Abstract:
The effect of temperature and zinc ion on fatty acid composition, totalfatty acid and gamma linolenic acid (GLA) content in Mucor rouxii ATCC 24905 werestudied. The experiments were performed at 10 C!, 15 C , 25 C and 30 C in anincubator shaker at 130 rpm. The highest growth was obtained at 30 C. Furthermore,the temperature regulated total fatty acid production (%,g-TFA/g-dry weight) fromexponential phase to stationary phase, the hightest accumulation of total fatty acid was atthe stationary phase. At each temperature, the amount of fatty acids produced wasdifferent at a rapid growth temperature (25 C and 30 C ) more total fatty acid washigher utilized than the lower temperature (10 C, 15 C ). The proportion of GLA intotal fatty acid was much higher than any other fatty acids. The maximun content ofGLA was 45.6 % (%, g-GLA/g-TFA) at 10 C in an early log phase. The proportion ofGLA decreased along the growth phase. In contrast, the fatty acid Cl&l incresed andbecame the major composition at stationary phase (%, g-Cl&l/g-TFA). This may be as astorage fatty acid and it was an important precursor for the desaturation in M. rouxii24905. It should be noted that proportion of these two fatty acids always foundinversely at the same period of growth. The Degree of unsaturation which is describedthe desaturation process in fatty acid synthesis was much higher at low temperature thanhigh temperature. These were 1.86, 1.82, 1.61 and 1.39 &mole at 10 C, 15 C, 25 Cand 30 C, respectively.The effect of zinc ion on cell growth and fatty acid composition werestudied. ZnSO,@7H,O at concentration of 0.1, 1, 5, 10 and 50 rn@ were added into themedium. In the medium containing very high zinc concentration and without zinc, cellscould still grow but lower dry weight were obtained. There was no difference in dryweight obtained from the culture containing ZnSO, at 0.1, 1, 5 and 10 mg/l. Theproductions of cell mass were 6.03, 7.57, 7.41, 7.90, 7.87 and 6.43 g/l at 0, 0.1, 1, 5, 10and 50 mgjl, respectively. The concentration of zinc 0.1 mg/l was not affected to fattyacid composition, but the total fatty acid in was increased. At the concentration of zinc5 mgjl and 10 mg/l, the GLA content in cell was higher than any other concentrations.