酸胁迫在提升富硒/GSH产朊假丝酵母性能中的作用

The Role of Acid Stress on Improved Performance of Selenium/glutathione-Enriched Candida utilis

为了提高富硒产朊假丝酵母胞内有机硒和谷胱甘肽(GSH)的含量,考察了不同pH环境对富硒过程中的酵母细胞生长、GSH合成以及有机硒转化的影响。结果发现弱酸胁迫有利于富硒/GSH产朊假丝酵母性能的提升,其中pH 3.5时最大胞内有机硒和GSH含量分别为1.13 mg/g和12.3 mg/g。通过对酵母胞外蛋氨酸浓度、胞内pH值以及NADH/NAD+、ATP/ADP比率进行分析,部分解释了弱酸胁迫提升富硒/GSH产朊假丝酵母性能的原因。为进一步提高产朊假丝酵母的营养功能提供了可行的思路。

Intracellular organic selenium and glutathione contents are the two most important characteristics of high performance of selenium-enriched yeast. In order to improve the performance of selenium/glutathione- enriched Candida utilis, the effects of diverse pH conditions on cell growth, glutathione biosynthesis and the biotransformation of inorganic selenium to organic selenium during selenium enrichment were investigated. It was indicated that the moderate acid stress was favor of the increased intracellular contents of organic selenium and glutathione, as well as the decreased level of the oxidized compound as malondialdehyde. The maximum levels of the intracellular organic selenium and glutathione were obtained at pH 3.5 as 1. 13 mg/g and 12.3 rag/g, respectively. Based on the analysis of residual methionine in the medium, intracellular pH, the ratios of NADH/ NAD ~ and ATP/ADP, the reason of the improved performance of selenium/glutathione-enriched Candida utilis by moderate acid stress were partly interpreted. The results presented will give a feasible approach for further enhanced nutrimental function of Candida utilis.