Screening And Classification For Cold-Adapted Lipase-Prodcucing Bacterium And Optimization Of Its Fermentation Conditions

Cold-adapted enzymes have recently received increasingly attention, due to their relevance for both basic and applied research. In the extreme environment of low-temperature and high pressure in Deep sea, there lives great quantity psychrotrophic and psychrophilic microorganisms, exploration of them will enrich Cold-adapted enzymes greatly.In this thesis, eight cold-adapted producing bacterium strains were screened from the mud of Parece Vela basin in Pacific Ocean of 5010m deep. Lipase production on agar medium was detected by the tributyrin diffusion plate assay. Strains D1 and D2 have the highest lipolytic activity in culture supernatent, great amounts lipase produced by remainder strains was located on the outer membrane of the cell envelope and was not released into the culture medium .The result of monoglyceride synthesis test showed the D2 lipase can synthesize monoglyceride.Factors affecting the D2 lipase production were investigated in shake flask level. Obtained result showed that the optimum medium composition and cultural condition were (%): beef extract 0.5 and NH4Cl 0.6 substitute YE extract and tryptone in 2216 culture medium respectively, 9℃,180r/min shaking ,for 40h,the pH of culture medium from 6-9 has little effect on lipase production .Under such conditions the lipase activity in culture supernatant was 4-5 times high as the original one. The result of orthorgonal test showed the nitrogen source is the important factor that influences lipase production. In addition, the lipase...