CO2 fixation pathway of Caminibacter profundus, a chemolithoautotrophic e-Proteobacteria from deep-sea hydrothermal vent, was determined and characterized by genetic and enzymatic analyses. Gene expression of key enzy...CO2 fixation pathway of Caminibacter profundus, a chemolithoautotrophic e-Proteobacteria from deep-sea hydrothermal vent, was determined and characterized by genetic and enzymatic analyses. Gene expression of key enzymes for CO2 fixation in response to salinity, pH and O2 in Medium 829 were also investigated. The results demonstrate that C. profundus contained aclB, porA and oorA, the genes encoding key enzymes of reductive tricarboxylic acid （rTCA） cycle. However, genes fragments of cbbL and cbbMencoding key enzyme of Calvin cycle were not recovered. Key enzymatic activities of ATP citrate lyase （ACL）, pyruvate： ferredoxin oxidoreductase （POR） and 2-oxoglutarate： ferredoxin oxidoreductase （OOR） were also present in C. profun- dus. The combination of genetic and enzymatic analyses confirm that C. profundus adopted rTCA cycle for carbon assimilation. The results of aclB and oorA relative expressions of C. profundus demonstrate that the ranges of environmental factors for high genes expression were sea salt 3.0%-5.0% （optimum 3.0%）, pH 5.0-6.5（optimum pH 6.5）, anaerobic to microaerobic conditions （optimum 1.0% 02）. Gene expression pat- terns under different conditions show similar patterns with bacterial growth, revealing that key rTCA cycle genes provided molecular basis for bacterial growth and propagation. Our results suggest that C. profun- dus could regulate key genes of rTCA cycle for carbon assimilation and energy metabolism in response to environmental fluctuations in hydrothermal vent.展开更多
In this study, an endolytic alginate lyase, named Al163, was identified, cloned, and characterized from the Antarctic bacterium Pseudoalteromonas sp. NJ-21. Comparative sequence analysis showed that the predicted amin...In this study, an endolytic alginate lyase, named Al163, was identified, cloned, and characterized from the Antarctic bacterium Pseudoalteromonas sp. NJ-21. Comparative sequence analysis showed that the predicted amino acid sequence encoded by al163 belongs to the polysaccharide lyase 6(PL-6) family and has a molecular mass of about 80 kDa. Recombinant enzyme was purified by Ni-Sepharose affinity chromatography. Recombinant Al163 exhibited maximum activity(258 U/mg) at pH 7.0 and 40℃, and thermal stability assays showed retention of almost 90% activity after incubation at 30℃ for 30 min. Al163 activity was stimulated by Cd^(2+), Ca^(2+), Fe^(3+), and Mn^(2+), but inhibited by Cu^(2+), Si^(2+), Fe^(2+), and Ni^(2+). Thin-layer chromatographic analysis indicated that Al163 degraded sodium alginate, poly M, and poly G, generating disaccharides and trisaccharides as the final products. Only a few bacterial strains that produce a bifunctional alginate lyase have been reported. Our results indicate that recombinant Al163 exhibits broad substrate specificity and its products exhibit low degrees of polymerization. Both properties imply high potential for use of the enzyme in several industrial fields, including cosmetics and pharmaceuticals, based on the high demand for biologically active oligosaccharides.展开更多
A red pigment that has better biological properties is produced by marine bacterium strainS- 9801. The extraction methods, physicochemical and toxicity of the pigment have been studied. Dissolubility of pigment in the...A red pigment that has better biological properties is produced by marine bacterium strainS- 9801. The extraction methods, physicochemical and toxicity of the pigment have been studied. Dissolubility of pigment in the five organic solvent has been tested, and ethanol is optimally chosen for extraction. Physicochemical characteristics of this pigment was stable. The absorbance of the pigment solution was no losing when put under natural light for 10 days or treated by UV for 30 minutes, color of the pigment unchanged after 100℃ hythere for 1 h or 80 ℃ xerother for 2 h. The median lethal dose (LD_50) of the rat by celiac injection was 670.04 mg/kg and minimum lethal dose of oral was greater than 2 000 mg/kg.展开更多
