Optimization of amylase and lipase enzymes produced by Bacillus cereus and Bacillus subtilis isolated from waste dumpsites

Abstract

The enzyme amylase is one of the most important in biotechnology, and lipase operates as a catalytic agent for a broad range of hydrolytic and synthetic activities. This study aimed to assess the optimization of amylase and lipase enzyme produced by microorganisms isolated from selected waste or garbage dumpsite in Akure, Ondo State Nigeria. The isolates were identified using biochemical and cultural characteristics. A total of seven bacterial isolates were identified and quantitative production of amylase and lipase by solid-state fermentation was assessed for each bacterial isolate. The optimization of nutritional and environmental parameters on enzymes produced by the isolated organisms was standardized with respect to incubation time, temperature, pH, and carbon and nitrogen sources. The activity of the enzymes generated was determined by spectrophotometric assay. Of the seven organisms isolated, Bacillus cereus LA326 and Bacillus subtilis AU021 had the highest amylase and lipase activity and were therefore chosen for further research. The maximum level of amylase and lipase activity attained by B. subtilis AU021 was 68.0 mmol/min and 16.3 mmol/min after 18 hours of incubation respectively, while the maximum levels of amylase and lipase activity attained by B. cereus LA326 were found to be 76 mmol/min after 12 hours and 16.3mmol/min after 18 hours of incubation, respectively. The study found that B. cereus and B. subtilis isolated from dumpsites could be efficient producers of biotechnology-relevant enzymes and that environmental conditions could influence their enzyme production.