Production of extracellular amylase by Aspergillus niger under submerged fermentation using jack fruit rag as the carbon source

Weerasooriya, MKB ; Piyarathne, SAPM

Abstract

Production of extracellular amylase by Aspergillus niger was studied under submerged fermentation using jackfruit rag as the carbon source. Different parameters, such as incubation period, pH of the culture broth and level of substrate were changed to optimise the conditions for amylase production. Maximum enzyme production ~ 8400 units/g was obtained in 5 days old cultures, grown at pH, 6.5 and 30°C with substrate level 20 gL-1. As nitrogen sources NH4Cl, KNO3 casein, peptone and beef extract were tested. Except NH4Cl all other sources enhanced the amylase production. Study on the kinetics of extracellular and intracellular amylase production revealed that extracellular amylase production was always higher than that in intracellular. Crude amylase obtained from culture broth was partially purified by ammonium sulphate fractionation followed by DEAE Cellulose chromatography. Partially purified enzyme exhibited optimum pH and incubation temperature at pH 6 and 60°C respectively and higher thermal and pH stability at 50-60°C and pH 5-7 respectively and enhanced activity with Ca2+. These unique features of the enzyme indicates its suitability for various industrial applications. Shorter incubation period and lower substrate cost offer the potential for inexpensive production of amylase, making the process industrially and economically feasible.


Keyword(s)

Amylase; Aspergillus niger; Jackfruit rag; Submerged fermentation

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