Effect of fermentation conditions on lipase production by Candida utilis

A wild yeast strain isolated from spoiled soybean oil and identified as Candida utilis initially presented rather low lipase activity (approximately 4 IU dm(-3)) in submerged culture in a universal yeast medium containing 2 % malt extract. Studies were undertaken to improve the lipase production. The best yields of lipase were obtained with a medium Supplemented with caprylic and oleic acids as inducers, but higher concentrations of the former (> 0.5 %) had a negative effect on the lipase production and cell growth. The type of nitrogen Source seemed also to be very important. The highest lipolytic activity of 284 IU dm(-3) was achieved after 5 days of fermentation in a medium containing oleic acid and hydrolyzed casein as carbon and nitrogen sources, respectively, and supplemented with Tween 80 (R). It was shown that optimization of the fermentation conditions can lead to a significant improvement in the lipase production (more than 70-fold higher compared to the initial value obtained in the non-optimized medium).