[Objective] The aim was to study the optimization of bio-emulsifier production by Geobacillus sp.XS2 based on response surface methodology.[Method] Firstly,single factor experiment was conducted to find out the main m...[Objective] The aim was to study the optimization of bio-emulsifier production by Geobacillus sp.XS2 based on response surface methodology.[Method] Firstly,single factor experiment was conducted to find out the main medium components influencing bio-emulsifier production by Geobacillus sp.XS2,and then response surface model was established by using response surface methodology and Design-Expert 7.0,so as to optimize the fermentation medium for bio-emulsifier production by Geobacillus sp.XS2.[Result] Glucose,KH2PO4 and K2HPO4 were the main impact factors of bio-emulsifier production by Geobacillus sp.XS2,and its optimal fermentation medium was composed of 68 g/L glucose,2 g/L NaNO3,5.03 g/L KH2PO4,1.36 g/L K2HPO4,0.2 g/L MgSO4·7H2O,0.02 g/L FeSO4·7H2O,0.01 g/L CaCl2·2H2O and 2 ml microelement solution.Under the optimal conditions,the measured emulsifying activity of bio-emulsifier (67.0%) was close to predictive value (66.7%) and increased by 27% compared with previous value before optimization.[Conclusion] Response surface methodology was applicable to the optimization of fermentation medium of bio-emulsifier production by Geobacillus sp.XS2,and its optimal result was consistent with actual result.展开更多
Thermophilic microorganisms have always been an important part of the ecosystem,particularly in a hot environment,as they play a key role in nutrient recycling at high temperatures where most microorganisms cannot cop...Thermophilic microorganisms have always been an important part of the ecosystem,particularly in a hot environment,as they play a key role in nutrient recycling at high temperatures where most microorganisms cannot cope.While most of the thermophiles are archaea,thermophiles can also be found among some species of bacteria.These bacteria are very useful in the fundamental study of heat adaptation,and they are also important as potential sources of thermostable enzymes and metabolites.Recently,we have isolated a Gram-positive thermophilic bacterium,Geobacillus sp.TFV3 from a volcanic soil sample from Deception Island,Antarctica.This project was undertaken to analyze the genes of this thermophilic Antarctic bacterium and to determine the presence of thermal-stress adaptation proteins in its genome.The genome of Geobacillus sp.TFV3 was first purified,sequenced,assembled,and annotated.The complete genome was found to harbor genes encoding for useful thermal-stress adaptation proteins.The majority of these proteins were categorized under the family of molecular chaperone and heat shock protein.This genomic information could eventually provide insights on how the bacterium adapts itself towards high growth temperatures.展开更多
Thermostable SOD is a promising enzyme in biotechnological applications. In the present study, thermo-phileGeobacillussp.EPT3 was isolated from a deep-sea hydrothermal field in the East Pacific. A thermo-stable supero...Thermostable SOD is a promising enzyme in biotechnological applications. In the present study, thermo-phileGeobacillussp.EPT3 was isolated from a deep-sea hydrothermal field in the East Pacific. A thermo-stable superoxide dismutase （SOD） from this strain was purified to homogeneity by steps of fractional am-monium sulfate precipitation, DEAE-Sepharose chromatography, and Phenyl-Sepharose chromatography. SOD was purified 13.4 fold to homogeneity with a specific activity of 3 354 U/mg and 11.1% recovery. SOD fromGeobacillussp. EPT3 was of the Mn-SOD type, judged by the insensitivity of the enzyme to both KCN and H2O2. SOD was determined to be a homodimer with monomeric molecular mass of 26.0 kDa. It had high thermostability at 50＆#176;C and 60＆#176;C. At tested conditions,SOD was relatively stable in the presence of some inhibitors and denaturants, such asβ-mercaptoethanol （β-ME）, dithiothreitol （DTT）, phenylmethylsulfonyl fluoride （PMSF）, urea, and guanidine hydrochloride.Geobacillussp. EPT3 SOD showed striking stability across a wide pH range from 5.0 to 11.0. It could withstand denaturants of extremely acidic and alkaline conditions, which makes it useful in the industrial applications.展开更多
The aim of this study was to characterize lipases from two thermophilic bacteria, Geobacillus stearothermophilus (GS) and Anoxybacillus flavithermus (AF) in heat treated cell lysates. The pH optimum, pH stability, tem...The aim of this study was to characterize lipases from two thermophilic bacteria, Geobacillus stearothermophilus (GS) and Anoxybacillus flavithermus (AF) in heat treated cell lysates. The pH optimum, pH stability, temperature stability and substrate kinetics and specificity of the lipases were determined. Optimum activity of the lipase from GS (LGS) was observed at pH 7.5, and the optimum activity of the lipase from AF (LAF) was at pH 8.0. LGS was stable up to 70°C after 12 hrs while LAF was stable up to 90°C after 12 hrs. Both enzymes were stable at a pH range of 6 to 8 over 12 h at 4°C. LGS had a highest V<sub>max</sub><sub></sub> value of 22 mM·min<sup>-</sup><sup>1</sup>·mg<sup>-</sup><sup>1</sup> with p-nitrophenyl acetate while the lowest K<sub>m</sub><sub></sub> was 0.8 mM with p-nitrophenyl laurate. The highest V<sub>max</sub><sub></sub> of LAF was 2.5 mM·min<sup>-</sup><sup>1</sup>·mg<sup>-</sup><sup>1</sup> with p-nitrophenyl myristate, and the lowest K<sub>m</sub><sub></sub> was 0.4 mM with p-nitrophenyl octanoate. LGS preferentially hydrolyzed p-nitrophenyl acetate and p-nitrophenyl octanoate while LAF preferentially hydrolyzed p-nitrophenyl myristate and p-nitrophenyldodecanoate. Lipases from both GS and AF showed characteristics that would be beneficial in food processing.展开更多
