Isolation of a yeast growing on sardine oil and its characteristics

Abstract

A yeast strain, FO-144Cl, was isolated from a soil sample, using crude sardine oil, which contains a large quantity of poly-unsaturated long-chain fatty acids, as a sole carbon source. This strain was identified as a species of Candida. A medium for its growth was optimized by statistical methods and optimal temperature for the growth was from 28 to 30°C. Among the natural oils and fats tested, the yeast grew best on olive oil and grew better on the crude sardine oil than on a refined one. The yield of dry cells was 17.6 mg/ml after 24 h, using 2% crude sardine oil. The maximum growth rate was 0.36, 0.25, and 0.21 h⁻¹ with crude sardine oil, soybean oil, and olive oil, respectively. The content of crude fat in the yeast cells was 15.1% and half of the total cell lipid was triglyceride. Fatty acid compositions of the lipid and oily fractions left in the medium after cultivation were analyzed. Little unsaturated long-chain fatty acids (>C₁₈) was observed in the cell lipids, but they were left concentrated in the medium.