该研究旨在通过筛选具有较高双乙酰生产能力的乳酸菌改善酸奶香气品质。从西藏灵菇中分离筛选具有较高双乙酰生产能力的乳酸菌菌株并结合形态学特征和16S r DNA基因序列分析技术鉴定,利用气相色谱-质谱联用技术(GC-MS)对比分析筛选菌株...该研究旨在通过筛选具有较高双乙酰生产能力的乳酸菌改善酸奶香气品质。从西藏灵菇中分离筛选具有较高双乙酰生产能力的乳酸菌菌株并结合形态学特征和16S r DNA基因序列分析技术鉴定,利用气相色谱-质谱联用技术(GC-MS)对比分析筛选菌株发酵酸奶和空白酸奶香气品质差异。结果显示,菌株1-33具有较高的双乙酰生产能力,经鉴定其为植物乳杆菌(Lactobacillus plantarum)。菌株1-33制备的酸奶中双乙酰含量是空白酸奶的近4倍,乙偶姻的含量(38.92mg/L)是空白酸奶(25.46mg/L)的1.5倍左右,乙醛产量与空白发酵酸奶相当,说明该菌株具有优良的双乙酰生产能力,能改善酸奶的香气品质。展开更多
A Lactobacillus brevis CGMCC 1306 isolated from fresh milk without pasteurization was found to have higher glutamate decarboxylase （GAD） activity. An effective isolation and purification procedure of GAD from a cell...A Lactobacillus brevis CGMCC 1306 isolated from fresh milk without pasteurization was found to have higher glutamate decarboxylase （GAD） activity. An effective isolation and purification procedure of GAD from a cell-free extract of Lactobacillus brevis was developed, and the procedure included four steps： 30%-90% saturation （NH4）2SO4 fractional precipitation, Q sepharose FF anion-exchange chromatography, sephacryl S-200 gel filtration, and resource Q anion-exchange chromatography. Using this protocol, the purified GAD was demonstrated to possess electrophoretic homogeneity via SDS-PAGE. The purification fold and activity recovery of GAD were 43.78 and 16.95%, respectively. The molecular weight of the purified GAD was estimated to be approximately 62 kDa via SDS-PAGE. The optimum pH and temperature of the purified GAD were 4.4 and 37℃, respectively. The purified GAD had a half-life of 50rain at 45℃ and the Km value of the enzyme from Lineweaver-Burk plot was found to be 8.22.5＇-pyridoxal phosphate （PLP） had little effect on the regulation of its activity.展开更多
This work describes the separation and purification of lactic acid from diluted solution by HSPE （hybrid short path evaporation） and RD （reactive distillation） as coupled process. The results showed that it is pos...This work describes the separation and purification of lactic acid from diluted solution by HSPE （hybrid short path evaporation） and RD （reactive distillation） as coupled process. The results showed that it is possible to increase lactic acid concentration up to 4.7 times higher than the raw material concentration.展开更多
文摘该研究旨在通过筛选具有较高双乙酰生产能力的乳酸菌改善酸奶香气品质。从西藏灵菇中分离筛选具有较高双乙酰生产能力的乳酸菌菌株并结合形态学特征和16S r DNA基因序列分析技术鉴定,利用气相色谱-质谱联用技术(GC-MS)对比分析筛选菌株发酵酸奶和空白酸奶香气品质差异。结果显示,菌株1-33具有较高的双乙酰生产能力,经鉴定其为植物乳杆菌(Lactobacillus plantarum)。菌株1-33制备的酸奶中双乙酰含量是空白酸奶的近4倍,乙偶姻的含量(38.92mg/L)是空白酸奶(25.46mg/L)的1.5倍左右,乙醛产量与空白发酵酸奶相当,说明该菌株具有优良的双乙酰生产能力,能改善酸奶的香气品质。
基金Supported by the National Natural Science Foundation of China (No.30570411)the Research Plan of Zhejiang Province, China.
文摘A Lactobacillus brevis CGMCC 1306 isolated from fresh milk without pasteurization was found to have higher glutamate decarboxylase （GAD） activity. An effective isolation and purification procedure of GAD from a cell-free extract of Lactobacillus brevis was developed, and the procedure included four steps： 30%-90% saturation （NH4）2SO4 fractional precipitation, Q sepharose FF anion-exchange chromatography, sephacryl S-200 gel filtration, and resource Q anion-exchange chromatography. Using this protocol, the purified GAD was demonstrated to possess electrophoretic homogeneity via SDS-PAGE. The purification fold and activity recovery of GAD were 43.78 and 16.95%, respectively. The molecular weight of the purified GAD was estimated to be approximately 62 kDa via SDS-PAGE. The optimum pH and temperature of the purified GAD were 4.4 and 37℃, respectively. The purified GAD had a half-life of 50rain at 45℃ and the Km value of the enzyme from Lineweaver-Burk plot was found to be 8.22.5＇-pyridoxal phosphate （PLP） had little effect on the regulation of its activity.
文摘This work describes the separation and purification of lactic acid from diluted solution by HSPE （hybrid short path evaporation） and RD （reactive distillation） as coupled process. The results showed that it is possible to increase lactic acid concentration up to 4.7 times higher than the raw material concentration.
