[Objective]To compare the effectiveness of Lactobacillus buchneri（LB）,alone or in combination with Lactobacilllus plantarum（LP）at ensiling on the fermentation,aerobic stability and nutritive value of whipgrass（He...[Objective]To compare the effectiveness of Lactobacillus buchneri（LB）,alone or in combination with Lactobacilllus plantarum（LP）at ensiling on the fermentation,aerobic stability and nutritive value of whipgrass（Hemarthria compressa（L.f.）R.Br.）silage in 1.5-l mili-silos and 50-l plastic containers.[Method]Treatments comprised control（no additives）,LP,LB and LP ＋ LB.After 90 d of storage,overall,inoculation increased the concentration of acetic and 1,2-propanediol,but it reduced the concentrations of lactic acid,water suluble carbohydrates and enthanol.[Result]The whipgrass silages treated with LB had higher acetic acid contents than the control or LP treated silages,and were free of mold,whereas the top layers of the control or LP-treated silages were moldly.In an aerobic stability test the LB-treated silages were stable,whereas those treated with LP deteriorated.In the whipgrass silages the effects of LB made less CO 2 production and stable pH.[Conclusion]It is concluded that LB has a potential as a whipgrass silage additive that protects the silage upon aerobic exposure.展开更多
L-arabinose isomerase (L-AI) is the key enzyme for D-galactose isomerization of D-tagatose by biological method. In this research, Lactobacillus plantarum WU14 with high D-tagatose yield was identified as Lactobacillu...L-arabinose isomerase (L-AI) is the key enzyme for D-galactose isomerization of D-tagatose by biological method. In this research, Lactobacillus plantarum WU14 with high D-tagatose yield was identified as Lactobacillus plantarum was isolated from the number of lactic acid bacteria from pickled vegetables. The crude L-arabinose isomerase activity of Lactobacillus plantarum WU14 with high D-tagatose yield was 13.95 U/mL under the optimal temperature 60°C, pH 7.17 and substrate concentration 0.8 mol/L, and the conversion rate of 56.12% could be gained after 28 hours. Protein structure and specific of L-Arabinose Isomerase of Lactobacillus plantarum WU14 were researched. The results showed that L-arabinose isomerase is mainly composed of alpha helix and random coil. Then the recombinant L-AI gene was inserted into the food-grade expression vector pRNA48 and expressed in L. lactis NZ9000 successfully. The target protein expression reached the maximum amount when the induced concentration of nisin reaches 30 ng/mL after 12 h. And the crude enzyme activity of recombinant bacteria reached 6.21 U/mL under 60°C. Otherwise the optimal conversion rate recombinant of L. lactis NZ9000/pRNA48-L-AI can reach 39.21% under the temperature of 50°C, pH 7.17 and D-galactose concentration was 0.6 mol/L.展开更多
This study focused on defining the differences in L. plantarum gene expression levels in different media and in different growth phases using an easy and cost-efficient monitoring of gene expression. A macroarray base...This study focused on defining the differences in L. plantarum gene expression levels in different media and in different growth phases using an easy and cost-efficient monitoring of gene expression. A macroarray based on a group of selected L. plantarum genes, 178 genes belonging to 18 main groups, printed onto a nitrocellulose filter was designed in this work. Using the macrofilters designed, the expression of a selected set of L. plantarum genes was assayed in synthetic MRS medium and in extracted carrot juice. To compare the potential differences of starter gene expression in hygienic and contaminated cultivation media, the L. plantarum strain was cultivated in both sterile and contaminated (yeast and Escherichia coli) MRS and carrot juice. The number of genes found to be regulated as a function of growth was clearly higher in MRS-based growth medium than in carrot juice, In carrot juice, expression of the gene encoding malolactic enzyme (MLE), which makes L. plantarum an advantageous microbe in e.g. wine making, was found to be upregulated in logarithmic phase of growth. The current study demonstrated that macroarrays printed on nitrocellulose filters with simple robotic systems can be analyzed by standard laboratory equipment and methods usually available in molecular laboratories. Using this technology, rapid and cost-efficient analysis of genome function of L. plantarum can be carried out e.g. in developing regions, where lactic acid fermentation of food and feed matrices is a common practice.展开更多
