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 60oC 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 Vmax and Kmax values of 5.0 while LB had the lowest values of Vmax and Kmax. LP1 had the highest Km value.