Glucoamylase is a widely used biocatalyst in food industry. Its major application is in the saccharification of partially processed starch to glucose. Filamentous fungi are traditionally employed to produce Glucoamylase. In the present study, the production of extracellular glucoamylase from Aspergillus niger SY1 was optimized under shake-flask conditions and characterized physico-chemically. The optimum temperature and initial medium pH for glucoamylase production were 30°C and 5.9 respectively. Glucoamylase production was noted in the presence of starch, glucose and maltose as sole carbon sources. Enzyme production was, however, affected by nitrogen sources, and maximal activity was attained in the presence of organic nitrogen source. The activity optima, using soluble starch as substrate, was pH 5.6 and 60oC. The enzyme activity was significantly increased in the presence of Mn2+ (10 mM) and K2+ (1 mM), while Ca2+, NH4+, Cu2+, Mg2+ and EDTA inhibited the activity to a certain extent. The presence of Urea crystals in increasing concentration up to 10 mM gradually improved the enzyme activity. The residual activity of the enzyme was lowered down to 50% after storage for ~3 hrs at 44°C - 60°C. The enzyme was found highly stable at pH ranged between 3.6 - 5.6 for upto 3 hrs. The enzyme, however, lost ~ 80% of its activity under alkaline conditions i.e. at pH ranged between 7.8 - 10.2 within 30 min of incubation. The hydrolysis products of starch analyzed by TLC demonstrated glucose as end product; confirming the character of the enzyme as glucoamylase.
Full conference title:
- ASM 115th (2015)