Abstract
Egicoccus halophilus EGI 80432T, 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 80432T 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 80432T 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 80432T’s application in ecological restoration.
Key Points
• Salt stress affected gene expressions responsible for carbohydrate and energy metabolisms of E. halophilus EGI 8042T.
• E. halophilus EGI 80432T significantly accumulated compatible solutes under salt stress.
• E. halophilus EGI 80432T adopted a “compatible solute” strategy to withstand high salt stress.
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Data availability
The RNA-seq data reported in the current study are available in the NCBI SRA database (Bioproject: PRJNA665624 and the accession numbers: SRR12710815-SRR12710823).
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Acknowledgments
This research was supported by the National Natural Science Foundation of China (Nos: 32061143043, 32050410306, 32000084, and 91751206), Xinjiang Uygur Autonomous Region regional coordinated innovation project (Shanghai cooperation organization science and technology partnership program) (No. 2020E01047), and China Postdoctoral Science Foundation (No. 2019M662952).
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DDC, WSS, and WJL conceived and designed the research. DDC conducted experiments, analyzed the data, and wrote the manuscript. BZF provided advice during the initial research stage and contributed analytical tools. AM, YHL, LL, and OAAM modified the first draft of this manuscript. All authors read and approved the manuscript.
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Chen, DD., Fang, BZ., Manzoor, A. et al. Revealing the salinity adaptation mechanism in halotolerant bacterium Egicoccus halophilus EGI 80432T by physiological analysis and comparative transcriptomics. Appl Microbiol Biotechnol 105, 2497–2511 (2021). https://doi.org/10.1007/s00253-021-11190-5
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DOI: https://doi.org/10.1007/s00253-021-11190-5