Production of high titers of an alkaline, extracellular and thermo-tolerant pectinase by a newly isolated yeast Pseudozyma sp. SPJ was carried out under solid state fermentation. Citrus peel, the inexpensive agro-indu...Production of high titers of an alkaline, extracellular and thermo-tolerant pectinase by a newly isolated yeast Pseudozyma sp. SPJ was carried out under solid state fermentation. Citrus peel, the inexpensive agro-industrial residue used as substrate, was experienced to be unsurpassed. Response surface methodology was conducted to optimize the culture conditions for Pseudozyma sp. SPJ for hyper production of pectinase. Plackett Burman design was applied to identify the most effective culture variables. Out of nine variables studied, incubation time, moisture content and ammonium sulfate were detected as most important. A full factorial Central Composite Design was used to optimize the levels of these variables, which resulted in 17-fold increase （71.19 IU/g to 1215.66 IU/g dry substrate） in the enzyme yield. The results of analysis of variance and multiple regression analysis implies that the effect of incubation time （p 〈 0.000） and moisture content （p 〈 0.018） is more than ammonium sulfate. And also the interaction of moisture content with ammonium sulfate （p 〈 0.002） is more significant.展开更多
Rate coefficients for energy-pooling （EP） collisions Rb（5PJ）＋ Cs（6P3/2） →Rb（5S1/2）＋ Cs（nlJ^1） have been measured. Atoms were excited to Rb（5PJ） and Cs（6P3/2） states using two single-mode diode lasers....Rate coefficients for energy-pooling （EP） collisions Rb（5PJ）＋ Cs（6P3/2） →Rb（5S1/2）＋ Cs（nlJ^1） have been measured. Atoms were excited to Rb（5PJ） and Cs（6P3/2） states using two single-mode diode lasers. To isolate the heteronuclear contribution in the fluorescence spectrum, a double-modulation technique has been adopted. The excited-atom density and spatial distribution are mapped by monitoring the absorption of a counterpropagating single-mode diode laser beam, tuned to Rb（5PJ→7S1/2） and Cs（6P3/2→8S1/2） transitions respectively, which could be translated parallelly to the pump beams. The excited atom densities are combined with the measured fluorescence ratios to determine cross sections for the EP processes. It was found that Rb（5P1/2）＋Cs（6Pa/2） collisions are more efficient than Rb（5Pa/2）＋Cs（6P3/2） collisions for populating Cs（4F5/2）, while the opposite is true for populating Cs（4F7/2）.展开更多
文摘Production of high titers of an alkaline, extracellular and thermo-tolerant pectinase by a newly isolated yeast Pseudozyma sp. SPJ was carried out under solid state fermentation. Citrus peel, the inexpensive agro-industrial residue used as substrate, was experienced to be unsurpassed. Response surface methodology was conducted to optimize the culture conditions for Pseudozyma sp. SPJ for hyper production of pectinase. Plackett Burman design was applied to identify the most effective culture variables. Out of nine variables studied, incubation time, moisture content and ammonium sulfate were detected as most important. A full factorial Central Composite Design was used to optimize the levels of these variables, which resulted in 17-fold increase （71.19 IU/g to 1215.66 IU/g dry substrate） in the enzyme yield. The results of analysis of variance and multiple regression analysis implies that the effect of incubation time （p 〈 0.000） and moisture content （p 〈 0.018） is more than ammonium sulfate. And also the interaction of moisture content with ammonium sulfate （p 〈 0.002） is more significant.
基金This work was partially supported by the National Natural Science Foundation of China under Grant No.10264004.
文摘Rate coefficients for energy-pooling （EP） collisions Rb（5PJ）＋ Cs（6P3/2） →Rb（5S1/2）＋ Cs（nlJ^1） have been measured. Atoms were excited to Rb（5PJ） and Cs（6P3/2） states using two single-mode diode lasers. To isolate the heteronuclear contribution in the fluorescence spectrum, a double-modulation technique has been adopted. The excited-atom density and spatial distribution are mapped by monitoring the absorption of a counterpropagating single-mode diode laser beam, tuned to Rb（5PJ→7S1/2） and Cs（6P3/2→8S1/2） transitions respectively, which could be translated parallelly to the pump beams. The excited atom densities are combined with the measured fluorescence ratios to determine cross sections for the EP processes. It was found that Rb（5P1/2）＋Cs（6Pa/2） collisions are more efficient than Rb（5Pa/2）＋Cs（6P3/2） collisions for populating Cs（4F5/2）, while the opposite is true for populating Cs（4F7/2）.
