Chen Dai-Di, Fang Bao-Zhu, Manzoor Ahmad, Liu Yong-Hong, Li Li, Mohamad Osama Abdalla Abdelshafy, Shu Wen-Sheng, Li Wen-Jun
Institute of Ecological Science, School of Life Science, South China Normal University, Guangzhou, 510631, People's Republic of China.
State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, People's Republic of China.
Appl Microbiol Biotechnol. 2021 Mar;105(6):2497-2511. doi: 10.1007/s00253-021-11190-5. Epub 2021 Feb 24.
Egicoccus halophilus EGI 80432, a halotolerant bacterium isolated from a saline-alkaline soil, belongs to a member of the class Nitriliruptoria, which exhibits high adaptability to salt environments. At present, the detailed knowledge of the salinity adaptation strategies of Nitriliruptoria was limited except for one research by using comparative genomics analysis. Here, we investigated the salinity adaptation mechanism of E. halophilus EGI 80432 by comparative physiological and transcriptomic analyses. The results of physiological analyses showed that trehalose and glutamate were accumulated by salt stress and showed the maximum at moderate salinity condition. Furthermore, the contents of histidine, threonine, proline, and ectoine were increased with increasing salt concentration. We found that both 0% and 9% NaCl conditions resulted in increased expressions of genes involved in carbohydrate and energy metabolisms, but negatively affected the Na efflux, iron, and molybdate transport. Moreover, the high salt condition led to enhancement of transcription of genes required for the synthesis of compatible solutes, e.g., glutamate, histidine, threonine, proline, and ectoine, which agree with the results of physiological analyses. The above results revealed that E. halophilus EGI 80432 increased inorganic ions uptake and accumulated trehalose and glutamate in response to moderate salinity condition, while the salinity adaptation strategy was changed from a "salt-in-cytoplasm" strategy to a "compatible solute" strategy under high salinity condition. The findings in this study would promote further studies in salt tolerance molecular mechanism of Nitriliruptoria and provide a theoretical support for E. halophilus EGI 80432's application in ecological restoration.Key Points• Salt stress affected gene expressions responsible for carbohydrate and energy metabolisms of E. halophilus EGI 8042.• E. halophilus EGI 80432 significantly accumulated compatible solutes under salt stress.• E. halophilus EGI 80432 adopted a "compatible solute" strategy to withstand high salt stress.
嗜盐埃吉球菌EGI 80432是从盐碱土壤中分离出的一种耐盐细菌，属于腈裂解菌纲的成员，对盐环境具有高度适应性。目前，除了一项利用比较基因组学分析的研究外，关于腈裂解菌纲盐适应性策略的详细知识还很有限。在此，我们通过比较生理学和转录组学分析，研究了嗜盐埃吉球菌EGI 80432的盐适应机制。生理学分析结果表明，海藻糖和谷氨酸在盐胁迫下积累，并在中等盐度条件下达到最大值。此外，组氨酸、苏氨酸、脯氨酸和四氢嘧啶的含量随着盐浓度的增加而增加。我们发现，0%和9% NaCl条件均导致参与碳水化合物和能量代谢的基因表达增加，但对Na外流、铁和钼酸盐转运产生负面影响。此外，高盐条件导致参与合成相容性溶质（如谷氨酸、组氨酸、苏氨酸、脯氨酸和四氢嘧啶）所需基因的转录增强，这与生理学分析结果一致。上述结果表明，嗜盐埃吉球菌EGI 80432在中等盐度条件下增加了无机离子的吸收，并积累了海藻糖和谷氨酸，而在高盐条件下，其盐适应策略从“盐入细胞质”策略转变为“相容性溶质”策略。本研究结果将促进对腈裂解菌纲耐盐分子机制的进一步研究，并为嗜盐埃吉球菌EGI 80432在生态修复中的应用提供理论支持。要点：• 盐胁迫影响嗜盐埃吉球菌EGI 8042碳水化合物和能量代谢相关基因的表达。• 嗜盐埃吉球菌EGI 80432在盐胁迫下显著积累相容性溶质。• 嗜盐埃吉球菌EGI 80432采用“相容性溶质”策略来抵御高盐胁迫。