基金Supported by the National Science and TechnologySupport Program of the Twelfth Five-Year Plan (2011BADITB03)
文摘[Objective]To compare the effectiveness of Lactobacillus buchneri（LB）,alone or in combination with Lactobacilllus plantarum（LP）at ensiling on the fermentation,aerobic stability and nutritive value of whipgrass（Hemarthria compressa（L.f.）R.Br.）silage in 1.5-l mili-silos and 50-l plastic containers.[Method]Treatments comprised control（no additives）,LP,LB and LP ＋ LB.After 90 d of storage,overall,inoculation increased the concentration of acetic and 1,2-propanediol,but it reduced the concentrations of lactic acid,water suluble carbohydrates and enthanol.[Result]The whipgrass silages treated with LB had higher acetic acid contents than the control or LP treated silages,and were free of mold,whereas the top layers of the control or LP-treated silages were moldly.In an aerobic stability test the LB-treated silages were stable,whereas those treated with LP deteriorated.In the whipgrass silages the effects of LB made less CO 2 production and stable pH.[Conclusion]It is concluded that LB has a potential as a whipgrass silage additive that protects the silage upon aerobic exposure.
文摘L-arabinose isomerase (L-AI) is the key enzyme for D-galactose isomerization of D-tagatose by biological method. In this research, Lactobacillus plantarum WU14 with high D-tagatose yield was identified as Lactobacillus plantarum was isolated from the number of lactic acid bacteria from pickled vegetables. The crude L-arabinose isomerase activity of Lactobacillus plantarum WU14 with high D-tagatose yield was 13.95 U/mL under the optimal temperature 60°C, pH 7.17 and substrate concentration 0.8 mol/L, and the conversion rate of 56.12% could be gained after 28 hours. Protein structure and specific of L-Arabinose Isomerase of Lactobacillus plantarum WU14 were researched. The results showed that L-arabinose isomerase is mainly composed of alpha helix and random coil. Then the recombinant L-AI gene was inserted into the food-grade expression vector pRNA48 and expressed in L. lactis NZ9000 successfully. The target protein expression reached the maximum amount when the induced concentration of nisin reaches 30 ng/mL after 12 h. And the crude enzyme activity of recombinant bacteria reached 6.21 U/mL under 60°C. Otherwise the optimal conversion rate recombinant of L. lactis NZ9000/pRNA48-L-AI can reach 39.21% under the temperature of 50°C, pH 7.17 and D-galactose concentration was 0.6 mol/L.
基金Tekes,the Finnish Funding Agency for Technology and Innovation,is gratefully acknowledged for the financial support of this work.
文摘This study focused on defining the differences in L. plantarum gene expression levels in different media and in different growth phases using an easy and cost-efficient monitoring of gene expression. A macroarray based on a group of selected L. plantarum genes, 178 genes belonging to 18 main groups, printed onto a nitrocellulose filter was designed in this work. Using the macrofilters designed, the expression of a selected set of L. plantarum genes was assayed in synthetic MRS medium and in extracted carrot juice. To compare the potential differences of starter gene expression in hygienic and contaminated cultivation media, the L. plantarum strain was cultivated in both sterile and contaminated (yeast and Escherichia coli) MRS and carrot juice. The number of genes found to be regulated as a function of growth was clearly higher in MRS-based growth medium than in carrot juice, In carrot juice, expression of the gene encoding malolactic enzyme (MLE), which makes L. plantarum an advantageous microbe in e.g. wine making, was found to be upregulated in logarithmic phase of growth. The current study demonstrated that macroarrays printed on nitrocellulose filters with simple robotic systems can be analyzed by standard laboratory equipment and methods usually available in molecular laboratories. Using this technology, rapid and cost-efficient analysis of genome function of L. plantarum can be carried out e.g. in developing regions, where lactic acid fermentation of food and feed matrices is a common practice.
