Nho Soo Bin,Do Sang-Hun,Oh Seongjin,Park Yong-Cheol,Kim Sun-Ki
This study aimed to develop a non-genetically modified organism (non-GMO) Saccharomyces cerevisiae strain with enhanced glutathione production using UV-induced random mutagenesis. Among 30 wild-type strains, S. cerevisiae KACC 48331 was selected for its high glutathione production. A #14 mutant with significantly higher glutathione content was isolated via acrolein resistance screening. Optimal batch fermentation was established at 20 °C and pH 4.5 using a cost-effective medium of molasses and corn steep liquor (CSL). In fed-batch fermentation, the #14 mutant achieved 1.98 g/L of glutathione using molasses and CSL as carbon and nitrogen sources, comparable to yields from expensive complex media containing peptone and yeast extract. Notably, over 99% of the glutathione produced was in the reduced, biologically active form. These results demonstrate the feasibility of using non-GMO yeast and industrial by-products for sustainable and economical glutathione production.
Yujia Zhou,Zhiming Li,Xinghui Xie,Xingtao Zhou,Jielun Hu,Shaoping Nie
Gellan is a microbial polysaccharide synthesized by Sphingomonas paucimobilis , and is widely utilized in the food and pharmaceutical industries, as well as in other fields. However, much remains unknown about the key genes involved in the gellan synthesis pathway. In this study, ultraviolet (UV) and atmospheric room temperature plasma (ARTP) were employed to induce mutations in S . paucimobilis ATCC31461 (Sp31461 NC), and ultimately resulting a high-yield mutant strain (Sp31461 UA) with a yield increase of 120 % from 3.6 g/L to 8.3 g/L. The growth curve, monosaccharide composition and molecular weight indicated that mutagenesis accelerated the growth of the strain, but did not affect gellan's basic physicochemical property. A combined analysis of transcriptomic and metabolomic demonstrated that the differentially expressed genes and metabolites resulting from mutations were primarily enriched in pathways related to energy metabolism, among which potential key genes such as pgi , clpB , ycaJ associated with gellan yield, were further verified by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and gene overexpression. Notably, the strain overexpression the pgi gene resulted in a 20 % increase in gellan yield compared to the Sp31461 UA strain, reaching 10.0 g/L. In summary, the energy metabolism pathway in S . paucimobilis is closely linked to gellan biosynthesis, and high-yield strains of gellan can be developed through mutagenesis breeding and the overexpression of key genes identified by transcriptomics and metabolomics. This research offers valuable scientific insights for the industrial production and application of gellan.
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