Growth, Fatty Acid Composition and Extracellular Enzyme Production in the Thraustochytrid, Aurantiochytrium Cultured in Molasses-Based Medium

Abstract

The production of oil by thraustochytrids is still costly because of its necessary and expensive culture medium. We evaluated the growth, lipid production, and fatty acid composition in an inexpensive, molasses-based (M) medium. Newly isolated thraustochytrid strains were identified as members of genus Aurantiochytrium based on 18S rRNA gene sequences. Isolated strains were repeatedly cultured in M medium for acclimatization to the medium. Acclimatized and non-acclimatized strains were cultured in basal GY medium and M medium. The lipid in the cultured cells were extracted by the Folch method, and the fatty acid composition was analyzed by gas chromatograph. The growth and lipid production in the non-acclimatized strains were significantly inhibited by culturing in M medium, whereas the growth and lipid production were improved by acclimatization treatment in the same medium. The fatty acid composition in the cultured cells were affected by the M medium compared to the basal GY medium. The production of some enzymes such as leucine and valine aryl-amidase was suppressed in the M medium, and the activities recovered by acclimatization treatment. The growth of some strains in the molasses medium was thus recovered by the acclimatization process, and the profiles of extracellular enzymes were also affected.