A novel thermostable β-galactosidase gene, designated as GkGallA, from the thermophilic bacterium Geobacillus kaustophilus HTA426 was cloned and heterologously overexpressed in Escherichia coli（E, coli）. Based on t...A novel thermostable β-galactosidase gene, designated as GkGallA, from the thermophilic bacterium Geobacillus kaustophilus HTA426 was cloned and heterologously overexpressed in Escherichia coli（E, coli）. Based on the sequence analysis, GkGallA belongs to the glycosyl hydrolase family 1 that was the first β-galactosidase of bacterial origins expressed by us in this family. The apparent molecular weight of GkGallA determined by sodium deodecyl sulfate-polyacrylamide gel electrophoresis is 52000. It exhibited the highest activity toward p-nitrophenyl-β-D-galactopyranoside at pH 7.8 and 70℃ and displayed high thermal stability, Divalent cations are prerequisite for the activity of GKGallA, with the highest activity in the presence of Mn2＋. Moreover, the three-dimensional structure of GkGaI1A was modeled to speculate the structure of the catalytic residues and the reac- tion mechanism. The catalytic residues consisting of Glu166 and Glu355 were verified by site-directed mutagenesis.展开更多
Disinfection was investigated in high-density ozone produced by dielectric barrier discharge under atmospheric pressure. Disinfection was studied on three-dimensional carriers made of hydrophilic vinyl-polysiloxane im...Disinfection was investigated in high-density ozone produced by dielectric barrier discharge under atmospheric pressure. Disinfection was studied on three-dimensional carriers made of hydrophilic vinyl-polysiloxane impression material and granular acrylic resin used for oral surgery. Experimental results indicate disinfection of spore-forming bacteria: Geobacillus stearothermophilus and Bacillus atrophaeus, and selected species of opportunistic pathogens: Aspergillus niger, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Candida albicans.展开更多
基金Supported by Knowledge Innovation Project Group of Chinese Academy of Sciences (KZCX2-YW-Q05-05)
文摘[Objective] The aim was to study the optimization of bio-emulsifier production by Geobacillus sp.XS2 based on response surface methodology.[Method] Firstly,single factor experiment was conducted to find out the main medium components influencing bio-emulsifier production by Geobacillus sp.XS2,and then response surface model was established by using response surface methodology and Design-Expert 7.0,so as to optimize the fermentation medium for bio-emulsifier production by Geobacillus sp.XS2.[Result] Glucose,KH2PO4 and K2HPO4 were the main impact factors of bio-emulsifier production by Geobacillus sp.XS2,and its optimal fermentation medium was composed of 68 g/L glucose,2 g/L NaNO3,5.03 g/L KH2PO4,1.36 g/L K2HPO4,0.2 g/L MgSO4·7H2O,0.02 g/L FeSO4·7H2O,0.01 g/L CaCl2·2H2O and 2 ml microelement solution.Under the optimal conditions,the measured emulsifying activity of bio-emulsifier (67.0%) was close to predictive value (66.7%) and increased by 27% compared with previous value before optimization.[Conclusion] Response surface methodology was applicable to the optimization of fermentation medium of bio-emulsifier production by Geobacillus sp.XS2,and its optimal result was consistent with actual result.
基金funding support from the Ministry of Science,Technology,and Innovation(MOSTI),Malaysia,under the Antarctica Flagship Programme(Sub-Project 1:Grant no.FP1213E036)。
文摘Thermophilic microorganisms have always been an important part of the ecosystem,particularly in a hot environment,as they play a key role in nutrient recycling at high temperatures where most microorganisms cannot cope.While most of the thermophiles are archaea,thermophiles can also be found among some species of bacteria.These bacteria are very useful in the fundamental study of heat adaptation,and they are also important as potential sources of thermostable enzymes and metabolites.Recently,we have isolated a Gram-positive thermophilic bacterium,Geobacillus sp.TFV3 from a volcanic soil sample from Deception Island,Antarctica.This project was undertaken to analyze the genes of this thermophilic Antarctic bacterium and to determine the presence of thermal-stress adaptation proteins in its genome.The genome of Geobacillus sp.TFV3 was first purified,sequenced,assembled,and annotated.The complete genome was found to harbor genes encoding for useful thermal-stress adaptation proteins.The majority of these proteins were categorized under the family of molecular chaperone and heat shock protein.This genomic information could eventually provide insights on how the bacterium adapts itself towards high growth temperatures.
