Preparation of immobilized Lactobacillus plantarum agent for silage / 生物工程学报

Lactic acid bacteria and cellulose degrading bacteria play an important role in fermentation process of silage, because they can prevent the rancidity and increase the nutritive value of silage. But the propagation of lactic acid bacteria will inhibit the activity of cellulose degrading bacteria in the silage fermentation system. This problem can be solved by releasing lactic acid bacteria and cellulose degrading bacteria in different time. Therefore, we immobilized lactic acid bacteria as a microbial agent for sustained release. Firstly, the optimal balling concentration of the composite immobilized carrier and composite immobilized carrier were obtained by immobilization of blank balls and corncob adsorbed Lactobacillus plantarum S1 respectively. The best immobilization condition of L. plantarum S1 was obtained by comparing the immobilized rate and balling effect of two kinds of balls, which were embedded by sodium alginate (SA), CMC-Na and embedded-crosslinked by SA, CMC-Na, polyvinyl alcohol (PVA). The results showed that the best balling concentration was achieved by using 6% PVA+0.4% SA+0.3% CMC-Na for embedding-crosslinking and 1.2% SA+0.5% CMC-Na for direct embedding respectively. In addition, comparing with the mechanical strength and embedding rate of five kinds of immobilization process, the best immobilized process was obtained by adding of the mixture of immobilized carriers (1.2%SA+ 0.5%CMC-Na) and corncob adsorbed L. plantarum S1 slowly into 4% CaCl₂ for 24 hours. The corncob adsorption and SA embedding methodology can effectively increase the embedding efficiency of Lactobacillus plantarum S1.

Rab5a promotes LPS-induced cytokine expression in macrophages / 中国免疫学杂志

Objective:To establish cell lines stably expressing Rab5a and its the inactive mutant Rab5aN133I,analyze the effect of Rab5a on the expression of cytokines in LPS-stimulated RAW264.7 cells .Methods:RAW264.7 cells were transfected with Rab5a and its inactive mutant vector Rab5a N133I separately,and then screened by G418.Rab5a stable expressing cell lines were identified by Real time-PCR.The growth of the stable cell lines was analyzed by MTT assay.After the stable cell lines were stimulated by LPS for different time periods,the expression of iNOS,TNF-αand IL-6 was detected.Results:Rab5a and Rab5aN133I transfection resulted in elevated Rab5a mRNA expression compared with the control cells ( P<0.05 ).Rab5a overexpression enhanced the proliferation of RAW264.7 cells.However,the proliferation of Rab5aN133I cells was significantly slower than the control cells ( P<0.05).Overexpression of Rab5a promoted LPS-induced production of iNOS,TNF-αand IL-6 in RAW264.7 cells (P<0.01). Conversely,overexpression of Rab5aN133I abolished the stimulating effects of Rab5a.Conclusion: Rab5a promoted LPS-induced expression of iNOS,TNF-αand IL-6 in RAW264.7 macrophages in a GTP-binding ability-dependent manner.