Secretory production of ricinoleic acid in fission yeast Schizosaccharomyces pombe

We have succeeded to produce a high content of ricinoleic acid (RA), a hydroxylated fatty acid with great values as a petrochemical replacement, in fission yeast Schizosaccharomyces pombe by introducing Claviceps purpurea oleate Delta 12-hydroxylase gene (CpFAH12). Although the production was toxic to S. pombe cells, we solved the problem by identifying plg7, encoding phospholipase A2, as a multicopy suppressor. Characterization of the RA-tolerant strains suggested that the removal of RA moieties from phospholipids would be the suppression mechanism by plg7. In this study, we extended our analysis and report our new discovery that the overexpression of plg7 enabled cells to secrete free RA into culture media. When the FAH12 integrant in the absence of the overexpressed plg7 was grown at 20 A degrees C for 11 days, the amount of intracellular RA reached 200.1 mu g/ml of culture and only 69.3 mu g/ml of RA was detected in culture media. On the other hand, the FAH12 integrant harboring the plg7 multicopy plasmid secreted RA in the media (184.5 mu g/ml) without decreasing the amount in the cells, i.e., a significantly higher total secretion and a lead to making RA by its secretory production in S. pombe.