Primary Study On Breeding Of Microorganism Of Lipase And Its Application To Biodiesel

The depleting of fossil fuel resources and the increasing environmental problem induced by fossil fuel resources are the driving force for the industry to develop clean and renewable fuels.Biodiesel receives increasing attention as an alternative,non-toxic,and renewable diesel fuel.Production of biodiesel catalyzed by lipase has more advantages compared with.chemical catalysts,which is gaining more and more attention.Breeding of microorganism producing high-activity lipase,optimization of fermentation condition and process on the castor oil to biodiesel catalyzed by lipase has been mainly studied in this paper.The results were listed as follow:Through a series of steps including plate isolation using castor oil as sole carbon source,flask fermentation and detection of transesterification activity to catalyze the production of biodiesel,one strain which named H-4 to produce lipase and effectively catalyze the transesterification of castor oil to biodiesel was selected from soil of castor planting.The H-4 strain was identified as Pseudomonas sp.according to morphological observation.The properties of enzyme of this H-4 lipase were also being studied.The result showed that the optimum pH was 8.0 and the optimum temperature was 40℃.The results of optimized flask fermentation condition of H-4 lipase were as follows: 0.6%sucrose,1.5%soybean power,0.3%(NH₄)₂SO₄,0.1%sodium citrate,0.02% MgSO₄·7H₂O,0.4%K₂HPO₄,0.6%KH₂PO₄.The final enzyme activity reached 114 IU/mL when the inoculated medium was cultivated at 30℃,220r/min of rotation speed,50mL medium in 250mL flask,5%inoculation volume and 60h of culture time.The process of the H-4 lipase catalyzed the transesterification of castor oil to biodiesel was optimized.The result showed that 85%of transesterification degree was reached under the optimal reaction conditions the dosage of methyl alcohol and castor oil were 1.092g and 3.408g(the molar ration of methyl alcohol to oil was 3:1),the time of pretreatment was 7 min when the 6000r/min rotation speed,the times of adding the methyl alcohol was 3,the dosage of lipase was 0.65g(by the weight of the castor oil),reaction temperature was 42℃, the rotation speed was 150r/min,and the time of the whole reaction was 9.5h.