Response surface methodology (RSM) was employed to optimize the medium composition and culture conditions for the production of alkaline proteases by Bacillus mojavensis A21 on uncommon substrates: chickpea (CF) and f...Response surface methodology (RSM) was employed to optimize the medium composition and culture conditions for the production of alkaline proteases by Bacillus mojavensis A21 on uncommon substrates: chickpea (CF) and faba bean (FF) flours. A significant positive influence of temperature, CF, FF, incubation time and inoculums size on the protease production was evaluated by Plackett Burman Design. Among these, CF was the most influential factor. The enhancement of protease to 9127 U/ml was achieved with the optimization procedure on the medium composed of (g/l): CF, 40;FF 30, NaCl 2.0;KH2PO4 1;K2HPO4 1;CaCl2, 0.1;MgSO4 0.1. The cultures were conducted for 72 hours with an IS of 2%, at 30°C, an agitation speed of 150 rpm and an initial pH of 8.0. More interestingly, the optimization was accomplished using two cheap and local fermentation substrates, CF and FF, which could result in a significant reduction in the cost of medium constituents. The maximum alkaline protease production was 9127 U/ml after 72 h of incubation and showed 5-fold increase in protease production over the initial level.展开更多
Statistical experimental designs were used to optimize the process of phenol degradation by Candida tropicalis Z-04, isolated from phenol-degrading aerobic granules. The most important factors influencing phenol degra...Statistical experimental designs were used to optimize the process of phenol degradation by Candida tropicalis Z-04, isolated from phenol-degrading aerobic granules. The most important factors influencing phenol degradation （p 〈 0.05）, as identified by a two-level Plackett-Burman design with 11 variables, were yeast extract, phenol, inoculum size, and temperature. Steepest ascent method was undertaken to determine the optimal regions of these four significant factors. Central composite design （CCD） and response surface analysis were adopted to further investigate the mutual interactions between these variables and to identify their optimal values that would generate maximum phenol degradation. The analysis results indicated that interactions between yeast extract and temperature, phenol and temperature, inocuhim size and temperature affected the response variable （phenol degradation） significantly. The predicted results showed that the maximum removal efficiency of phenol （99.10%） could be obtained under the optimum conditions of yeast extract 0.41 g/L, phenol 1.03 g/L, inoculum size 1.43% （V/V） and temperature 30.04℃. These predicted values were further verified by validation experiments. The excellent correlation between predicted and experimental values confirmed the validity and practicability of this statistical optimum strategy. This study indicated the excellent ability of C. tropicalis Z-04 in degrading high-strength phenol. Optimal conditions obtained in this experiment laid a solid foundation for further use of this microorganism in the treatment of highstrength phenol effluents.展开更多
文摘Response surface methodology (RSM) was employed to optimize the medium composition and culture conditions for the production of alkaline proteases by Bacillus mojavensis A21 on uncommon substrates: chickpea (CF) and faba bean (FF) flours. A significant positive influence of temperature, CF, FF, incubation time and inoculums size on the protease production was evaluated by Plackett Burman Design. Among these, CF was the most influential factor. The enhancement of protease to 9127 U/ml was achieved with the optimization procedure on the medium composed of (g/l): CF, 40;FF 30, NaCl 2.0;KH2PO4 1;K2HPO4 1;CaCl2, 0.1;MgSO4 0.1. The cultures were conducted for 72 hours with an IS of 2%, at 30°C, an agitation speed of 150 rpm and an initial pH of 8.0. More interestingly, the optimization was accomplished using two cheap and local fermentation substrates, CF and FF, which could result in a significant reduction in the cost of medium constituents. The maximum alkaline protease production was 9127 U/ml after 72 h of incubation and showed 5-fold increase in protease production over the initial level.
基金supported by the National Natural Science Foundation of China (No.50778110)
文摘Statistical experimental designs were used to optimize the process of phenol degradation by Candida tropicalis Z-04, isolated from phenol-degrading aerobic granules. The most important factors influencing phenol degradation （p 〈 0.05）, as identified by a two-level Plackett-Burman design with 11 variables, were yeast extract, phenol, inoculum size, and temperature. Steepest ascent method was undertaken to determine the optimal regions of these four significant factors. Central composite design （CCD） and response surface analysis were adopted to further investigate the mutual interactions between these variables and to identify their optimal values that would generate maximum phenol degradation. The analysis results indicated that interactions between yeast extract and temperature, phenol and temperature, inocuhim size and temperature affected the response variable （phenol degradation） significantly. The predicted results showed that the maximum removal efficiency of phenol （99.10%） could be obtained under the optimum conditions of yeast extract 0.41 g/L, phenol 1.03 g/L, inoculum size 1.43% （V/V） and temperature 30.04℃. These predicted values were further verified by validation experiments. The excellent correlation between predicted and experimental values confirmed the validity and practicability of this statistical optimum strategy. This study indicated the excellent ability of C. tropicalis Z-04 in degrading high-strength phenol. Optimal conditions obtained in this experiment laid a solid foundation for further use of this microorganism in the treatment of highstrength phenol effluents.
