[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
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
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.
