Utilization of shrimp shellfish waste as a substrate for solid-state cultivation of Aspergillus sp. S1-13: evaluation of a culture based on chitinase formation which is necessary for chitin-assimilation.

The utilization of shrimp shellfish waste as a substrate for solid-state cultivation of a filamentous fungus, Aspergillus sp. S1-13, was investigated. The organism was selected from among 220 isolates based on the productivity of its chitinolytic enzyme (chitinase), which might reflect microbial growth. The enzyme was produced only when the organism was grown on medium containing the shellfish waste. The addition of 58-65% water (w/w) to the medium was effective in enhancing production, and a certain amount of enzyme was observed in media of higher water content (up to about 75%). The initial pH and nitrogen source (ammonium sulfate) of the solid-state medium also affected the amount of enzyme. The amount of enzyme increased 2-fold in an optimum solid-state medium: 5 g of shrimp shellfish waste and 3 ml of basal medium (pH 5) containing 0.1% (NH4)2SO4 was inoculated with 4 ml of spore suspension; static cultivation at room temperature. The amount increased further (1.5-fold) when the cultivation was carried out at 37 degrees C, with 1.85 units of the enzyme formed from 1 g of shrimp shellfish waste. An analysis by ion-exchange column chromatography suggested the presence of at least two colloidal chitin-hydrolyzing enzymes and one p-nitrophenyl beta-D-N-acetylglucosaminide-hydrolyzing enzyme in an extract of the solid-state culture. The elution profile was similar to that obtained with a liquid culture filtrate.