Department of Food Hygiene and Control, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef, 62511, Egypt.
Bioproducts Research Chair, Zoology Department, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia.
Sci Rep. 2020 Sep 15;10(1):15076. doi: 10.1038/s41598-020-72054-y.
It is well known that the quality and quantity of bioactive metabolites in plants and microorganisms are affected by environmental factors. We applied heat stress as a promising approach to stimulate the production of antioxidants in four heat-tolerant bacterial strains (HT1 to HT4) isolated from Aushazia Lake, Qassim Region, Saudi Arabia. The phylogenetic analysis of the 16S rRNA sequences indicated that HT1, HT3 and HT4 belong to genus Bacillus. While HT2 is closely related to Pseudooceanicola marinus with 96.78% similarity. Heat stress differentially induced oxidative damage i.e., high lipid peroxidation, lipoxygenase and xanthine oxidase levels in HT strains. Subsequently, heat stress induced the levels of flavonoids and polyphenols in all strains and glutathione (GSH) in HT2. Heat stress also improved the antioxidant enzyme activities, namely, CAT, SOD and POX in all strains and thioredoxin activity in HT3 and HT4. While GSH cycle (GSH level and GPX, GR, Grx and GST activities) was only detectable and enhanced by heat stress in HT2. The hierarchical cluster analysis of the antioxidants also supported the strain-specific responses. In conclusion, heat stress is a promising approach to enhance antioxidant production in bacteria with potential applications in food quality improvement and health promotion.
众所周知，植物和微生物中生物活性代谢物的质量和数量受到环境因素的影响。我们应用热应激作为一种有前途的方法来刺激从沙特阿拉伯盖西姆地区奥沙齐亚湖分离出的四种耐热细菌（HT1 到 HT4）产生抗氧化剂。16S rRNA 序列的系统发育分析表明，HT1、HT3 和 HT4 属于芽孢杆菌属。而 HT2 与 Pseudooceanicola marinus 的相似度高达 96.78%。热应激在 HT 菌株中差异诱导氧化损伤，即高脂质过氧化、脂氧合酶和黄嘌呤氧化酶水平。随后，热应激诱导所有菌株中的类黄酮和多酚以及 HT2 中的谷胱甘肽 (GSH) 水平升高。热应激还提高了所有菌株中的抗氧化酶活性，即 CAT、SOD 和 POX，以及 HT3 和 HT4 中的硫氧还蛋白活性。而 GSH 循环（GSH 水平和 GPX、GR、Grx 和 GST 活性）仅在 HT2 中可检测到并受热应激增强。抗氧化剂的层次聚类分析也支持菌株特异性反应。总之，热应激是一种有前途的方法，可以提高细菌中抗氧化剂的产生，具有改善食品质量和促进健康的潜在应用。
