Abstract
Stachybotrys microspora is a filamentous fungus characterized by the secretion of multiple β-glucosidases. The production of these enzymes was studied under culture with variable carbon sources. The highest activity was produced on glucose (0.66 U ml−1) whereas galactose, lactose, cellobiose, Avicel cellulose, carboxymethylcellulose (CMC), wheat bran and gruel allowed intermediate production levels ranging between 0.08 and 0.48 U ml−1. The zymogram analysis showed that complex sugars such as Avicel cellulose and CMC induced the expression of several β-glucosidases whereas all tested simple sugars (mono and disaccharides) induced the expression of one single β-glucosidase, each time different. The most efficient β-glucosidase named bglG was produced on glucose which continues to be, at the same time, its strong inhibitor. The bglG N-terminal sequence confirmed that it is a novel β-glucosidase. According to its large molecular weight, this enzyme was assumed to belong to family 3 of β-glucosidases. RT-PCR analysis showed that family 3 expressions were induced on glucose while those of family 1 were repressed. Finally, with the use of different combinations of glucose and various carbon sources at different ratio, we showed that such sources direct the differential expression of β-glucosidases in S. microspora since our strain co-produced the β-glucosidases corresponding to each carbon source.
Published Version
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