Screening, Isolation and Characterization of Amylase Producing Bacteria and Optimization for Production of Amylase

Abstract

The use of amylase enzyme has been extensive in different industrial sectors for quite a long time because of its various applications. In this study, soil from cassava processing site was screened for a bacteria with an amylase producing ability using starch iodine method and dinitrosalicyclic method. The biochemical and molecular characterization revealed the organism to be Bacillus circulan (CS2). Optimization of the enzyme production parameters was first carried out using the one factor at a time (OFAT) approach. The result obtained from OFAT study indicates that the following medium composition and culture conditions; medium pH 8, incubation temperature 45°C, incubation time 48 h, inoculum size 5%(w/v) of starch, lactose 1% (w/v), malt extract 1% (w/v), was suitable for the organism. Further optimization was done using Response Surface Methodology (RSM) based on Central Composite Design (CCD). RSM model was found to have a predicted R2and Adjusted R2value of -0.0666 and 0.3980 respectively and can significantly (p < 0.0500) predicted the response variables. Within the model interaction, effect between the model variables medium pH (A) and Lactose (D) were found to be significant. Optimal conditions for Amylase production by Bacillus circulans are Temperature of 35°C pH of 10 Lactose 1(%) and Malt Extract 2(%) which gave an enzyme activity of 15.776U/mL and biomass of 1.648. B.circulans was partially purified using ammonium sulphate and was also seen to be stable at temperature of 800C and a pH of 6.