Lipase production by Pseudomonas fluorescens (NRRL B-2641)

Lipase Production by Pseudomonas fluorescens (NRRL B-2641)In this study, the production of extracellular lipase by a gram (-) bacterium Pseudomonas fluorescens was studied in a batch system and the effects of system parameters on the production of lipase were investigated.In the first stage of the research; carbon and nitrogen sources and phosphate concentration used in synthetic fermentation medium were changed and the composition of the optimum enzyme production medium was determined. The highest activity was obtained at concentration of 1 % corn oil used as carbon sources. P.fluorescens showed better growth and higher activity in organic nitrogen sources. The highest activity was obtained in the fermentation medium containing 4 % peptone. Then, KH2PO4 and K2HPO4 concentrations in the fermentation medium were changed and the highest activity was obtained at 0.1 % KH2PO4 and K2HPO4. The effect of Ca2+ and Na+ ions were investigated. The enzyme activity increased in the fermentation medium containing 0.03 % CaCl2.2H2O. Maximum activity was determined as 3.425 U/mL in the optimized fermentation medium (corn oil 1 %, peptone 0.4 %, KH2PO4 0.1 %, K2HPO4 0.1 %, 0.0005 % MgSO4.7H2O, CaCl2.2H2O % 0.03).Waste oils such as fried potato oil and fried sweet oil were also used as carbon sources. The highest enzyme activities were obtained as 3.850 and 3.975 U/mL, for fried potato oil and fried sweet oil, respectively. This result indicates that waste fried oils are more effective substrates for lipase production than synthetic fermentation medium. Fatty acids in fermentation medium were also analyzed and it was observed that, fatty oil acids were consumed by P. fluorescens.In the second stage, sunflower seed meal was used as a solid state carbon source and lipase producibility of P.fluorescens was investigated. Maximum enzyme production (6.100 U/mL) was produced in the fermentation medium containing tap water, 10 % sunflower seed meal and 1 % peptone. The enzyme activity increased when sunflower seed meal was used as a natural substrate.In the last stage; enzyme activity, liquid phase volumetric mass transfer coefficients (kLa) and oxygen consumption rates (ro) at the different mixing and air flow rates were determined in 6 L laboratory-scale bioreactor. The highest activity was obtained as 2.350 U/mL in agitation speed of 350 rpm and air flow rate of 0.32 vvm. In this medium, the highest values of kLa and ro were found as 0.0423 s-, 0.0273 mg/L/s, respectively. Enzyme production increased with increasing air flow and stirred rates and transfer of oxygen were therefore found to be an important parameter of lipase production.