The study of microbial hydrocarbons removal is of great importance for the development of future bioremediation strategies.In this study,we evaluated the removal of a gaseous mixture containing toluene,m-xylene,ethylb...The study of microbial hydrocarbons removal is of great importance for the development of future bioremediation strategies.In this study,we evaluated the removal of a gaseous mixture containing toluene,m-xylene,ethylbenzene,cyclohexane,butane,pentane,hexane and heptane in aerated stirred bioreactors inoculated with Rhodococcus erythropolis and operated under non-sterile conditions.For the real-time measurement of hydrocarbons,a novel systematic approachwas implemented using Selected-Ion Flow TubeMass Spectrometry(SIFTMS).The effect of the carbon source(~9.5 ppmv)on(i)the bioreactors’performance(BR1:dosed with only cyclohexane as a single hydrocarbon versus BR2:dosed with a mixture of the 8 hydrocarbons)and(ii)the evolution of microbial communities over time were investigated.The results showed that cyclohexane reached a maximum removal efficiency(RE)of 53%±4%in BR1.In BR2,almost complete removal of toluene,m-xylene and ethylbenzene,being the most water-soluble and easy-to-degrade carbon sources,was observed.REs below 32%were obtained for the remaining compounds.By exposing the microbial consortium to only the five most recalcitrant hydrocarbons,REs between 45%±5%and 98%±1%were reached.In addition,we observed that airborne microorganisms populated the bioreactors and that the type of carbon source influenced the microbial communities developed.The abundance of species belonging to the genus Rhodococcus was below 10%in all bioreactors at the end of the experiments.This work provides fundamental insights to understand the complex behavior of gaseous hydrocarbon mixtures in bioreactors,along with a systematic approach for the development of SIFT-MS methods.展开更多
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
The high-molecular weight polycyclic aromatic hydrocarbons(PAHs) pyrene and typical long chain alkane nhexadecane are both difficult to degrade. In this study, n-hexadecane and pyrene degrading strain Rhodococcus sp. ...The high-molecular weight polycyclic aromatic hydrocarbons(PAHs) pyrene and typical long chain alkane nhexadecane are both difficult to degrade. In this study, n-hexadecane and pyrene degrading strain Rhodococcus sp. T1 was isolated from oil contaminated soil. Strain T1 could remove 90.81% n-hexadecane(2 vol%) and 42.79% pyrene(200 mg·L^(-1)) as a single carbon within 5 days, respectively. Comparatively, the degradation of pyrene increased to 60.63%, but the degradation of n-hexadecane decreased to 87.55% when these compounds were mixed. Additionally, identification and analysis of degradation metabolites of Rhodococcus sp. T1 in the above experiments showed that there were significant changes in alanine, methylamine, citric acid and heptadecanoic acid between sole and dual substrate degradation. The optimal conditions for degradation were then determined based on analysis of the pH, salinity, additional nutrient sources and liquid surface activity.Under the optimal conditions of pH 7.0, 35 °C, 0.5% NaCl, 5 mg·L^(-1) of yeast extract and 90 mg·L^(-1) of surfactant,the degradation increased in single or dual carbon sources. To our knowledge, this is the first study to discuss metabolite changes in Rhodococcus sp. T1 using sole substrate and dual substrate to enhance the long-chain alkanes and PAHs degradation potential.展开更多
基金supported by Ghent University through a special research grant(No.BOFSTG2019005701)The assistance provided by Ann Dirckx in the microbiology lab was greatly appreciated.Allan A.Alvarado-Alvarado thanks the European Commission under the Erasmus+EMJMD Program for funding his research at Ghent University(No.2017-1957/001-001-EMJMD).
文摘The study of microbial hydrocarbons removal is of great importance for the development of future bioremediation strategies.In this study,we evaluated the removal of a gaseous mixture containing toluene,m-xylene,ethylbenzene,cyclohexane,butane,pentane,hexane and heptane in aerated stirred bioreactors inoculated with Rhodococcus erythropolis and operated under non-sterile conditions.For the real-time measurement of hydrocarbons,a novel systematic approachwas implemented using Selected-Ion Flow TubeMass Spectrometry(SIFTMS).The effect of the carbon source(~9.5 ppmv)on(i)the bioreactors’performance(BR1:dosed with only cyclohexane as a single hydrocarbon versus BR2:dosed with a mixture of the 8 hydrocarbons)and(ii)the evolution of microbial communities over time were investigated.The results showed that cyclohexane reached a maximum removal efficiency(RE)of 53%±4%in BR1.In BR2,almost complete removal of toluene,m-xylene and ethylbenzene,being the most water-soluble and easy-to-degrade carbon sources,was observed.REs below 32%were obtained for the remaining compounds.By exposing the microbial consortium to only the five most recalcitrant hydrocarbons,REs between 45%±5%and 98%±1%were reached.In addition,we observed that airborne microorganisms populated the bioreactors and that the type of carbon source influenced the microbial communities developed.The abundance of species belonging to the genus Rhodococcus was below 10%in all bioreactors at the end of the experiments.This work provides fundamental insights to understand the complex behavior of gaseous hydrocarbon mixtures in bioreactors,along with a systematic approach for the development of SIFT-MS methods.
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 Basic Research Program of China("973" Program:2014CB745100)the National Natural Science Foundation of China(21576197)Tianjin Key Research&Development Program(16YFXTSF00460)
文摘The high-molecular weight polycyclic aromatic hydrocarbons(PAHs) pyrene and typical long chain alkane nhexadecane are both difficult to degrade. In this study, n-hexadecane and pyrene degrading strain Rhodococcus sp. T1 was isolated from oil contaminated soil. Strain T1 could remove 90.81% n-hexadecane(2 vol%) and 42.79% pyrene(200 mg·L^(-1)) as a single carbon within 5 days, respectively. Comparatively, the degradation of pyrene increased to 60.63%, but the degradation of n-hexadecane decreased to 87.55% when these compounds were mixed. Additionally, identification and analysis of degradation metabolites of Rhodococcus sp. T1 in the above experiments showed that there were significant changes in alanine, methylamine, citric acid and heptadecanoic acid between sole and dual substrate degradation. The optimal conditions for degradation were then determined based on analysis of the pH, salinity, additional nutrient sources and liquid surface activity.Under the optimal conditions of pH 7.0, 35 °C, 0.5% NaCl, 5 mg·L^(-1) of yeast extract and 90 mg·L^(-1) of surfactant,the degradation increased in single or dual carbon sources. To our knowledge, this is the first study to discuss metabolite changes in Rhodococcus sp. T1 using sole substrate and dual substrate to enhance the long-chain alkanes and PAHs degradation potential.
