B-3 exopolysaccharide is extracted from the Antarctic psychrophilic bacterium Psychrobacter sp. B-3. We have previously shown that it activates macrophages and affects their immunoregulatory activities. To determine w...B-3 exopolysaccharide is extracted from the Antarctic psychrophilic bacterium Psychrobacter sp. B-3. We have previously shown that it activates macrophages and affects their immunoregulatory activities. To determine what genes are affected during this process, we detected the genes differentially expressed in cells of RAW264.7 macrophages treated with B-3 exopolysaccharide by transcriptomic analysis. B-3 exopolysaccharide treatment caused differential expression of 420 genes, of which 178 were up-regulated and 242 were down-regulated. These genes were shown to be involved in many aspects of cell function, mainly metabolism and immunity. Genes were enriched in multiple immune-related pathways, and the most significantly enriched genes were involved in antigen processing and presentation pathways. The pathway in which differentially expressed genes were the most significantly enriched was the metabolic pathway; specifically, the expression of many metabolic enzyme genes was altered by B-3 exopolysaccharide treatment. Additionally, the genes involved in metabolisms of amino acids, carbohydrates, lipids and nucleotides, varied to certain degrees. B-3 exopolysaccharide, therefore, appears to directly affect the immune function of RAW264.7 macrophages as an immunostimulant, or to indirectly change intracellular metabolism. This is the first study to determine the effect of an Antarctic psychrophilic bacterial exopolysaccharide on RAW264.7 macrophages. Our findings provide an important reference for research into the regulation of macrophage immune function by different polysaccharides.展开更多
Random mutagenesis is commonly used to study gene function. The screening of mutants exhibiting specific pheno- types assists in the identification of phenotype-related genes. In the current study, we isolated Antarct...Random mutagenesis is commonly used to study gene function. The screening of mutants exhibiting specific pheno- types assists in the identification of phenotype-related genes. In the current study, we isolated Antarctic bacteria, and developed a transposon Tn5 mutagenesis system. A total of 26 strains were isolated from seawater and freshwater near Antarctic King Sejong Research Station, King George Island. Six Psychrobacter strains were identified as psychrophilic, with optimal growth tempera- tures of 10~C or 15~C Psychrobacter cryohalolentis PAMC 21807 with a high growth rate at 4~C was selected for transposon mutagenesis. Tri-parental conjugation with a plasmid containing Tn5 produced 13 putative recombinants containing the selectable marker. Genomic Southern hybridization confirmed Tn5 existed as episomes for seven recombinants, and for a single recombinant, Tn5 was integrated into the genome of Psychrobacter cryohalolentis PAMC 21807. The result indicates that the mutagenesis method, although successful, has a relatively low rate. The psychrophilic bacteria isolated in this study may be a useful resource for studying cold adaptation mechanisms, and the mutagenesis method can be applied to genetic analysis.展开更多
The key functional genes involved in temperature adaption of the Antarctic psychrotrophic bacterium Psychrobacter sp. G. were identified by transcriptomic sequencing. We analyzed the global transcriptional profile of ...The key functional genes involved in temperature adaption of the Antarctic psychrotrophic bacterium Psychrobacter sp. G. were identified by transcriptomic sequencing. We analyzed the global transcriptional profile of Psychrobacter sp. G under cold stress（0°C） and heat stress（30°C）, with the optimal growth temperature 20°C as the control. There were large alterations of the transcriptome profile, including significant upregulation of 11 and 12 transcripts as well as significant downregulation of 47 and 42 transcripts in the cold and heat stress groups, respectively, compared to the control. The expression of various genes encoding enzymes and transcriptional regulators, including Pfp I and Tet R family transcriptional regulators under heat stress, as well as the expression of DEAD/DEAH box helicase and the Icl R family of transcriptional regulators under cold stress, were upregulated significantly. The expression of several genes, most affiliated with Ton Bdependent receptor and siderophore receptor, was downregulated significantly under both heat and cold stress. Many of the genes associated with the metabolism of fatty acid and ABC transporters were regulated differentially under different temperature stress. The results of this survey of transcriptome and temperature stress-relevant genes contribute to our understanding of the stress-resistant mechanism in Antarctic bacteria.展开更多
Abstract Heat shock proteins （Hsps）, produced by organisms under high temperature stimulation, play important roles in protein folding, translocation, and refolding/degradati0n. In this study, we investigated the ex...Abstract Heat shock proteins （Hsps）, produced by organisms under high temperature stimulation, play important roles in protein folding, translocation, and refolding/degradati0n. In this study, we investigated the expression level of the GrpE Hsp gene Hsp845 of Psychrobacter sp. G under different temperature and salinity stresses by quantitative real-time PCR and western blotting, respectively. At both transcriptional and translational levels, Hsp845 gene expression was induced by high temperature （30~C） and inhibited by low temperatures （0~C and 10~C）. Hsp845 expression was also induced both by the absence of salt （0%0） and high salinity （90%0 and 120%o） at the transcriptional level, but was only induced by high salinity （90%0 and 120%o） at the translational level. In a combined stress treatment, Hsp845 was more sensitive to high temperature than to salinity at both transcriptional and translational levels. The increase in the translational-level expression of Hsp845 lagged behind that at the transcriptional level, and Hsp845 maximum expression was also higher at the transcriptional than at the translational level. In the absence of salt, transcriptional- and translational-level expressions exhibited opposite patterns, suggesting that the underlying mechanism requires further study.展开更多
