Optimization of an extracellular protease of Chrysosporium keratinophilum and its potential in bioremediation of keratinic wastes.

Chrysosporium keratinophilum IMI 338142 isolated from a waste site containing organopollutants was studied for its ability to produce extracellular proteases on glucose-gelatin medium. Fungus was observed to be a potent producer of such enzymes. Enzyme secretion was best at 15 days of incubation period at pH 8 and temperature 40 degrees C. Asparagine was repressive to protease expression. No relationship existed between the enzyme yield and increase in biomass. Exogenous sugars suppressed enzyme production in the descending order as follows: glucose > arabinose > maltose > mannose > fructose. The enzyme released showed the ability to decompose two keratin substrates tested. Buffalo skin was the most actively degraded substrate when exogenous glucose was absent. Presence of glucose suppressed both enzyme production and degradation of keratin. However, the rate of keratin degradation was independent of enzyme production.