Studies On Selective Breeding And Fermentation Conditions Of High-Yield Lipid Strain Produced In Yeast

Lipid is one of the basic material and life-sustaining activities, as well as important industrial raw materials, a broad application value. Currently fats resources mainly come from animal and plant, with about microbial lipid in-depth study, using microbial fermentation law was fats, not only will it ease the animal and plant fats scarce resources situation, and oil could be abandoned microbial resources of the use of resources for fats provided a new way.This paper is based on these points. Fatty acid can be produced by yeast ,one of microorganism, such as Lipomyces starkeyi(As2.1390), Lipomyces starkeyi(AS2.1560),Rhodotorula glutinis (As2.499),Rhodotorula mucilaginosa (As2.1515), Rhodosporidium toruloides(As2.1609), but the abilities produce fatty acid are different. In this paper, Lipomyces starkeyi(AS2.1560) is found to be a good strain to produce lipid. To increase its yield , Lipomyces starkeyi(AS2.1560), as an original strain, was mutated by UV and LiCl treatment. Mutant MLS24 was obtained after passing primary-screen and multiple-screen. The biomass 18.2 g/L and the total oil 10.8 g/L was obtained after 96 hours flask culturing of MLS24. These values are obvious higher than the original strain. After passing on many times, these were no distinct changes on the yield. Fermentation tests show that MLS24 has a capability to be improved to industrial strain.Then we studied several factors in the flask culture of MLS24.These factors included temperature, rotational speed, pH, inoculation amount, carbon sources, nitrogen sources, inorganic salts. The optimal shaking flask fermentation conditions were: glucose as carbon source at 110 g/L, (NH₄)₂SO₄ as nitrogen source at 0.09 g/L;KH₂PO₄3 g/L;MgSO₄ 1 g/L;CuSO₄0.2 μmol/L;ZnSO₄0.2 mmol/L; MnCl₂0.2μmol/L; initial pH of 5.0-7.0; inoculation volume of 15 %; temperature at 30 ℃; and culture volume of 50 ml in the 250 ml flask. Lipid productivity thus reached 15.6 g/L. The biomass was up to 26.7 g/L.