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
Photoprotection effect of the hyaluronic acid and ectoine composition was studied by evaluated its effects on inhibiting oxidative stress and MMP-1 production,ROS scavenging ability and promoting collagen synthesis in...Photoprotection effect of the hyaluronic acid and ectoine composition was studied by evaluated its effects on inhibiting oxidative stress and MMP-1 production,ROS scavenging ability and promoting collagen synthesis in skin cells under blue light irradiation.The result show that the composition is non-toxic to keratinocytes within a concentration of 5%.And the sample can significantly inhibit the increase of reactive oxygen species(ROS)caused by blue light irradiation at a concentration of 2%,and can also repaire the damaged skin by scavenge oxygen free radicals.At the same time,the composition can inhibit the increase of MMP-1 caused by blue light irradiation,so as to have the effect of inhibiting the decomposition of collagen and promoting the secretion of Collagen I.展开更多
Halomonas elongata,a moderately halophilicγ-proteobacterium of industrial interest,serves as a microbial cell factory for ectoine-a high-value compatible solute extensively utilized in biopharmaceuticals and cosmetic...Halomonas elongata,a moderately halophilicγ-proteobacterium of industrial interest,serves as a microbial cell factory for ectoine-a high-value compatible solute extensively utilized in biopharmaceuticals and cosmetics.While its ectoine biosynthesis potential is well-documented,the systemic metabolic adaptations underlying osmoadaptation remain poorly characterized,limiting rational engineering strategies for optimized production.To address this gap,we employed chemostat cultivation coupled with multi-omics integration(physiological profiling,metabolomics,and metabolic flux analysis)to dissect salt-dependent metabolic network rewiring in the model strain DSM 2581T under moderate(6.0%NaCl)and high salinity(13.0%NaCl).Results demonstrated that,under moderate salt conditions,a specific growth rate(μ)of 0.20 h1 significantly enhanced the ectoine-specific production rate(qp),intracellular ectoine content(pectoine),and yield coefficient(Yp/s),concurrent with redirection of carbon flux toward the Entner-Doudoroff(ED)pathway and ectoine biosynthesis.Under high salt conditions,flux through both the ED pathway and ectoine biosynthesis was further upregulated,whereas fluxes through the pentose phosphate(PP)pathway,tricarboxylic acid(TCA)cycle,and CO_(2) generation were downregulated.Simultaneously,suppression of the flux from malate to pyruvate enhanced oxaloacetate syn-thesis,thereby increasing the supply of key precursors including glutamate,aspartate,and NADPH to fuel ectoine biosynthesis.Stepwise salt reduction experiments revealed bidirectional metabolic flexibility:elevated salinity prioritized carbon investment into ED-driven ectoine production,whereas hypo-osmotic conditions reactivate respiratory activity and the TCA cycle to fuel energy metabolism.These findings establish H.elongata as a paradigm of dynamic flux rewiring,where carbon economy is strategically reallocated between stress-protective solute biosynthesis and energy homeostasis.This study bridges the knowledge gap in understanding the physi-ological characteristics of H.elongata and provides a foundation for improving ectoine production and engi-neering strains through metabolic optimization.展开更多
Ectoine is a natural macromolecule protector and synthesized by some extremophiles.It provides protections against radiation-mediated oxidative damages and is widely used as a bioactive ingredient in pharmaceutics and...Ectoine is a natural macromolecule protector and synthesized by some extremophiles.It provides protections against radiation-mediated oxidative damages and is widely used as a bioactive ingredient in pharmaceutics and cosmetics.To meet its growing commercial demands,we engineered Escherichia coli strains for the high-yield production of ectoine.The ectABC gene cluster from the native ectoine producer Halomonas elongata was intro-duced into different Escherichia coli(E.Coil)strains via plasmids and 0.8 g L^(-1)of ectoine was produced in flask cultures by engineered E.coli BL21(DE3).Subsequently,we designed the ribosome-binding sites of the gene cluster to fine-tune the expressions of genes ectA,ectB,and ectC,which increased the ectoine yield to 1.6 g L^(-1).After further combinatorial overexpression of Corynebacterium glutamicum aspartate kinase mutant(G1A,C932T)and the H.elongate aspartate-semialdehyde dehydrogenase to increase the supply of the precursor,the titer of ectoine reached to 5.5 g L^(-1)in flask cultures.Finally,the engineered strain produced 60.7 g L^(-1)ectoine in fed-batch cultures with a conversion rate of 0.25 g/g glucose.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.
