The unsaturated fatty acids of the alga chlorella

Abstract

HE purpose of this paper is to elucidate further the composition of the unsaturated fatty acids of the fresh water alga Chlorella pyrenoidosa grown in pure culture in pilot plant quantities. In 1948 Milner (1) had shown the effect of certain environmental conditions on the yield of Chlorella and its lipid content. An excellent discussion of these results and the economic aspects of the problem appeared in 1951 (2) in this journal. Significant to us was the observation that the cell yield increased with increased nitrogen content of nutrient media but that the cells thus obtained had a low content of fatty acid. These however were highly unsaturated as indicated by iodine numbers of over 160. Restriction of nitrogen in the media gave poor yield of C hlorella, but the fatty acid content of the cells increased tenfold to over 60%. Iodine number of the fatty acids dropped to 125. The one sample which we examined was the low-lipid, high-iodine number type. The sample was obtained from Arthur D. Little Inc. Pilot plant studies at the laboratory were apparently aimed at high cell and high protein yields. Milner found that the fatty acids were almost all of C~s and C~s chain length, tte noted that the iodine number of the C~6 fraction indicated at least 17% of triene fatty acids. Polyunsaturated C~6 fatty acids are relatively rare. Heyes and Sborland (3) have re