTGlc was added 24 h after inoculation at a final concentration of 0.4 mM, similar levels of beta-glucosidase were reached 3 to 4 d earlier as compared to fermentation without IPTGlc induction. In practice, this may translate to a more efficient method of producing beta-glucosidase from this fungus.