Research on the Stability of the Recombinant Production of Omega-3 Fatty Acids in Industrial Strains Using the Gene Cluster Isolated from Shewanella baltica MAC1

In past decades, there has been increasing awareness of the effects of omega-3 (n-3) fatty acids, especially EPA and DHA on human health. Realizing that these fatty acids are deeply involved in regulating human diseases as well as helping the proper development of the immune and nervous systems as well as visual acuity, more people began consuming omega-3 fatty acids in the form of nutritional supplements. So far, fish and fish oil are the main dietary sources of EPA and DHA. However, fish stocks have been depleted, therefore alternative sources of these fatty acids need to be explored. In this study, long-term stability of the plasmid carrying the 20 kb EPA/DHA biosynthesis gene cluster in the transformed E. coli EPI300T1 without antibiotic pressure as well as its recombinant production of EPA and DHA were studied. Moreover, molecular methods were used to transform Streptococcus thermophilus ST21 with plasmid pEDSB (modified plasmid vector pIL252 carrying the 20 kb insert), followed by a series of GC and GC/MS analyses to test recombinant production of EPA and DHA by S. thermophilus ST21. Our results showed recombinant production of EPA by S. thermophilus. However, production of EPA synthesized by transformed S. thermophilus was lower than that by recombinant E. coli. In addition, recombinant E. coli was able to stably maintain the 20 kb EPA/DHA gene cluster as compared to S. thermophilus. Our data confirmed transformation of the EPA/DHA gene cluster to gram-negative and gram-positive bacteria as well as its stability in E. coli.