The favorable microbes for the asymmetric reduction of prochiral aromatic ketones was isolated from soil using acetophenone as the sole carbon source,when the asymmetric reduction of acetophenone(ACP)to chiral a-phene...The favorable microbes for the asymmetric reduction of prochiral aromatic ketones was isolated from soil using acetophenone as the sole carbon source,when the asymmetric reduction of acetophenone(ACP)to chiral a-phenethyl alcohol(PEA)was chosen as the model reaction.Two microbe strains with excellent catalytic activity were obtained.They were Geotrichum candidum and Pichia pastoris identified by bacteria identification.The product of the asymmetric reduction of ACP catalyzed by Pichia pastoris was mainly R-PEA and that by Geotrichum candidum was mainly S-PEA.The yield and enantiomeric excesses(e.e.)could respectively reach 75%and 90%for Pichia pastoris,and 80%and 70%for Geotrichum candidum,much higher than those catalyzed by baker’s yeast.展开更多
Primary oil recovery is the first stage of hydrocarbon production in which a reservoir uses its natural energy to force hydrocarbon to its wellbore.Secondary oil recovery comes to play when hydrocarbons can no longer ...Primary oil recovery is the first stage of hydrocarbon production in which a reservoir uses its natural energy to force hydrocarbon to its wellbore.Secondary oil recovery comes to play when hydrocarbons can no longer be further produced by natural means.The purpose of secondary recovery is to maintain reservoir pressure so as to displace hydrocarbons toward the wellbore.Both primary and secondary recovery processes cannot displace more than 50%of the available hydrocarbons in a reservoir.The remaining hydrocarbons are further recovered through Tertiary/Enhanced Oil Recovery techniques.According to literature,microbial enhanced oil recovery has been identified as a tertiary method used to improve the efficiency of hydrocarbon production from reservoirs.Microbial enhanced oil recovery is a feasible reservoir technology,which has not been widely used in the oil and gas industry owing to the attainment of the requisite reservoir conditions such as temperature within which microbes can thrive.Literature has shown that thermotolerant microbes can withstand optimum temperatures of 50e90℃,while deep and ultra-deep hydrocarbon reservoir temperatures are often above 100℃.This study identifies some isolated thermotolerant microbes from a sandstone reservoir that can withstand temperatures as high as 110℃via conventional methods and molecular analysis.The identified thermotolerant petroleum microbes:Bacillus amyloliquefaciens(A)and Bacillus nealsonii(B)were used to enhance oil recovery from a reservoir.The results showed that the microbial species A and B at a confined pressure of 3.0 MPa and temperature of 27℃,gave 46.4%and 48.6%oil recoveries,respectively,which is comparably higher than the value(26.9%)obtained for the water flooded samples.At temperatures of 80,90,100,110 and 120℃,the oil recovery results show that the recovery factor(55.2%e64.1%)of species B were higher compared to the range(46.7e57.5%)recorded for species A.At the onset of the core flooding experiments,there was an initial increment in oil recovery factor as the temperature increased from 80 to 110℃,whereas,it remained constant within 110e120℃.This trend coincides with the drop in the thermal resistance exhibited by the microbes when exposed to such conditions.The cumulative oil production from the commercial Eclipse simulation closely matched those of the experiment results,whereas,the slight difference can be attributed to the adjustment of the simulation input parameters.The experimental results show that species B can be used to enhance oil recovery at reservoir temperature conditions above 100℃.展开更多
Organophosphate compounds are widely used in agricultural activities to optimize food production. Contaminationof field soil by these compounds may result in detrimental effects on soil biota. The aim of the present s...Organophosphate compounds are widely used in agricultural activities to optimize food production. Contaminationof field soil by these compounds may result in detrimental effects on soil biota. The aim of the present studywas to isolate microorganisms from field soils and evaluate the strains on ability to degrade organophosphates as singleisolate and as a consortium. Isolated strains were identified using both biochemical and molecular techniques.Results revealed that, out of the 46 isolated strains, three isolates herein referred to as S6, S36 and S37 showed an averagediazinon degradation rate of 76.4%, 76.7% and 76.8% respectively, of the initial dose (50 ppm) within 11 daysof incubation in mineral medium. Notably, isolates S36 and S37 were more effective than S6 in degrading diazinonby 40% in soil aliquot after 11 days and therefore were evaluated on biochemical reactions and molecular identification.The isolates showed variable biochemical characteristics. However, both isolates possessed catalase enzyme,but lacked oxidase enzyme. Molecular characterization showed that, the closest species for S36 and S37 were Priestiamegaterium and P. arybattia, respectively, based on 16S rRNA gene similarity (> 99%). Combination of the strainsincreased diazinon degradation ability by 45% compared to single strain treatment. Chlorpyrifos was the most highlydegraded organophosphate, compared to phorate and cadusafos. Therefore it is expected that the pesticide-degradingbacteria could be a solution to soil health improvement and contribution to the production of safe agriculturalproducts.展开更多
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20050335131)Wuhan Youth Scientist Dawn Foundation(200750731288)Natural Science Foundation of Wuhan University of Science and Technology(2005XY15).
