Optimization of extracellular lipase production by thermotolerant bacteria isolated from a hot spring

Abstract

There is high demand for lipase globally where more than 1000 tons of it produced each year. A lipase produced from thermophilic bacteria is revised to have the advantage of thermal stability at 65°C-70°C, which makes them good candidates for lipid modifications which is most effective at high temperature. Thus, main focus of this research is to find the best lipase producing thermotolerant bacteria on its optimum condition of fermentation. The first step on finding lipase producer is to screen the isolated thermotolerant bacterial strains on tributyrin agar plate to check for zone of hydrolysis. Then, followed by screening under submerged fermentation. Next, lipase assay was carried out to find out the best lipase producer among the strains and finally the optimum condition for producing lipase investigated. Among four bacterial strains HS3 showed steady growth and clear zone of hydrolysis. During lipase assay process, HS2 proven to produce higher lipase activity compared to other strains. Therefore, this bacterial strain was chosen of the best lipase producer. During optimization four types of parameter was studied which is carbon source, nitrogen source, oil inducer and temperature. For each parameter there are four variables. Among carbon source Tween 80 proven to has produced highest lipase activity which is 0.09 U/ml. Peptone has shown highest lipase production among nitrogen sources by produced 0.11 U/ml. While from four oil inducers, olive oil strongly agreed to be the highest lipase producer with 0.11U/ml. Within the temperature range of 45-60°C, 55°C is the optimum temperature as it produced lipase activity of 0.09 U/ml. In conclusion, thermotolerant bacteria can produce lipase enzyme under optimum condition with suitable usage of carbon source, nitrogen source, oil inducer and temperature.