β-Glucosidase Production and Characterization of Some Aspergillus Strains

B. Flachner and K. Réczey

Abstract
Four Aspergillus strains, A. phoenicus ATCC1315B, A. niger BKM F-1305, A. foetidus Biogal 39 and A. phoenicis QM 329, were studied for β-glucosidase fermentation and compared with Trichoderma reesei RUT C-30. The enzyme productivity of Aspergilli was found to be 4.8 times higher than that of T. reesei. The fermentation supernatants were examined to find out the kinetical behavior of the non-purified enzyme because under industrial circumstances usually crude supernatant concentrates are used. Experiments were performed with p-nitrophenyl-β-D-glucopyranoside (p-NPG) the artificial substrate and cellobiose, the natural substrate of β-glucosidase. In the case of p-NPG substrate β-glucosidase follows substrate inhibition kinetics (at 1.5–2.0 mmol L–1) nevertheless in case of cellobiose substrate inhibition was not detected. The unpurified fermentation supernatants from all investigated Aspergillus strains are suitable to enzyme supplementation after concentration and its industrial usage may cut the cost of enzymatic hydrolyses of cellulose.

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Keywords
enzyme production, β-glucosidase, Aspergillus sp.