文摘Photoprotection effect of the hyaluronic acid and ectoine composition was studied by evaluated its effects on inhibiting oxidative stress and MMP-1 production,ROS scavenging ability and promoting collagen synthesis in skin cells under blue light irradiation.The result show that the composition is non-toxic to keratinocytes within a concentration of 5%.And the sample can significantly inhibit the increase of reactive oxygen species(ROS)caused by blue light irradiation at a concentration of 2%,and can also repaire the damaged skin by scavenge oxygen free radicals.At the same time,the composition can inhibit the increase of MMP-1 caused by blue light irradiation,so as to have the effect of inhibiting the decomposition of collagen and promoting the secretion of Collagen I.
基金supported by the financial support of research projects from the National Key R&D Program of China(No.2020YFA0906800)National Natural Science Foundation of China(No.32071471).
文摘Halomonas elongata,a moderately halophilicγ-proteobacterium of industrial interest,serves as a microbial cell factory for ectoine-a high-value compatible solute extensively utilized in biopharmaceuticals and cosmetics.While its ectoine biosynthesis potential is well-documented,the systemic metabolic adaptations underlying osmoadaptation remain poorly characterized,limiting rational engineering strategies for optimized production.To address this gap,we employed chemostat cultivation coupled with multi-omics integration(physiological profiling,metabolomics,and metabolic flux analysis)to dissect salt-dependent metabolic network rewiring in the model strain DSM 2581T under moderate(6.0%NaCl)and high salinity(13.0%NaCl).Results demonstrated that,under moderate salt conditions,a specific growth rate(μ)of 0.20 h1 significantly enhanced the ectoine-specific production rate(qp),intracellular ectoine content(pectoine),and yield coefficient(Yp/s),concurrent with redirection of carbon flux toward the Entner-Doudoroff(ED)pathway and ectoine biosynthesis.Under high salt conditions,flux through both the ED pathway and ectoine biosynthesis was further upregulated,whereas fluxes through the pentose phosphate(PP)pathway,tricarboxylic acid(TCA)cycle,and CO_(2) generation were downregulated.Simultaneously,suppression of the flux from malate to pyruvate enhanced oxaloacetate syn-thesis,thereby increasing the supply of key precursors including glutamate,aspartate,and NADPH to fuel ectoine biosynthesis.Stepwise salt reduction experiments revealed bidirectional metabolic flexibility:elevated salinity prioritized carbon investment into ED-driven ectoine production,whereas hypo-osmotic conditions reactivate respiratory activity and the TCA cycle to fuel energy metabolism.These findings establish H.elongata as a paradigm of dynamic flux rewiring,where carbon economy is strategically reallocated between stress-protective solute biosynthesis and energy homeostasis.This study bridges the knowledge gap in understanding the physi-ological characteristics of H.elongata and provides a foundation for improving ectoine production and engi-neering strains through metabolic optimization.
基金supported by the National Key Research and Development Program of China(2021YFC2100800)the Jiangsu Province Natural Science Fund for Distinguished Young Scholars(BK20200025)+2 种基金the National Natural Science Foundation of China(32000058)a grant from the Key Technologies R&D Program of Jiangsu Province(BE2019630)the National First-class Discipline Program of Light Industry Technology and Engineering(LITE2018-16).
文摘Ectoine is a natural macromolecule protector and synthesized by some extremophiles.It provides protections against radiation-mediated oxidative damages and is widely used as a bioactive ingredient in pharmaceutics and cosmetics.To meet its growing commercial demands,we engineered Escherichia coli strains for the high-yield production of ectoine.The ectABC gene cluster from the native ectoine producer Halomonas elongata was intro-duced into different Escherichia coli(E.Coil)strains via plasmids and 0.8 g L^(-1)of ectoine was produced in flask cultures by engineered E.coli BL21(DE3).Subsequently,we designed the ribosome-binding sites of the gene cluster to fine-tune the expressions of genes ectA,ectB,and ectC,which increased the ectoine yield to 1.6 g L^(-1).After further combinatorial overexpression of Corynebacterium glutamicum aspartate kinase mutant(G1A,C932T)and the H.elongate aspartate-semialdehyde dehydrogenase to increase the supply of the precursor,the titer of ectoine reached to 5.5 g L^(-1)in flask cultures.Finally,the engineered strain produced 60.7 g L^(-1)ectoine in fed-batch cultures with a conversion rate of 0.25 g/g glucose.
