Partial characterization and optimization of extracellular thermostable Ca²⁺ inhibited α-amylase production by Streptomyces erumpens MTCC 7317

Abstract

Culture parameters for optimum production of extracellular a-amylase by moderately thermostable Streptomyces erumpens MTCC 7317 isolated from a brick-kiln soil were found to be pH (6.0), temperature (50°C) and incubation period (36 h). Enzyme production was more in soluble starch (1%), beef extract (1%) and glycerol (0.02%) as compared to other carbon (1%: wheat flour, cassava starch, potato starch, cassava flour, etc.), nitrogen (1%: yeast extract, peptone, casein, ammonium chloride, etc.) and surfactant [0.02%: Cween (Tween) 20, Cween 40, Cween 60, Cween 80, sodium lauryl sulphate (SLS) and triton x 100] sources tested, respectively. Glycerol concentration (0.02 %) was most stimulatory in enzyme production. Addition of Ca²⁺ (even at 10 mM) inhibited a-amylase production. S. erumpens cells immobilized on sodium alginate beads produced more (9.0-23.4%) amylase as compared with free cells. Partially purified enzyme (by ammonium sulphate precipitation) had a molecular mass of 54,500 Da in native SDS-PAGE.