The mechanism of improved intracellular organic selenium and glutathione contents in selenium-enriched Candida utilis by acid stress

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• 作者：Gao-Chuan Zhang ; Da-Hui Wang ; Dong-Hua Wang…
• 关键词：Selenium ; enriched yeast ; Candida utilis ; Glutathione ; Acid stress ; ATP ; RNA ; Seq
• 刊名：Applied Microbiology and Biotechnology
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：101
• 期：5
• 页码：2131-2141
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Microbiology; Microbial Genetics and Genomics; Biotechnology;
• 出版者：Springer Berlin Heidelberg
• ISSN：1432-0614
• 卷排序：101

文摘

Batch culture of Candida utilis CCTCC M 209298 for the preparation of selenium (Se)-enriched yeast was carried out under different pH conditions, and maximal intracellular organic Se and glutathione (GSH) contents were obtained in a moderate acid stress environment (pH 3.5). In order to elucidate the physiological mechanism of improved performance of Se-enriched yeast by acid stress, assays of the key enzymes involved in GSH biosynthesis and determinations of energy supply and regeneration were performed. The results indicated that moderate acid stress increased the activity of γ-glutamylcysteine synthetase and the ratios of NADH/NAD+ and ATP/ADP, although no significant changes in intracellular pH were observed. In addition, the molecular mechanism of moderate acid stress favoring the improvement of Se-yeast performance was revealed by comparing whole transcriptomes of yeast cells cultured at pH 3.5 and 5.5. Comparative analysis of RNA-Seq data indicated that 882 genes were significantly up-regulated by moderate acid stress. Functional annotation of the up-regulated genes based on gene ontology and the Kyoto Encyclopedia of Genes and Genome (KEGG) pathway showed that these genes are involved in ATP synthesis and sulfur metabolism, including the biosynthesis of methionine, cysteine, and GSH in yeast cells. Increased intracellular ATP supply and more amounts of sulfur-containing substances in turn contributed to Na₂SeO₃ assimilation and biotransformation, which ultimately improved the performance of the Se-enriched C. utilis.