Production of extracellular protease by Aspergillus tamarii

The production of protease by Aspergillus tamarii was investigated in submerged fermentation using different substrates. Low basal proteolytic activity was detected on cultures with casein or gelatin as the only substrate (16–20 U/ml). The enrichment of protein medium with glucose increased the protease production up to 6 times (110 U/ml). The highest proteolytic levels were obtained in cultures supplemented with wheat bran (120 U/ml) and soybean meal (161 U/ml). One major proteolytic band with estimated molecular mass of 48 KDa was detected by SDS‐PAGE. The acetone‐precipitated enzyme was active and stable over a wide range of pH (6–9.5), and temperature (30–55 °C). The enzyme was stable for more than ten hours at temperatures up to 45 °C. The half‐lives at 50 and 55 °C were 90 min and 12 min, respectively. In presence of 5.0 mM CaCl₂, the half‐life of the enzyme at 55 °C was increased to 130 min.