Effect of cultural conditions on the fatty acid composition of Thiobacillus novellus.

The fatty acid content of Thiobacillus novellus was determined under various cultural conditions. Four fatty acids, C(16:0), C(18:0), C(18:1), and a C(19) cyclopropane acid (C(19:cyc)), generally accounted for 90 to 99% of the total acids. Phosphate concentration, temperature, culture agitation, and the presence of branch-chain precursors had no significant effect on cellular fatty acids. Autotrophically grown cells contained more saturated C(16) and C(18) acids than did heterotrophic ones, and the sum of the percentages of the C(18:1) and the C(19:cyc) acids was consistently higher in the heterotrophs. When the inorganic medium was supplemented with biotin, autotrophic cells produced more C(19:cyc) and much less C(18:1) than did autotrophs in unsupplemented medium. Heterotrophic cells grown with biotin also showed a marked reduction of the unsaturated acid and an increase in the cyclopropane acid, except when glutamatecitrate medium was employed, in which case the opposite effect was noted. Two different biotin-supplemented media yielded cells with 75 to 77% of the total fatty acids being the C(19) cyclopropane acid, one of the highest reported values for this class of acid.