文摘The favorable microbes for the asymmetric reduction of prochiral aromatic ketones was isolated from soil using acetophenone as the sole carbon source,when the asymmetric reduction of acetophenone(ACP)to chiral a-phenethyl alcohol(PEA)was chosen as the model reaction.Two microbe strains with excellent catalytic activity were obtained.They were Geotrichum candidum and Pichia pastoris identified by bacteria identification.The product of the asymmetric reduction of ACP catalyzed by Pichia pastoris was mainly R-PEA and that by Geotrichum candidum was mainly S-PEA.The yield and enantiomeric excesses(e.e.)could respectively reach 75%and 90%for Pichia pastoris,and 80%and 70%for Geotrichum candidum,much higher than those catalyzed by baker’s yeast.
文摘Primary oil recovery is the first stage of hydrocarbon production in which a reservoir uses its natural energy to force hydrocarbon to its wellbore.Secondary oil recovery comes to play when hydrocarbons can no longer be further produced by natural means.The purpose of secondary recovery is to maintain reservoir pressure so as to displace hydrocarbons toward the wellbore.Both primary and secondary recovery processes cannot displace more than 50%of the available hydrocarbons in a reservoir.The remaining hydrocarbons are further recovered through Tertiary/Enhanced Oil Recovery techniques.According to literature,microbial enhanced oil recovery has been identified as a tertiary method used to improve the efficiency of hydrocarbon production from reservoirs.Microbial enhanced oil recovery is a feasible reservoir technology,which has not been widely used in the oil and gas industry owing to the attainment of the requisite reservoir conditions such as temperature within which microbes can thrive.Literature has shown that thermotolerant microbes can withstand optimum temperatures of 50e90℃,while deep and ultra-deep hydrocarbon reservoir temperatures are often above 100℃.This study identifies some isolated thermotolerant microbes from a sandstone reservoir that can withstand temperatures as high as 110℃via conventional methods and molecular analysis.The identified thermotolerant petroleum microbes:Bacillus amyloliquefaciens(A)and Bacillus nealsonii(B)were used to enhance oil recovery from a reservoir.The results showed that the microbial species A and B at a confined pressure of 3.0 MPa and temperature of 27℃,gave 46.4%and 48.6%oil recoveries,respectively,which is comparably higher than the value(26.9%)obtained for the water flooded samples.At temperatures of 80,90,100,110 and 120℃,the oil recovery results show that the recovery factor(55.2%e64.1%)of species B were higher compared to the range(46.7e57.5%)recorded for species A.At the onset of the core flooding experiments,there was an initial increment in oil recovery factor as the temperature increased from 80 to 110℃,whereas,it remained constant within 110e120℃.This trend coincides with the drop in the thermal resistance exhibited by the microbes when exposed to such conditions.The cumulative oil production from the commercial Eclipse simulation closely matched those of the experiment results,whereas,the slight difference can be attributed to the adjustment of the simulation input parameters.The experimental results show that species B can be used to enhance oil recovery at reservoir temperature conditions above 100℃.
文摘Organophosphate compounds are widely used in agricultural activities to optimize food production. Contaminationof field soil by these compounds may result in detrimental effects on soil biota. The aim of the present studywas to isolate microorganisms from field soils and evaluate the strains on ability to degrade organophosphates as singleisolate and as a consortium. Isolated strains were identified using both biochemical and molecular techniques.Results revealed that, out of the 46 isolated strains, three isolates herein referred to as S6, S36 and S37 showed an averagediazinon degradation rate of 76.4%, 76.7% and 76.8% respectively, of the initial dose (50 ppm) within 11 daysof incubation in mineral medium. Notably, isolates S36 and S37 were more effective than S6 in degrading diazinonby 40% in soil aliquot after 11 days and therefore were evaluated on biochemical reactions and molecular identification.The isolates showed variable biochemical characteristics. However, both isolates possessed catalase enzyme,but lacked oxidase enzyme. Molecular characterization showed that, the closest species for S36 and S37 were Priestiamegaterium and P. arybattia, respectively, based on 16S rRNA gene similarity (> 99%). Combination of the strainsincreased diazinon degradation ability by 45% compared to single strain treatment. Chlorpyrifos was the most highlydegraded organophosphate, compared to phorate and cadusafos. Therefore it is expected that the pesticide-degradingbacteria could be a solution to soil health improvement and contribution to the production of safe agriculturalproducts.
