Induction of β-glucosidase in fungal and soil bacterial cultures

The production of β-glucosidase by soil enrichment cultures grown on cellobiose and carboxymethylcellulose and several experimental conditions were investigated in this work. The highest rates of induced enzyme activity were found in the soil cultures in which 0.4% cellobiose at pH 8.0 was used as the sole C and energy source. A bacterial strain, producing significant amounts of enzyme associated with the cell extracts and which was identified as Pseudomonas pickettii, was isolated from these soil cultures. In a comparative way, induction and location of β-glucosidase in Aspergillus niger cultures (using 0.4% cellobiose as C substrate) were also studied. In contrast with the results obtained with the bacterial cultures, only low levels of activity were detected when no N source was used. However, an appreciable amount of enzyme was assayed when 0.2% peptone was included in the culture medium with more than 70% of the total activity located in the extramycelial fraction.