Effrcts Of Metalions On Lipid Production By Fermentation With Lipomyces Starkeyi

Effect of metal ions (Mg²⁺,Ca²⁺,Fe³⁺,Zn²⁺,Mn²⁺,Cu²⁺) on cell growth and lipid accumulation with Lipomyces starkeyi 1809 was investigated by fermentating in shaking flask. The relationship of different concentrations of Zn²⁺ and Mn²⁺ on cell growth and lipid synthesis was also studied. In addition, cell lipid fatty acid composition and relative content of fatty acid by six kinds of metal ions was clarified. The purpose of this paper was to provide reference and basis control for the microbial metabolism of fats and industrial fermentation.The main results were as follows:(1) When added different metal ions at different concentration , the variance of biomass, lipid yield, lipid content and lipid coefficient reached a significant level(P<0.01). Absence of Mg²⁺ or Fe³⁺ or Zn²⁺ in culture medium could significantly inhibited cell growth and lipid accumulation, whereas supplementing them at suitable concentration promoted cell growth and lipid accumulation. Supplementing Ca²⁺ or Cu²⁺ at proper concentration would facilitate cell growth and lipid biosynthesis. Absence of Mn²⁺ conduced to cell growth and lipid accumulation, the higher concentration of Mn²⁺ adverse lipid accumulation. Within the range of experimental concentration, the suitable concentration of metal ions for lipid accumulation were as follows: MgSO₄·7H₂O 1 000 mg/L, CaCl₂·2H₂O 500 mg/L, FeCl₃·6 H₂O 1.6 mg/L, ZnSO₄·7H₂O 0.3 mg/L, MnCl₂·4H₂O 0.008 mg/L, CuCl₂·2H₂O 0.08 mg/L.(2)A comprehensive test of two factors was carried out. It revealed that A4B2 was the most appropriate medium for oil production.A6B7 medium was not conducive to fat synthesis. In A4B2 medium, fermentation 120h, the oil yield, oil content and high fat content cells were 4.3 g / L, 43.7% and 1.25 mg/108cells respectively. The oleic acid and the palmitic acid comparative content are very high in the fatty acid composition,reached to 60.58% and 6.46% respectively.Next were the palmitoleic acid ,the linoleic acid and the stearic acid, the comparative content reached to 6.88%, 3.39% and 1.62% respectively.(3) It showed that in the L.starkeyi 1809 mycelium produced six kind of fatty acids, which were mainly C16 and the C18 series fatty acid. And the comparative content of palmitic acid (C16:0) and oleic acid (C18:1) occupies above 80% of the total fat, its composition was similar with the vegetable oil. The identical metallic ion's with different concentration had little affect to the mycelium fat fatty acid component, but can change the comparative content of the fatty acid and the degree of unsaturation actually. When the concentration of MgSO₄·7H₂O, CaCl₂·2H₂O, FeCl₃·6H₂O, ZnSO₄·7H₂O, MnCl₂·4H₂O and the CuCl₂·2H₂O was 2 000 mg/L, 100 mg/L, 3.2mg/L, 0 mg/L, 0.8 mg/L and 0.04 mg/L, IUFA was highest, reached to 69.87%, 69.00%, 71.15%, 72.15%, 71.39% and 71.79% respectively .