Purification and biochemical characterization of extracellular glucoamylase from Paenibacillus amylolyticus strain

In the present study, glucoamylase produced from a soil bacterium Paenibacillus amylolyticus NEO03 was cultured under submerged fermentation conditions. The extracellular enzyme was purified by starch adsorption chromatography and further by gel filtration, with 2.73-fold and recovery of 40.02%. The protein exhibited molecular mass of ∼66,000 Da as estimated by SDS–PAGE and depicted to be a monomer. The enzyme demonstrated optimum activity at pH range 6.0–7.0 and temperature range 30–40 °C. Glucoamylase was mostly activated by Mn 2+ metal ions and depicted no dependency on Ca 2+ ions. The enzyme preferentially hydrolyzed all the starch substrates. High substrate specificity was demonstrated towards soluble starch and kinetic values K m and V max were 2.84 mg/ml and 239.2 U/ml, respectively. The products of hydrolysis of soluble starch were detected by thin layer chromatography which showed only D -glucose, indicating a true glucoamylase. The secreted glucoamylase from P. amylolyticus strain possesses properties suitable for saccharification processes such as biofuel production.