Screening Of Lipase Producing Alkalophiles Bacteria And Investigation Of The Properties Of Lipase

In this study, two alkalophiles bacteria strains producing lipase were isolated from soil with soybean oil as sole carbon source. They were indentified as Pseudomonas according to the 16S rDNA and blast in Genbank, named as Pseudomonas alcaliphila C-36 and Pseudomonas aeruginosa C-24, and their Genbank accession numbers are HM036359 and HM036358, respectively.The maximum lipase yield of 2.782 IU/ml for Pseudomonas alcaliphila C-36 was achieved under the optimized culture conditions, which are glycerol 2%(w/v), peptone 0.7%(w/v), yeast extract 0.5%(w/v), K2HPO40.2%(w/v), MgSO4·7H2O 0.5%(w/v), NaCl0.3%(w/v), TritonX-1000.01%(w/v), pH9.5,37℃,180r/minand24hincubation.Under the optimal fermental conditions, the fermental liquid of Pseudomonas alcaliphila C-36 was centrifugated and the supernatant was collected as crude enzyme. The partial purified lipase was achiveved through ammonium sμlphate precipitation, 10kD dialysis, DEAE-SepharoseCL-6B and Superdex 75 chromatography.The optimal temperature and pH of the lipase were 40℃and 9.0, respectively. The lipase is stable at pH range of pH7.5-9.5 and the half-time of the lipase at 50℃was 2 h. Among the eight tested metal ions, seven of the ions significantly increased the activity of lipase, whereas Zn2+ strongly inhibited the activity of lipase from Pseudomonas alcaliphila C-36. The lipase from Pseudomonas alcaliphila C-36 was found to be stable in organic solvents and substrates with medium carbon chain length seemed to be good substrates for the lipase from Pseudomonas alcaliphila C-36.In all, the screened strain Pseudomonas alcaliphila C-36 is a new alkaline bacterium producing lipase. The optimum pH at alkaline range and great stability in organic solvents are the desirable features for its future use in industry.