Studies On Culture Medium And Fermentation Condition For Lipid Producing By Sporobolomyces Reseus Utilizing Sweet Potato Starch Hydrolysates

ABSTRACT: Lipid is one of the basic material for life-sustaining activities and important industrial materials. As lipid resources mainly come from the animal and the plant, the problem of lipid lack is encountered at times. The lipid from microorganisms is the substitute and superior to the above lipid with a short period of production and much cheaper fermentation materials such as agricultural and sideline products or wastes of crop.Thus large scale production and broad application of microbial lipid will be efficient not only in substitute of the animal and the plant lipid for food and industrial field, but also inducing a new way leading to solve the energy problem.For the purpose of exploring the characteristics of lipid production of red yeasts from sweet potato starch hydrolysates. 19 red yeasts are screened for the capability of lipid producing and one strain Sporobolomyces reseus As.2.618 with superior performance is sellected.To improve the Sporobolomyces reseus As.2.618s capability of lipid accumulation, the components of the medium, which may influence the growth of the strain and the lipid yield have been studied. To get the optimum medium components, the "uniform design" was used. The DPS software gave the optimum medium component is: reducing sugar 103 g/L,yeast extract 11.5 g/L,KH₂PO₄ 0.3g/L, MgSO4 0.15 g/L. The biomass could reach up to 19.23 g/L and lipid yield 3.87 g/L with the above composition of fermentation medium. Furthermore the fermentation conditions, addition of the divalent metal ions and the oxygen vector to increase the strain's lipid producing capability are tested. The optimum condition is: reducing sugar 103 g/L,yeast extract 11.5 g/L,KH₂PO₄0.3 g/L,MgSO₄ 0.15 g/L, Adding 30mg/L ZnSO₄, and adding 2g/L CaCO₃ 2%(v/v) n-dodecane after 24h's fermentation, the optimal fermentation condition were as follow: 30ml medium in the 500ml flask with initial pH 6.0, the flasks with 5% inoculation volume were at 200r/rain shaking speed for 7d's fermentation at 27℃. Under this kind of condition the high biomass which reach to 35.05 g/L could be got, the yield of lipid also could reach to 11.98g/L.