Characterization of renninlike enzyme produced in submerged culture of aspergillus niger

ABSTRACT

Aspergillus migor produced powerful milk - clotting activity when it was grown aerobically in submerged cultures. The enzyme could be produced in sweet rennet buffalo whey and in salted whey media without extraneous- supplementation with other nutrients. Characterization studies on the activity produced in sweet whey media have revealed that the enzyme activity responded to dilution in a linear mainner, thus permitting the prio adjustment of the milkclotting time as desired. The addition of calcium chloride increased the milk-clotting activity many folds up to 0.081T a3 final concentration, whereas the incorporation of sodium chloride in the reaction mixture resulted in significant inhibition of the clotting reaction particularly at high concentrations. The enzyme was heat-tolerant up to 60. On the other hand, the milk-clotting reaction catalyzed by this enzyme had an optimum temperature range between 70§ to 80§, thus, suggesting, possible activity protection by the presence of the substrate. The results obtained are discussed in the light of the application feasibility of this eyzyme as a substitute for animal rennet