Improved amylolytic ability of Lactobacillus plantarum and Lactobacillus brevis strains isolated from Cassava mash and Ogi

Abstract

Lactic acid bacteria were investigated for their ability to degrade starch under various conditions. Three isolates were selected and they include two Lactobacillus plantarum strains and one Lactobacillus brevis (LP1, LP2 and LB respectively). Growth and amylase production were optimised with different carbon and nitrogen sources, pH, temperature, metal ions and starch concentrations. Obtained data were analyzed with the analysis of variance (ANOVA) using SPSS 2007. All the isolates gave the maximum values for growth and enzyme production at 30 ^oC while the optimum pH for growth was 5.0 for isolate LP2 and 6.0 for LB and LP1. The best pH for amylase production for the isolates was 6.0. Optimum amylase activity occurred at 50 ^oC for LP1 and LP2 and at 60^oC for LB. All the strains studied utilised all carbon sources for growth and amylase production. Concentrations of soluble starch affected amylase production considerably. Metal ions at low concentrations increased the activity of the enzyme while micromolar concentrations of EDTA and 2,4 DNP repressed the activity of the enzyme. LP1 and LP2 had the same V_max and K_max values of 5.0 while LB had the lowest values of V_max and K_max. LP1 had the highest K_m value.