Paddy husk support for large scale solid state production and, extraction and stabilization of glucoamylase

Aims: Determination of the age of the mycelial inoculum is essential for the large-scale enzyme production. For small-scale cultivations of fungi, spore inoculum is generally used. Use of spore inoculum becomes difficult when large-scale cultivations are carried out and mycelia inocula become practically feasible. Similarly enzyme extraction in large-scale processes also makes it difficult to get higher yields of enzyme. Therefore this study was carried out. Methodology and results: Suitable age of the mycelial inoculum was 24 h and produced the highest glucoamylase activity (1735 U g / DS; Dry Substrate) on the 2nd day. When mouldy medium was used as inoculum, maximum glucoamylase produced in the first, second and third batches were 1205, 2101 and 1360 U / g DS (2nd day) respectively. Glucoamylase obtained by counter current extraction (100%) was the best among one- (33.5%), two- (42.9%) and three- (48.2%) step and counter current extraction procedures. When glucoamylase was diluted six times, the enzyme lost 41% of its activity initially during the first 24h and thereafter no significant loss of activity was observed up to 90 days. Glycerol of 5% (v/v) and above stabilized glucoamylase at 30 °C. Ammonium sulfate inhibited and decreased the stability of glucoamylase while addition of glycerol of different concentrations did not reverse the effect of ammonium sulfate on glucoamylase. Conclusion, significance and impact study: Suitable age of the mycelial inoculum was 24 h. Highest amount of glucoamylase was extracted by counter current extraction method. Glycerol concentration of 5% (v/v) and above stabilized the glucoamylase at 30 °C.