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排序方式: 共有369条查询结果,搜索用时 15 毫秒
361.
Abstract Streptococcus lactis subsp. cremoris W56 ( S. cremoris W56) is a strain partially resistant to phage attack. Derivatives which had lost either plasmid pJW563 or pJW566 no longer expressed the restriction and modification systems encoded by these plasmids. Genetic evidence for the correlation between the plasmids and the R/M systems was obtained by transformation. In addition, a third R/M system was discovered among the transformants and was shown to be encoded by pJW565. Thus, genetic evidence for at least 3 distinct R/M systems encoded by plasmids in S. cremoris W56 is presented. One of the R/M-systems showed stronger restriction of the isometric phage p2 than of the prolate phage c2. The other two systems restricted both classes of phages with equal efficiencies. 相似文献
362.
363.
Factors affecting the immunogenicity of tetanus toxin fragment C expressed in Lactococcus lactis 总被引:1,自引:0,他引:1
Pamela M. Norton Henry W.G. Brown Jeremy M. Wells Angela M. Macpherson Peter W. Wilson Richard W.F. Le Page 《FEMS immunology and medical microbiology》1996,14(2-3):167-177
Abstract The relative immunogenicity of tetanus toxin fragment C (TTFC) has been determined in three different strains of inbred mice when expressed in Lactococcus lactis as a membrane-anchored protein (strain UCP1054), as an intracellular protein (strain UCP1050), or as a secreted protein which is partly retained within the cell wall (strain UCP1052). Protection against toxin challenge (20 × LD50 ) could be obtained without the induction of anti-lactococcal antibodies. When compared in terms of the dose of expressed tetanus toxin fragment C required to elicit protection against lethal challenge the membrane-anchored form was significantly (10–20 fold) more immunogenic than the alternative forms of the protein. 相似文献
364.
The objective of this study was to develop a solution for promoting egl3 gene of Trichoderma reesei (coding β-1,4-endoglucanase, EGIII) high-efficiency secretory expression in Escherichia coli and Lactococcus lactis and to investigate the effect of the best recombinant on degrading paper and wheat straw. The coding sequence of the egl3 gene fused with a gene fragment of Usp45 (usp45) of L. lactis was cloned to pMG36e and was expressed in E. coli DH 5α (DH 5α) and L. lactis subsp. lactis MG1363 (MG1363). The maximal productivity in recombinant DH 5α was 226 mU mL−1 for extracellular EGIII and 535 mU mL−1 for intracellular EGIII. The maximal productivity in recombinant MG1363 was 1118 mU mL−1 for extracellular EGIII and 761 mU mL−1 for intracellular EGIII. The plasmid stability in recombinant MG1363 was higher than 85% at 60 generations. Recombinant MG1363 vigorously degraded paper and wheat straw and produced sufficient acids. This study provided EGIII transgenic lactic acid bacteria for processing agricultural byproducts. 相似文献
365.
Luis G. Bermúdez-Humarán Naima G. Cortes-Perez René L'Haridon & Philippe Langella 《FEMS microbiology letters》2008,280(2):144-149
IFN-γ is a cytokine produced primarily by both T lymphocytes and natural killer cells and it is considered to be an attractive therapeutic molecule. In the present study, a DNA sequence encoding the mature murine IFN-γ (muIFN-γ) protein was cloned and expressed in the food-grade lactic acid bacterium Lactococcus lactis . The activity of recombinant muIFN-γ produced by genetically engineered L. lactis was confirmed in an antiviral assay using MoV cells infected with Vesicular Stomatitis Virus. The data provide the first demonstration that a Gram-positive bacterium, L. lactis , is able to produce functional muIFN-γ. This recombinant strain could lead to the development of a new, well-tolerated vector to deliver active muIFN-γ at the mucosal level. 相似文献
366.
Dysregulation of immune responses to environmental antigens by the intestine leads to the chronic inflammatory disease, inflammatory bowel disease (IBD). Recent studies have thus sought to identify a dietary component that can inhibit lipopolysaccharide (LPS)-induced nuclear factor-kappa beta (NF-κB) signaling to ameliorate IBD. This study assessed if the lactic acid bacteria (LAB) from kimchi, suppresses the expression of tumor necrosis factor-alpha (TNF-α) in peritoneal macrophages induced by LPS. Leuconostoc lactis EJ-1, an isolate from LAB, reduced the expression of interleukin-6 (IL-6) and IL-1β in peritoneal macrophages induced by LPS. The study further tested whether EJ-1 alleviates colitis induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS) in mice. TNBS significantly increased myeloperoxidase (MPO) expression, macroscopic colitis scores, and colon shortening. Oral administration of L. lactis EJ-1 resulted in an inhibited in TNBS-induced loss in body weight, colon shortening, MPO activity, and NF-κB and inducible nitric oxide synthase expression; it also led to a marked reduction in cyclooxygenase-2 expression. L. lactis EJ-1 also inhibited the TNBS-induced expression of TNF-α, IL-1β, and IL-6; however, it induced the expression of IL-10. The M2 macrophage markers arginase I, IL-10, and CD206 were elevated by EJ-1. Collectively, these results suggest that EJ-1 inhibits the NF-κB signaling and polarizes M1- to M2-macrophage transition, which help in ameliorating colitis. 相似文献
367.
368.
K.V. Venkatesh 《Process Biochemistry》1997,32(8):651-655
A detailed metabolic flux analysis for lactic acid production by Streptococcus lactis has been carried out. A metabolic reaction set was constructed for the metabolism of S. lactis. Fluxes through these reactions were estimated by using accumulation rates of biomass, product and consumption rates of the substrate, which were obtained through experiments. The changes in the flux movement are shown for different pHs and initial lactate concentrations of the medium. The analysis indicated that pH only affected the uptake rates of lactose, whereas lactate ion concentration influenced the movement of flux through the network. 相似文献
369.
Specific mgi mutations in the α, β or γ subunits of the mitochondrial F1-ATPase have previously been found to suppress ρ0 lethality in the petite-negative yeast Kluyveromyces lactis. To determine whether the suppressive activity of the altered F1 is dependent on the F0 sector of ATP synthase, we isolated and disrupted the genes KlATP4, 5 and 7, the three nuclear genes encoding subunits b, OSCP and d. Strains disrupted for any one, or all three of these genes are
respiration deficient and have reduced viability. However a strain devoid of the three nuclear genes is still unable to lose
mitochondrial DNA, whereas a mgi mutant with the three genes inactivated remains petite-positive. In the latter case, ρ0 mutants can be isolated, upon treatment with ethidium bromide, that lack six major F0 subunits, namely the nucleus-encoded subunits b, OSCP and d, and the mitochondrially encoded Atp6, 8 and 9p. Production of
ρ0 mutants indicates that an F1-complex carrying a mgi mutation can assemble in the absence of F0 subunits and that suppression of ρ0 lethality is an intrinsic property of the altered F1 particle.
Received: 7 April 1998 / Accepted: 10 June 1998 相似文献