RECOVERY OF ASPERGILLUS ENDO-GLUCANASE PRODUCED ON SOLID SUBSTRATE: A DOE BASED APPROACH

Abstract

The endo-glucanase (E.C. 3.2.1.4) was produced by Aspergillus terreus adopting solid state fermentation (SSF) using agro residues as main substrate. To recover the enzyme from the fermented mass, different extraction liquids were tried and 10% aqueous solution of glycerol was found to be superior. When the selected extractant was applied at different ratio to the fermented solid mass, maximum enzyme was recovered at 1:5 (w/v) ratio. The other process parameters (time, temperature and mixing speed) effects on the enzyme recovery were subsequently studied by response surface methodology (RSM). Box-Bhenken Design of experiment (BBDOE) was exploited for the analysis of interactive effects of the independent variables. The optimization was done following the numerical approach focusing reduction in utility cost without compromising the endo-glucanse activity. Based on the predicted solution the validation experiments were carried out and finally 32 IU/g of endo-glucanase was recovered at room temperature, at a mixing speed of 100 rpm in 2.65 h which was very close to the predicted response. The optimization evidenced more than two times betterment in enzyme recovery than the un-optimized state. The model developed was found to be robust for process analysis. Repetitive extraction had revealed that maximum endo-glucanase recovery was required of two cycles of extraction at optimized conditions.