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 alkaliphi...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℃,100-g/L salinity,and an initial pH of 6,resulting in a maximum OD_(600) 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 1388.81±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℃,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.展开更多
基金Supported by the Key Science and Technology Program of Xizang Autonomous Region(No.XZ202301ZY0012N)the Key Fisheries Resources and Environmental Survey Project in the Southwest Region(No.CJW2023034)the National Natural Science Foundation of China(No.42306106)。
文摘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℃,100-g/L salinity,and an initial pH of 6,resulting in a maximum OD_(600) 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 1388.81±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℃,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.
