Fatty Acid Profiling of Lyophilized Yeast Cells

Lyophilized yeast cells were disrupted by freeze-thawing in hydrochloric acid and extracted for fatty acids using the chloroform-methanol method, dried by nitrogen blowing, and then methylated by adding 2 mL of 1% (v/v) sulfuric acid-methanol for 60 min in 80 °C [16 (link)]. Fatty acid profiles were analyzed as fatty acid methyl esters (FAMEs) by gas chromatography-mass spectrometry (GC-MS; GCMS-QP2010 Ultra, Shimadzu, Kyoto, Japan). Pentadecanoic acid (C15:0) served as an internal standard, and relative quantification was based on the ratio of each fatty acid to the internal standard peak area. The temperature program was as previously detailed [17 (link)]. The transformation efficiency of the mutants was calculated using the substrate conversion rate: Rate of substrate conversion (%) = 100 × [(product)/(product + substrate)], from three independent experiments.