Among 39 species of microbial strains,Rhodococcus sp.AS 4.1147 possessed the ability to selectively acetylate puerarin（1） at C-6 position of the glucosyl moiety.The structure of the acetylated product,6’’-O-acetyl...Among 39 species of microbial strains,Rhodococcus sp.AS 4.1147 possessed the ability to selectively acetylate puerarin（1） at C-6 position of the glucosyl moiety.The structure of the acetylated product,6’’-O-acetylpuerarin（2） was determined by the analysis of MS,NMR spectroscopic data.The isolated yield of 2 was 22.2%.展开更多
Inducing expression and the reaction characteristic of nitrile hydratase （NHase） from Rhodococcus sp. SHZ-1 were investigated. The results showed that the expression of NHase was greatly enhanced with the cooperatio...Inducing expression and the reaction characteristic of nitrile hydratase （NHase） from Rhodococcus sp. SHZ-1 were investigated. The results showed that the expression of NHase was greatly enhanced with the cooperation of acrylonitrile and ammonium chloride as inducer in the medium and the specific activity of NHase was increased of 44%. Then the temperature, pH, concentration of acrylonitrile and acrylamide were evaluated, which affected the activity and reaction characteristic of NHase. It was found that the temperature and concentration of acrylarnide were the most important factors for the catalyzation of NHase. The optimal catalysis temperature of NHase from Rhodococcus sp. SHZ-1 was 30℃, and the activation energy of the hydration of NHase was 90.2kJ·mol^-1 in the temperature range from 5℃ to 30℃. Kmof NHase was 0.095mol·L^-1 using acrylonitrile（AN） as substrate, and NHase activity was inhibited seriously when acrylonitrile concentration was up to 40g·L^-1, the substrate inhibition constant Ki is 0.283mol·L^-1. Moreover, the NHase from Rhodococcus sp. SHZ-1 had very strong tolerance to acrylamide, in which the final concentration of acrylamide reached to 642g·L^-1 and the residual activity of NHase still maintained 8.6% of the initial enzyme activity.展开更多
Co-contamination of diesel fuel and heavy metals can be challenging for microbial remediation due to the complex composition of the fuel and the inhibitory effect of heavy metals.There is an urgent need to study this ...Co-contamination of diesel fuel and heavy metals can be challenging for microbial remediation due to the complex composition of the fuel and the inhibitory effect of heavy metals.There is an urgent need to study this interaction to improve the pollutant removal efficiency in the Polar Regions.The growth of an Antarctic bacterium,Rhodococcus sp.was studied by comparing the growth at the logarithmic phase under the effect of selected heavy metals(Pb,Cr,As,Cd,Cu,Zn,Ni,Hg and Co).The selected heavy metals inhibited the growth of the Rhodococcus sp.on diesel fuel in an order from highest to lowest of:Hg>Zn>Cd>Cu>Co>Ni>As>Pb>Cr.Growth on diesel fuel co-contaminated with Hg and Zn were 2.95%and 5.71%,respectively compared to the no-metal control.A further experiment with various Zn concentrations was conducted.The specific growth rate of Rhodococcus sp.co-contaminated with different concentrations of Zn showed a correlation coefficient(r)of 0.916,and was modelled with an exponential decay model.Additional investigation is needed to determine the effect of low concentration of Zn on hydrocarbon degradation.It is important to understand the relationships between microbes,hydrocarbons and heavy metals,especially in the Polar Regions because this interaction might be promising in treating hydrocarbon-polluted sites containing heavy metals.The data and results also provide baseline tools of bioremediation processes at low temperatures and the knowledge of the ecological roles of Rhodococcus sp.in Antarctica.展开更多
基金The Science & Technology Project of Guangdong Province (Grant No. 2011A080403020)the Program for New Century Excellent Talents in University (Grant No. NCET-06-0155)
文摘Among 39 species of microbial strains,Rhodococcus sp.AS 4.1147 possessed the ability to selectively acetylate puerarin（1） at C-6 position of the glucosyl moiety.The structure of the acetylated product,6’’-O-acetylpuerarin（2） was determined by the analysis of MS,NMR spectroscopic data.The isolated yield of 2 was 22.2%.
基金Supported by the National Natural Science Foundation of China （No.20466002）, the Program for New Century Excellent Talents in University （NCET-04-089） and the Key Research Projects in the Uygur Autonomous Region of Xinjiang （No.200332109）.
文摘Inducing expression and the reaction characteristic of nitrile hydratase （NHase） from Rhodococcus sp. SHZ-1 were investigated. The results showed that the expression of NHase was greatly enhanced with the cooperation of acrylonitrile and ammonium chloride as inducer in the medium and the specific activity of NHase was increased of 44%. Then the temperature, pH, concentration of acrylonitrile and acrylamide were evaluated, which affected the activity and reaction characteristic of NHase. It was found that the temperature and concentration of acrylarnide were the most important factors for the catalyzation of NHase. The optimal catalysis temperature of NHase from Rhodococcus sp. SHZ-1 was 30℃, and the activation energy of the hydration of NHase was 90.2kJ·mol^-1 in the temperature range from 5℃ to 30℃. Kmof NHase was 0.095mol·L^-1 using acrylonitrile（AN） as substrate, and NHase activity was inhibited seriously when acrylonitrile concentration was up to 40g·L^-1, the substrate inhibition constant Ki is 0.283mol·L^-1. Moreover, the NHase from Rhodococcus sp. SHZ-1 had very strong tolerance to acrylamide, in which the final concentration of acrylamide reached to 642g·L^-1 and the residual activity of NHase still maintained 8.6% of the initial enzyme activity.
基金supported by Universiti Putra Malaysia attached to WLWJ(Grant no.GP-IPM/2013/9422700)。
文摘Co-contamination of diesel fuel and heavy metals can be challenging for microbial remediation due to the complex composition of the fuel and the inhibitory effect of heavy metals.There is an urgent need to study this interaction to improve the pollutant removal efficiency in the Polar Regions.The growth of an Antarctic bacterium,Rhodococcus sp.was studied by comparing the growth at the logarithmic phase under the effect of selected heavy metals(Pb,Cr,As,Cd,Cu,Zn,Ni,Hg and Co).The selected heavy metals inhibited the growth of the Rhodococcus sp.on diesel fuel in an order from highest to lowest of:Hg>Zn>Cd>Cu>Co>Ni>As>Pb>Cr.Growth on diesel fuel co-contaminated with Hg and Zn were 2.95%and 5.71%,respectively compared to the no-metal control.A further experiment with various Zn concentrations was conducted.The specific growth rate of Rhodococcus sp.co-contaminated with different concentrations of Zn showed a correlation coefficient(r)of 0.916,and was modelled with an exponential decay model.Additional investigation is needed to determine the effect of low concentration of Zn on hydrocarbon degradation.It is important to understand the relationships between microbes,hydrocarbons and heavy metals,especially in the Polar Regions because this interaction might be promising in treating hydrocarbon-polluted sites containing heavy metals.The data and results also provide baseline tools of bioremediation processes at low temperatures and the knowledge of the ecological roles of Rhodococcus sp.in Antarctica.
