Amylase Producing Bacteria from Ensete ventricosum (Welw) Cheesman (Ensete) and Their Abilities to Hydrolyse Starch in a Locally Designed Bioreactor

Abstract

Enset is a herbaceous perennial crop used as a basic diet for millions of people at various agro ecological settings of Ethiopia. As it takes up the nutrients from the soil environment, it makes mutual relation with rhizospheric microorganism which can contribute to the discovery of novel potential amylases producing bacteria. The bacteria isolated from enset are considered as an ideal source for the production of bulk extracellular amylase for industrial application. Therefore, starch degrading bacteria in starch rich enset using mini bioreactor was performed to isolate andcharacterize amylase producing bacterial strains. Amylase producing bacilli and Micrococcus species were identified. Based on biochemical tests, three isolates were confirmed as Bacillus badius, Bacillus licheniformis and Micrococcus varians. Effects of temperature, pH, and type of substrate on the activity of amylases producing bacteria were determined. All amylases produced by these isolates were able to hydrolyze starch after 48 hrs of fermentation. Bacillus licheniformis and Micrococcus varians were able to grow up to 50°C, whilst Bacillus badius was able to grow up to 80°C. Though, all isolates were able to grow from 4-9 pH values, the pH of 6 was found to be optimum for Bacillus badius, while pH of 7 was an optimum for remaining isolates. Findings from this research work has shown that bacterial isolates from Enset with thermophilic, and alkalophilic characteristics have wide range potential for industrial applications and need to be further optimized for efficient use.