Investigation of lipase production by milk isolate Serratia rubidaea

Production of extracellular lipase in submerged culture of Serratia rubidaea has been investigated. The lipase production was optimized in shake flask experiments. The observed pH and temperature range optimum for maximum lipase production were 7-8 and 30-40 degree C, respectively. With a selected nitrogen source, casein ((6.5 plus or minus 0.015) U/mL) and soytone ((9.4 plus or minus 0.02) U/mL) were suitable substrates for accelerating lipase production. The optimized concentration of casein and soytone was 24 g/L ((9.95 plus or minus 0.02) U/mL) and 5 g/L ((14.8 plus or minus 0.03) U/mL), respectively. The effect of carbon source on lipase production indicated that starch was suitable substrate to maximize lipase production ((15.60 plus or minus 0.20) U/mL) and the optimum concentration registered was 4 g/L ((17.46 plus or minus 0.20) U/mL). Investigating the effect of lipids and surfactants showed that the gingily oil ((20.52 plus or minus 0.20) U/mL) and Tween 20 ((27.10 plus or minus 0.01) U/mL) were suitable substrates for maximizing lipase production, and the optimum concentrations registered were 15 mL/L ((23.15 plus or minus 0.24) U/mL) and 6 mL/L ((34.20 plus or minus 0.01) U/mL), respectively. Partial purification of lipase indicated that the molecular mass of partially purified enzyme was 54 kDa.