Strain of Flavobacterium sp.(S-9801),was screened from 207 strains of marine bacteria isolated from the Bohai Sea continental shelf and the Zhujiang Estuary,for its red pigment production.The biological characteristic...Strain of Flavobacterium sp.(S-9801),was screened from 207 strains of marine bacteria isolated from the Bohai Sea continental shelf and the Zhujiang Estuary,for its red pigment production.The biological characteristics of strain S-9801 and culture conditions of pigment production have been checked out in this study. The color of the bacterial colony on 2216E medium was from coccineus to rose bengal. Optimum culture conditions were sodium chloride concentration(g/dm3),10～30;pH,3～8;temperature,25～28℃;tryptone and yeast extract as nitrogen sources and glucose as carbon source. Under optimum conditions,pigment accumulation started after 12 h,reaching a maximum rate of synthesis at 36 h.展开更多
Twenty-seven antarctic bacteria producing extracellular polysaccharide （EPS） were selected from 57 strains by staining technology. The effects of major environmental factors on the growth and EPS production of Pseud...Twenty-seven antarctic bacteria producing extracellular polysaccharide （EPS） were selected from 57 strains by staining technology. The effects of major environmental factors on the growth and EPS production of Pseudoalteromonas sp. S - 15 - 13 were investigated, and the EPS was separated and purified for characterization analysis. The results showed that the optimal conditions for the EPS production were culture period, 56 h; growth temperature, 8 ℃ ; carbon source, 1.0% glucose; NaCI concentration, 3.0% ; pH 6.0 - 7.0. The EPS was purified by cold ethanol precipitation, proteins removal, ion exchange chromatography and gel chromatography technology. The molecular mass of EPS - H was 62 kDa as determined by the high performance gel permeation chromatography. Its sugar composition was a homopolymer of marmose analyzed by gas chromatograph spectroscopy. After repeated freezing and thawing of the bacteria hiomass in the presence of EPS, the bacterial growth was much higher than that observed after freezing in the absence of EPS and the difference augmented with the increase of freeze-thaw cycles. It is hypothesized that the adaptation of Pseudoalteromonas sp. S- 15 - 13 to the antarctic marine conditions, characterized by low temperature, high NaCl concentration and repeated freeze-thaw cycles, might be related to the EPS production ability.展开更多
The effects of Nd^3＋ on the quality and quantity of volatile organic compounds （VOCs） in the leaves of Lycopersicon esculentum were studied. The results demonstrate that Nd^3＋ can increase the total amount of VOC ...The effects of Nd^3＋ on the quality and quantity of volatile organic compounds （VOCs） in the leaves of Lycopersicon esculentum were studied. The results demonstrate that Nd^3＋ can increase the total amount of VOC by 75% after treatment for 120 h, as compared with the control. Phyto-oxylipins, terpenoids and aromatic compounds were increased by 73%, 38% and 21%, respectively. （E）-2-hexenal, the most abundant constituent is increased by 74%, β- phellandrene and α-caryophyllene in terpenoids,展开更多
基金China Ocean Mineral Resources R&D Association under contract No. DYXM-115-02-2-19Basic Scientific Fund for National Public Research Institutes of China under contract No. 2011T04
文摘CO2 fixation pathway of Caminibacter profundus, a chemolithoautotrophic e-Proteobacteria from deep-sea hydrothermal vent, was determined and characterized by genetic and enzymatic analyses. Gene expression of key enzymes for CO2 fixation in response to salinity, pH and O2 in Medium 829 were also investigated. The results demonstrate that C. profundus contained aclB, porA and oorA, the genes encoding key enzymes of reductive tricarboxylic acid （rTCA） cycle. However, genes fragments of cbbL and cbbMencoding key enzyme of Calvin cycle were not recovered. Key enzymatic activities of ATP citrate lyase （ACL）, pyruvate： ferredoxin oxidoreductase （POR） and 2-oxoglutarate： ferredoxin oxidoreductase （OOR） were also present in C. profun- dus. The combination of genetic and enzymatic analyses confirm that C. profundus adopted rTCA cycle for carbon assimilation. The results of aclB and oorA relative expressions of C. profundus demonstrate that the ranges of environmental factors for high genes expression were sea salt 3.0%-5.0% （optimum 3.0%）, pH 5.0-6.5（optimum pH 6.5）, anaerobic to microaerobic conditions （optimum 1.0% 02）. Gene expression pat- terns under different conditions show similar patterns with bacterial growth, revealing that key rTCA cycle genes provided molecular basis for bacterial growth and propagation. Our results suggest that C. profun- dus could regulate key genes of rTCA cycle for carbon assimilation and energy metabolism in response to environmental fluctuations in hydrothermal vent.
