Biologically produced surfactants （SACs） can mobilize and solubilize non-aqueous phase liquids （NAPL） adsorbed onto soil constituents. The interest in microbial surfactants has increased during recent years due to...Biologically produced surfactants （SACs） can mobilize and solubilize non-aqueous phase liquids （NAPL） adsorbed onto soil constituents. The interest in microbial surfactants has increased during recent years due to their lower toxicity, higher biodegradability, selectivity and specific activity under extreme conditions than synthetic SACs. Main output of the project represents preparation of this yeast biosurfactant intended for washing of matrices contaminated by NAPL. The influence of cultivation media composition on biosurfactant production was studied and basic properties （critical micelle concentration （CMC）, minimum surface tension） of isolated biosurfactants were compared with properties of synthetic surfactant with surface tension measurement. The interracial tension of the systems containing aqueous solutions of different concentrations and non-polar substances was measured with petroleum compounds （kerosene Jet A-l）, aromatic and aliphatic hydrocarbons （represented by toluene and hexane）. The solution of biosurfactant Yarrowia lipolytica （YAR） in the concentration range of 0-500 mg/L reduced interracial tension by 80% in all representative systems with model contaminants; biosurfactant Candida bombicola （CAN） was less efficient. Solubilization properties were proved with toluene and hexachlorocyclohexane （HCH） isomers alpha and gamma, and effective concentration of biosurfactants was determined as 100 mg/L for toluene and HCH. SACs produced by lipophilic yeast with non-toxic and non-pathogenic status （Yarrowia lipolytica, Candida sp., etc.） seem to be very promising. The results obtained will be used for the application of biosurfactants in the clean-up technologies as agents for the mobilization of non-polar contaminants as well as for stimulation of bioremediation processes.展开更多
为有效利用固态废弃毕赤酵母,高效发酵生产丁酸,建立了以80 g/L玉米淀粉为基础培养基、以废弃毕赤酵母处理液为高效有机氮源,连续补加葡萄糖的丁酸发酵工艺。7 L厌氧发酵罐下,发酵20h,先以1∶4的比例添加250~400 g/L规格的废弃酵母处理...为有效利用固态废弃毕赤酵母,高效发酵生产丁酸,建立了以80 g/L玉米淀粉为基础培养基、以废弃毕赤酵母处理液为高效有机氮源,连续补加葡萄糖的丁酸发酵工艺。7 L厌氧发酵罐下,发酵20h,先以1∶4的比例添加250~400 g/L规格的废弃酵母处理液替代昂贵的发酵用复合培养基,再连续补加葡萄糖浓缩液。最终的丁酸质量浓度为45 g/L、得率为40%,丁酸占总酸的比率(butyric acid ratio over total organic acids,B/TA)≥0.90的较高水平。该工艺可以有效地利用来自于废弃酵母处理液中的氨基酸,提高细胞生长速度和浓度,增强丁酸合成所依赖的NADH再生速度,间接改善了丁酸发酵性能。与此同时,实现了废弃生物质的有效利用和资源化。展开更多
During spontaneous fermentation of light-flavor Baijiu,the microbial diversity decreased gradually.Lactic acid bacteria(LAB)and yeast predominated at the end of fermentation and showed a strong positive correlation wi...During spontaneous fermentation of light-flavor Baijiu,the microbial diversity decreased gradually.Lactic acid bacteria(LAB)and yeast predominated at the end of fermentation and showed a strong positive correlation with esters in Baijiu.Exploring the metabolic characteristics of LAB and interactions with yeast are important for revealing the mechanism of Baijiu fermentation.The carbon source utilization heatmap showed that Lactobacillus acetotolerans,Lactobacillus brevis,and Lactobacillus hilgardii could utilize various organic acids.Lactobacillus plantarum could utilize a variety of amino acids.The utilization efficiency of different substrates was supposed to be an important factor for different LAB species dynamics during fermentation.The effects of pH,temperature and ethanol on the esterase activity of LAB were further analyzed.The results showed that pH was the most significant factor on esterase activity,and all the strains showed the highest activity at pH 7.0.Principal component analysis indicated that co-culture of LAB and Saccharomyces cerevisiae could promote the formation of esters,and the co-culture of Lactobacillus acetotolerans or Leuconostoc mesenteroides with Pichia anomala could promote the production of esters and alcohols.LAB showed a weak inhibitory effect on the growth of yeast,whereas the growth of LAB was significantly inhibited by yeast in the co-culture system.The results of this work will broaden our knowledge regarding the esterase activity,carbon source utilization efficiency of LAB and interactions with predominant yeast,which will provide a theoretical basis for the dynamics of different LAB species and their effects on the flavor of Baijiu.展开更多
