Properties of Alpha-amylase of Lactobacillus plantarum Isolated from Cassava Waste Samples

Abstract

The search for various industrial enzymes including starch degrading enzymes has received a great deal of attention for their perceived technological and economic benefits. Alpha-amylase has been produced from large varieties of organisms including pathogenic ones which are not Generally Regarded as Safe (GRAS). In this study, a total of Thirty nine (39) lactic acid bacteria were isolated from the different cassava waste samples (peels, cassava waste water, fibre and soil). The isolates were screened for their ability to produce α-amylase on starch agar. The amylolytic activity of the selected isolates was determined using starch-iodine complex while the enzymes were characterized based on parameters such as pH, temperature, substrate concentration, and metal ions. Upon starch hydrolysis, 29.9% of the LAB isolates demonstrated amylolytic properties with L. plantarum having the highest occurrence. The selected amylase producer was identified both phenotypically and molecularly as L. plantarum S7. Enzyme production was found to be highest (10.573U/ml) at 30 hours of incubation. Optimum temperature and pH for the enzyme activity was found to be 40°C and 7 respectively. The α-amylase retained more than 50% of it residual activity at pH 7 and 8 after preincubation for 90mins. Calcium chloride (CaCl₂) and Ammonium disulphate (NH₄ (SO₄)₂) enhanced amylase activity however, the  activity was inhibited at 5mM molar concentration by KCl, BaCl₂, CuSO₄, NaCl, EDTA (10%) and Urea (10%). The genomic level confirmation was done with 16s rDNA and the sequence showed 90% sequence similarity with L. plantarum.