Psychrobacter species are gram-negative bacteria in the Moraxellaceae family.These bacteria are considered rare opportunistic human pathogens,and the infection sites include blood,cerebral spinal fluid,wounds,urine,th...Psychrobacter species are gram-negative bacteria in the Moraxellaceae family.These bacteria are considered rare opportunistic human pathogens,and the infection sites include blood,cerebral spinal fluid,wounds,urine,the ears,and the eyes.Few cases of human infection by these species have been described previously.We report a case of a 10-year-old boy with postneurosurgical bacteremia due to Psychrobacter sanguinis infection.This infection was difficult to identify using routine biochemical phenotypical tests.Sequencing of 16S rRNA was performed to identify this pathogen.The patient was successfully treated with antibiotics.In conclusion,P.sanguinis infections are rare but should be considered when cultures remain negative for common pathogens.展开更多
A psychrophilic aerobic denitrifying bacterium,strain S1-1,was isolated from a biological aerated filter conducted for treatment of recirculating water in a marine aquaculture system.Strain S1-1 was preliminarily iden...A psychrophilic aerobic denitrifying bacterium,strain S1-1,was isolated from a biological aerated filter conducted for treatment of recirculating water in a marine aquaculture system.Strain S1-1 was preliminarily identified as Psychrobacter sp.based on the analysis of its 16S rRNA gene sequence,which showed 100% sequence similarity to that of Psychrobacter sp.TSBY-70.Strain S1-1 grew well either in high nitrate or high nitrite conditions with a removal of 100% nitrate or 63.50% nitrite,and the total nitrogen removal rates could reach to 46.48% and 31.89%,respectively.The results indicated that nitrate was mainly reduced in its logarithmic growth phase with a very low leve1 accumulation of nitrite,suggesting that the aerobic denitrification process of strain S1-1 occurred mainly in this phase.The GC-MS results showed that N 2 O was formed as the major intermediate during the aerobic denitrifying process of strain S1-1.Finally,factors affecting the growth of strain S1-1 and its aerobic denitrifying ability were also investigated.Results showed that the optimum aerobic denitrification conditions for strain S1-1 were sodium succinate as carbon source,C/N ratio15,salinity 10 g/L NaCl,incubation temperature 20°C and initial pH 6.5.展开更多
基金The Important National Science&Technology Specific Projects under contract No.2011ZX8001-003the National Natural Science Fundation of China under contract No.40706053Chinese Polar Environment Comprehensive Investigation&Assessment Programs under contract No.CHINARE2017-01-05
文摘B-3 exopolysaccharide is extracted from the Antarctic psychrophilic bacterium Psychrobacter sp. B-3. We have previously shown that it activates macrophages and affects their immunoregulatory activities. To determine what genes are affected during this process, we detected the genes differentially expressed in cells of RAW264.7 macrophages treated with B-3 exopolysaccharide by transcriptomic analysis. B-3 exopolysaccharide treatment caused differential expression of 420 genes, of which 178 were up-regulated and 242 were down-regulated. These genes were shown to be involved in many aspects of cell function, mainly metabolism and immunity. Genes were enriched in multiple immune-related pathways, and the most significantly enriched genes were involved in antigen processing and presentation pathways. The pathway in which differentially expressed genes were the most significantly enriched was the metabolic pathway; specifically, the expression of many metabolic enzyme genes was altered by B-3 exopolysaccharide treatment. Additionally, the genes involved in metabolisms of amino acids, carbohydrates, lipids and nucleotides, varied to certain degrees. B-3 exopolysaccharide, therefore, appears to directly affect the immune function of RAW264.7 macrophages as an immunostimulant, or to indirectly change intracellular metabolism. This is the first study to determine the effect of an Antarctic psychrophilic bacterial exopolysaccharide on RAW264.7 macrophages. Our findings provide an important reference for research into the regulation of macrophage immune function by different polysaccharides.
基金supported by the Korea Polar Research Institute(Grant nos.PE08050 and PE13240)
文摘Random mutagenesis is commonly used to study gene function. The screening of mutants exhibiting specific pheno- types assists in the identification of phenotype-related genes. In the current study, we isolated Antarctic bacteria, and developed a transposon Tn5 mutagenesis system. A total of 26 strains were isolated from seawater and freshwater near Antarctic King Sejong Research Station, King George Island. Six Psychrobacter strains were identified as psychrophilic, with optimal growth tempera- tures of 10~C or 15~C Psychrobacter cryohalolentis PAMC 21807 with a high growth rate at 4~C was selected for transposon mutagenesis. Tri-parental conjugation with a plasmid containing Tn5 produced 13 putative recombinants containing the selectable marker. Genomic Southern hybridization confirmed Tn5 existed as episomes for seven recombinants, and for a single recombinant, Tn5 was integrated into the genome of Psychrobacter cryohalolentis PAMC 21807. The result indicates that the mutagenesis method, although successful, has a relatively low rate. The psychrophilic bacteria isolated in this study may be a useful resource for studying cold adaptation mechanisms, and the mutagenesis method can be applied to genetic analysis.
