Synthesis of lsopropyl-1-thio-β--D-glucopyranoside (IPTGlc), an inducer of aspergillus niger B1 β-glucosidase production

Production of β-glucosidase in Aspergillus niger B1 is subjected to catabolic repression by glucose. Aspergillus niger B1 grown on bran as a carbon source secreted β-glucosidase. The maximum level of the enzyme was reached after 7 d of fermentation. Addition of 1% glucose to the medium suppressed β-glucosidase production to undetectable levels. In this study, the organic synthesis of a potential inducer of β-glucosidase production by A. niger B1's reported. Isopropyl-1-thio-β-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 β-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 β-glucosidase from this fungus.