基金Supported by the Public Science and Technology Research Funds Project of Ocean(No.201505026-4)the Chinese Polar Environment Comprehensive Investigation&Assessment Programs(No.CHINARE2016-01-05)+1 种基金the Basic Scientific Research Funds of First Institute of Oceanography,State Oceanic Administration(SOA)(No.2014T09)the Qingdao Applied Basic Research Project(No.14-2-4-14-jch)
文摘In this study, an endolytic alginate lyase, named Al163, was identified, cloned, and characterized from the Antarctic bacterium Pseudoalteromonas sp. NJ-21. Comparative sequence analysis showed that the predicted amino acid sequence encoded by al163 belongs to the polysaccharide lyase 6(PL-6) family and has a molecular mass of about 80 kDa. Recombinant enzyme was purified by Ni-Sepharose affinity chromatography. Recombinant Al163 exhibited maximum activity(258 U/mg) at pH 7.0 and 40℃, and thermal stability assays showed retention of almost 90% activity after incubation at 30℃ for 30 min. Al163 activity was stimulated by Cd^(2+), Ca^(2+), Fe^(3+), and Mn^(2+), but inhibited by Cu^(2+), Si^(2+), Fe^(2+), and Ni^(2+). Thin-layer chromatographic analysis indicated that Al163 degraded sodium alginate, poly M, and poly G, generating disaccharides and trisaccharides as the final products. Only a few bacterial strains that produce a bifunctional alginate lyase have been reported. Our results indicate that recombinant Al163 exhibits broad substrate specificity and its products exhibit low degrees of polymerization. Both properties imply high potential for use of the enzyme in several industrial fields, including cosmetics and pharmaceuticals, based on the high demand for biologically active oligosaccharides.
文摘A red pigment that has better biological properties is produced by marine bacterium strainS- 9801. The extraction methods, physicochemical and toxicity of the pigment have been studied. Dissolubility of pigment in the five organic solvent has been tested, and ethanol is optimally chosen for extraction. Physicochemical characteristics of this pigment was stable. The absorbance of the pigment solution was no losing when put under natural light for 10 days or treated by UV for 30 minutes, color of the pigment unchanged after 100℃ hythere for 1 h or 80 ℃ xerother for 2 h. The median lethal dose (LD_50) of the rat by celiac injection was 670.04 mg/kg and minimum lethal dose of oral was greater than 2 000 mg/kg.
文摘Strain of Flavobacterium sp.(S-9801),was screened from 207 strains of marine bacteria isolated from the Bohai Sea continental shelf and the Zhujiang Estuary,for its red pigment production.The biological characteristics of strain S-9801 and culture conditions of pigment production have been checked out in this study. The color of the bacterial colony on 2216E medium was from coccineus to rose bengal. Optimum culture conditions were sodium chloride concentration(g/dm3),10～30;pH,3～8;temperature,25～28℃;tryptone and yeast extract as nitrogen sources and glucose as carbon source. Under optimum conditions,pigment accumulation started after 12 h,reaching a maximum rate of synthesis at 36 h.
文摘Twenty-seven antarctic bacteria producing extracellular polysaccharide （EPS） were selected from 57 strains by staining technology. The effects of major environmental factors on the growth and EPS production of Pseudoalteromonas sp. S - 15 - 13 were investigated, and the EPS was separated and purified for characterization analysis. The results showed that the optimal conditions for the EPS production were culture period, 56 h; growth temperature, 8 ℃ ; carbon source, 1.0% glucose; NaCI concentration, 3.0% ; pH 6.0 - 7.0. The EPS was purified by cold ethanol precipitation, proteins removal, ion exchange chromatography and gel chromatography technology. The molecular mass of EPS - H was 62 kDa as determined by the high performance gel permeation chromatography. Its sugar composition was a homopolymer of marmose analyzed by gas chromatograph spectroscopy. After repeated freezing and thawing of the bacteria hiomass in the presence of EPS, the bacterial growth was much higher than that observed after freezing in the absence of EPS and the difference augmented with the increase of freeze-thaw cycles. It is hypothesized that the adaptation of Pseudoalteromonas sp. S- 15 - 13 to the antarctic marine conditions, characterized by low temperature, high NaCl concentration and repeated freeze-thaw cycles, might be related to the EPS production ability.
文摘The effects of Nd^3＋ on the quality and quantity of volatile organic compounds （VOCs） in the leaves of Lycopersicon esculentum were studied. The results demonstrate that Nd^3＋ can increase the total amount of VOC by 75% after treatment for 120 h, as compared with the control. Phyto-oxylipins, terpenoids and aromatic compounds were increased by 73%, 38% and 21%, respectively. （E）-2-hexenal, the most abundant constituent is increased by 74%, β- phellandrene and α-caryophyllene in terpenoids,