基金The National Natural Science Foundation of China under contract No.41176174the Chinese Polar Environment Comprehensive Investigation and Assessment Program under contract No.CHINARE 2014-03-05the Public Science and Technology Funds for Ocean Projects under contract No.201205020-5
文摘The key functional genes involved in temperature adaption of the Antarctic psychrotrophic bacterium Psychrobacter sp. G. were identified by transcriptomic sequencing. We analyzed the global transcriptional profile of Psychrobacter sp. G under cold stress（0°C） and heat stress（30°C）, with the optimal growth temperature 20°C as the control. There were large alterations of the transcriptome profile, including significant upregulation of 11 and 12 transcripts as well as significant downregulation of 47 and 42 transcripts in the cold and heat stress groups, respectively, compared to the control. The expression of various genes encoding enzymes and transcriptional regulators, including Pfp I and Tet R family transcriptional regulators under heat stress, as well as the expression of DEAD/DEAH box helicase and the Icl R family of transcriptional regulators under cold stress, were upregulated significantly. The expression of several genes, most affiliated with Ton Bdependent receptor and siderophore receptor, was downregulated significantly under both heat and cold stress. Many of the genes associated with the metabolism of fatty acid and ABC transporters were regulated differentially under different temperature stress. The results of this survey of transcriptome and temperature stress-relevant genes contribute to our understanding of the stress-resistant mechanism in Antarctic bacteria.
基金supported financially by the National Natural Science Foundation of China (Grant no.41176174)
文摘Abstract Heat shock proteins （Hsps）, produced by organisms under high temperature stimulation, play important roles in protein folding, translocation, and refolding/degradati0n. In this study, we investigated the expression level of the GrpE Hsp gene Hsp845 of Psychrobacter sp. G under different temperature and salinity stresses by quantitative real-time PCR and western blotting, respectively. At both transcriptional and translational levels, Hsp845 gene expression was induced by high temperature （30~C） and inhibited by low temperatures （0~C and 10~C）. Hsp845 expression was also induced both by the absence of salt （0%0） and high salinity （90%0 and 120%o） at the transcriptional level, but was only induced by high salinity （90%0 and 120%o） at the translational level. In a combined stress treatment, Hsp845 was more sensitive to high temperature than to salinity at both transcriptional and translational levels. The increase in the translational-level expression of Hsp845 lagged behind that at the transcriptional level, and Hsp845 maximum expression was also higher at the transcriptional than at the translational level. In the absence of salt, transcriptional- and translational-level expressions exhibited opposite patterns, suggesting that the underlying mechanism requires further study.
文摘Psychrobacter species are gram-negative bacteria in the Moraxellaceae family.These bacteria are considered rare opportunistic human pathogens,and the infection sites include blood,cerebral spinal fluid,wounds,urine,the ears,and the eyes.Few cases of human infection by these species have been described previously.We report a case of a 10-year-old boy with postneurosurgical bacteremia due to Psychrobacter sanguinis infection.This infection was difficult to identify using routine biochemical phenotypical tests.Sequencing of 16S rRNA was performed to identify this pathogen.The patient was successfully treated with antibiotics.In conclusion,P.sanguinis infections are rare but should be considered when cultures remain negative for common pathogens.
基金supported by the Knowledge Innova-tion Program of the Chinese Academy of Sciences(No.KJCX2-YW-L08)
文摘A psychrophilic aerobic denitrifying bacterium,strain S1-1,was isolated from a biological aerated filter conducted for treatment of recirculating water in a marine aquaculture system.Strain S1-1 was preliminarily identified as Psychrobacter sp.based on the analysis of its 16S rRNA gene sequence,which showed 100% sequence similarity to that of Psychrobacter sp.TSBY-70.Strain S1-1 grew well either in high nitrate or high nitrite conditions with a removal of 100% nitrate or 63.50% nitrite,and the total nitrogen removal rates could reach to 46.48% and 31.89%,respectively.The results indicated that nitrate was mainly reduced in its logarithmic growth phase with a very low leve1 accumulation of nitrite,suggesting that the aerobic denitrification process of strain S1-1 occurred mainly in this phase.The GC-MS results showed that N 2 O was formed as the major intermediate during the aerobic denitrifying process of strain S1-1.Finally,factors affecting the growth of strain S1-1 and its aerobic denitrifying ability were also investigated.Results showed that the optimum aerobic denitrification conditions for strain S1-1 were sodium succinate as carbon source,C/N ratio15,salinity 10 g/L NaCl,incubation temperature 20°C and initial pH 6.5.
