[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
从西藏搭格架铯硅华矿床区热泉中分离培养高温菌T4-1,并进行了格兰氏染色、显微镜观察、室内温度实验、16SrRNA基因分析等。结果表明,T4-1为杆状菌,格兰氏染色阳性,其生长范围为45-80℃,最适生长温度70℃。16SrRNA基因分析结果表明,该...从西藏搭格架铯硅华矿床区热泉中分离培养高温菌T4-1,并进行了格兰氏染色、显微镜观察、室内温度实验、16SrRNA基因分析等。结果表明,T4-1为杆状菌,格兰氏染色阳性,其生长范围为45-80℃,最适生长温度70℃。16SrRNA基因分析结果表明,该菌株属于地芽孢杆菌属（Geobacillus）,在发育树上,T4-1菌株与高温烷烃地芽孢杆菌（Geobacillus the rmoleovorans）非常近。本研究为进一步开展西藏高温微生物资源以及微生物参与成矿作用的研究提供了首例。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
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.
文摘从西藏搭格架铯硅华矿床区热泉中分离培养高温菌T4-1,并进行了格兰氏染色、显微镜观察、室内温度实验、16SrRNA基因分析等。结果表明,T4-1为杆状菌,格兰氏染色阳性,其生长范围为45-80℃,最适生长温度70℃。16SrRNA基因分析结果表明,该菌株属于地芽孢杆菌属（Geobacillus）,在发育树上,T4-1菌株与高温烷烃地芽孢杆菌（Geobacillus the rmoleovorans）非常近。本研究为进一步开展西藏高温微生物资源以及微生物参与成矿作用的研究提供了首例。
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.
