Efficient fermentative production of SAM through multidimensional engineering of Saccharomyces cerevisiae.

Abstract

S-Adenosyl-L-methionine (SAM), an important biochemical substance, is experiencing increased demand due to its versatile applications in the medical field. Although Saccharomyces cerevisiae has been adapted as a promising platform for SAM production, the issue of SAM productivity is still very interesting. In this study, a systematic approach that consists of genome shuffling, genetic engineering, and fermentation process optimization strategies was established. Firstly, haploids of mutant T11-1 and P15-33 were prepared and treated with ultraviolet irradiation (UV) and atmospheric and room temperature plasma (ARTP) compound mutagenesis, which aids to increase SAM production to 1.25, 1.34 g/L, respectively. Genome shuffling was performed with cycloheximide-resistant protoplast of mutant T5-8-1 and hygromycin B-resistant protoplasts of mutant P4-2-4. The resulting fusant TRP60, with a SAM titer of 1.36 g/L, was subjected to transcriptome analysis. Subsequently, hemoglobin from vitreoscilla has been introduced into fusant TRP60 to increase ATP supply and then strengthening the synthesis pathway of SAM, which significantly elevated SAM titer to 2.06 g/L. Finally, the SAM titer of fusant TRP60-vgb-SAM2 reached 14.22 g/L in a 5 L bioreactor with an optimized fed-batch fermentation. Therefore, fusant TRP60-vgb-SAM2 may serve as a candidate for industrial production of SAM.