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<p>A halophilic bacterium, named <i>Halomonas</i> sp. NEC-1 was isolated from the Nyer Co Salt Lake on the Xizang Plateau, SW China. The strain exhibited a broad pH tolerance range of 5–11, distinguishing it from <i>Halomonas alkaliphila</i> despite a 99% genetic similarity. Optimal growth conditions, determined through orthogonal experiments, were found to be 37 °C, 100-g/L salinity, and an initial pH of 6, resulting in a maximum OD<sub>600</sub> of 7.98±0.06. <i>Halomonas</i> sp. NEC-1 produced 545.43±25.10 mg/L of ectoine under optimal conditions of 75-g/L salinity, 40-g/L sodium glutamate, and an initial pH of 6. This production increased to 1 388.81±3.69 mg/L after five rounds of hypo-osmotic shocks. During the shocks, ectoine productivity remained stable at approximately 16.29±0.04 to 17.28±0.48 mg/(L·h), representing a 43.40%–52.11% increase compared to the rate without any shock (11.36±1.05 mg/(L·h)). Additionally, the expression of the <i>ectABC</i> gene cluster, related to ectoine synthesis, significantly increased following the shocks, enhancing ectoine production. The ectoine extract demonstrated notable protective effects on <i>Escherichia coli</i> and plasmid DNA. After 10 min of exposure at 60 °C, the colony count of <i>E. coli</i> treated with ectoine extract increased by 342% compared to treatment with distilled water. Furthermore, the ectoine extract protected plasmid DNA from 2,2′-Azobis (2-methylpropionamidine) dihydrochloride-induced damage. This study highlights <i>Halomonas</i> sp. NEC-1 is a promising strain for ectoine production and underscores the potential of microbial resources in salt lakes from Xizang region.</p>

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Halomonas sp. NEC-1, an ectoine-rich and wide pH tolerant halophilic bacterium isolated from a salt lake of Xizang, China

  • 期刊论文

  • 发表日期：

    2025年3月24日

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  • Yingchao Ma,
  • Zhongshi Sun,
  • Tashilhamo,
  • Yukang Li,
  • Hanying Zou,
  • Yuanliang Zhao,
  • Feiyang Lin,
  • Xuekai Han,
  • Liying Sui,
  • Chi Zhang

摘要

A halophilic bacterium, named Halomonas sp. NEC-1 was isolated from the Nyer Co Salt Lake on the Xizang Plateau, SW China. The strain exhibited a broad pH tolerance range of 5–11, distinguishing it from Halomonas alkaliphila despite a 99% genetic similarity. Optimal growth conditions, determined through orthogonal experiments, were found to be 37 °C, 100-g/L salinity, and an initial pH of 6, resulting in a maximum OD600 of 7.98±0.06. Halomonas sp. NEC-1 produced 545.43±25.10 mg/L of ectoine under optimal conditions of 75-g/L salinity, 40-g/L sodium glutamate, and an initial pH of 6. This production increased to 1 388.81±3.69 mg/L after five rounds of hypo-osmotic shocks. During the shocks, ectoine productivity remained stable at approximately 16.29±0.04 to 17.28±0.48 mg/(L·h), representing a 43.40%–52.11% increase compared to the rate without any shock (11.36±1.05 mg/(L·h)). Additionally, the expression of the ectABC gene cluster, related to ectoine synthesis, significantly increased following the shocks, enhancing ectoine production. The ectoine extract demonstrated notable protective effects on Escherichia coli and plasmid DNA. After 10 min of exposure at 60 °C, the colony count of E. coli treated with ectoine extract increased by 342% compared to treatment with distilled water. Furthermore, the ectoine extract protected plasmid DNA from 2,2′-Azobis (2-methylpropionamidine) dihydrochloride-induced damage. This study highlights Halomonas sp. NEC-1 is a promising strain for ectoine production and underscores the potential of microbial resources in salt lakes from Xizang region.