文摘Biologically produced surfactants （SACs） can mobilize and solubilize non-aqueous phase liquids （NAPL） adsorbed onto soil constituents. The interest in microbial surfactants has increased during recent years due to their lower toxicity, higher biodegradability, selectivity and specific activity under extreme conditions than synthetic SACs. Main output of the project represents preparation of this yeast biosurfactant intended for washing of matrices contaminated by NAPL. The influence of cultivation media composition on biosurfactant production was studied and basic properties （critical micelle concentration （CMC）, minimum surface tension） of isolated biosurfactants were compared with properties of synthetic surfactant with surface tension measurement. The interracial tension of the systems containing aqueous solutions of different concentrations and non-polar substances was measured with petroleum compounds （kerosene Jet A-l）, aromatic and aliphatic hydrocarbons （represented by toluene and hexane）. The solution of biosurfactant Yarrowia lipolytica （YAR） in the concentration range of 0-500 mg/L reduced interracial tension by 80% in all representative systems with model contaminants; biosurfactant Candida bombicola （CAN） was less efficient. Solubilization properties were proved with toluene and hexachlorocyclohexane （HCH） isomers alpha and gamma, and effective concentration of biosurfactants was determined as 100 mg/L for toluene and HCH. SACs produced by lipophilic yeast with non-toxic and non-pathogenic status （Yarrowia lipolytica, Candida sp., etc.） seem to be very promising. The results obtained will be used for the application of biosurfactants in the clean-up technologies as agents for the mobilization of non-polar contaminants as well as for stimulation of bioremediation processes.
文摘为有效利用固态废弃毕赤酵母,高效发酵生产丁酸,建立了以80 g/L玉米淀粉为基础培养基、以废弃毕赤酵母处理液为高效有机氮源,连续补加葡萄糖的丁酸发酵工艺。7 L厌氧发酵罐下,发酵20h,先以1∶4的比例添加250~400 g/L规格的废弃酵母处理液替代昂贵的发酵用复合培养基,再连续补加葡萄糖浓缩液。最终的丁酸质量浓度为45 g/L、得率为40%,丁酸占总酸的比率(butyric acid ratio over total organic acids,B/TA)≥0.90的较高水平。该工艺可以有效地利用来自于废弃酵母处理液中的氨基酸,提高细胞生长速度和浓度,增强丁酸合成所依赖的NADH再生速度,间接改善了丁酸发酵性能。与此同时,实现了废弃生物质的有效利用和资源化。
基金financially supported by Beijing Municipal Education Commission Science Project(No.KM202110020002)supported by the Open Project Program of the Key Laboratory of Brewing Molecular Engineering of China Light Industry(No.BME-202104).
文摘During spontaneous fermentation of light-flavor Baijiu,the microbial diversity decreased gradually.Lactic acid bacteria(LAB)and yeast predominated at the end of fermentation and showed a strong positive correlation with esters in Baijiu.Exploring the metabolic characteristics of LAB and interactions with yeast are important for revealing the mechanism of Baijiu fermentation.The carbon source utilization heatmap showed that Lactobacillus acetotolerans,Lactobacillus brevis,and Lactobacillus hilgardii could utilize various organic acids.Lactobacillus plantarum could utilize a variety of amino acids.The utilization efficiency of different substrates was supposed to be an important factor for different LAB species dynamics during fermentation.The effects of pH,temperature and ethanol on the esterase activity of LAB were further analyzed.The results showed that pH was the most significant factor on esterase activity,and all the strains showed the highest activity at pH 7.0.Principal component analysis indicated that co-culture of LAB and Saccharomyces cerevisiae could promote the formation of esters,and the co-culture of Lactobacillus acetotolerans or Leuconostoc mesenteroides with Pichia anomala could promote the production of esters and alcohols.LAB showed a weak inhibitory effect on the growth of yeast,whereas the growth of LAB was significantly inhibited by yeast in the co-culture system.The results of this work will broaden our knowledge regarding the esterase activity,carbon source utilization efficiency of LAB and interactions with predominant yeast,which will provide a theoretical basis for the dynamics of different LAB species and their effects on the flavor of Baijiu.