基金The National Natural Science Foundation of China under contract No.31371751the Science and Technology Program of Xiamen,China under contract No.201303120001the Foundation for Innovative Research Team of Jimei University,China under contract No.2010A006
文摘Thermostable SOD is a promising enzyme in biotechnological applications. In the present study, thermo-phileGeobacillussp.EPT3 was isolated from a deep-sea hydrothermal field in the East Pacific. A thermo-stable superoxide dismutase （SOD） from this strain was purified to homogeneity by steps of fractional am-monium sulfate precipitation, DEAE-Sepharose chromatography, and Phenyl-Sepharose chromatography. SOD was purified 13.4 fold to homogeneity with a specific activity of 3 354 U/mg and 11.1% recovery. SOD fromGeobacillussp. EPT3 was of the Mn-SOD type, judged by the insensitivity of the enzyme to both KCN and H2O2. SOD was determined to be a homodimer with monomeric molecular mass of 26.0 kDa. It had high thermostability at 50＆#176;C and 60＆#176;C. At tested conditions,SOD was relatively stable in the presence of some inhibitors and denaturants, such asβ-mercaptoethanol （β-ME）, dithiothreitol （DTT）, phenylmethylsulfonyl fluoride （PMSF）, urea, and guanidine hydrochloride.Geobacillussp. EPT3 SOD showed striking stability across a wide pH range from 5.0 to 11.0. It could withstand denaturants of extremely acidic and alkaline conditions, which makes it useful in the industrial applications.
文摘The aim of this study was to characterize lipases from two thermophilic bacteria, Geobacillus stearothermophilus (GS) and Anoxybacillus flavithermus (AF) in heat treated cell lysates. The pH optimum, pH stability, temperature stability and substrate kinetics and specificity of the lipases were determined. Optimum activity of the lipase from GS (LGS) was observed at pH 7.5, and the optimum activity of the lipase from AF (LAF) was at pH 8.0. LGS was stable up to 70°C after 12 hrs while LAF was stable up to 90°C after 12 hrs. Both enzymes were stable at a pH range of 6 to 8 over 12 h at 4°C. LGS had a highest V<sub>max</sub><sub></sub> value of 22 mM·min<sup>-</sup><sup>1</sup>·mg<sup>-</sup><sup>1</sup> with p-nitrophenyl acetate while the lowest K<sub>m</sub><sub></sub> was 0.8 mM with p-nitrophenyl laurate. The highest V<sub>max</sub><sub></sub> of LAF was 2.5 mM·min<sup>-</sup><sup>1</sup>·mg<sup>-</sup><sup>1</sup> with p-nitrophenyl myristate, and the lowest K<sub>m</sub><sub></sub> was 0.4 mM with p-nitrophenyl octanoate. LGS preferentially hydrolyzed p-nitrophenyl acetate and p-nitrophenyl octanoate while LAF preferentially hydrolyzed p-nitrophenyl myristate and p-nitrophenyldodecanoate. Lipases from both GS and AF showed characteristics that would be beneficial in food processing.
文摘A novel thermostable β-galactosidase gene, designated as GkGallA, from the thermophilic bacterium Geobacillus kaustophilus HTA426 was cloned and heterologously overexpressed in Escherichia coli（E, coli）. Based on the sequence analysis, GkGallA belongs to the glycosyl hydrolase family 1 that was the first β-galactosidase of bacterial origins expressed by us in this family. The apparent molecular weight of GkGallA determined by sodium deodecyl sulfate-polyacrylamide gel electrophoresis is 52000. It exhibited the highest activity toward p-nitrophenyl-β-D-galactopyranoside at pH 7.8 and 70℃ and displayed high thermal stability, Divalent cations are prerequisite for the activity of GKGallA, with the highest activity in the presence of Mn2＋. Moreover, the three-dimensional structure of GkGaI1A was modeled to speculate the structure of the catalytic residues and the reac- tion mechanism. The catalytic residues consisting of Glu166 and Glu355 were verified by site-directed mutagenesis.
文摘Disinfection was investigated in high-density ozone produced by dielectric barrier discharge under atmospheric pressure. Disinfection was studied on three-dimensional carriers made of hydrophilic vinyl-polysiloxane impression material and granular acrylic resin used for oral surgery. Experimental results indicate disinfection of spore-forming bacteria: Geobacillus stearothermophilus and Bacillus atrophaeus, and selected species of opportunistic pathogens: Aspergillus niger, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Candida albicans.
