Progress in biotransformation of bio-based lactic acid / 生物工程学报

Fermentative production of lactic acid, an important bio-based chemicals, has made considerable progress. In addition to the food industry and production of polylactic acid, lactic acid also can be used as an important platform chemical for the production of acrylic acid, pyruvic acid, 1,2-propanediol, and lactic acid esters. This article summarizes the recent progress in biocatalytic production of lactic acid derivatives by dehydration, dehydrogenation, reduction, and esterification. Trends in the biotransformation of lactic acid are also discussed.

Immune effect of FbaAmAb2 against the surface protein FbaA of group A Straptococcus / 中华微生物学和免疫学杂志

Objective To detect the immune effect of FbaAmAb2 against the surface protein of group A Straptococcus (GAS),and explore the pathogenesis and therapy of GAS infections.Methods By subclonal and bacterial ELISA,the positive hybridoma cells were screened that can produce better titers of FbaAmAb2 against GAS-surface FbaA protein,and were injected into the peritoneal cavities of BALB/c mice to produce ascites.The collected ascites were performed to dilute,as follows,original ascite,1:2,1:4,1:8,and 1:16 to test tube agglutination.Based on the results,we selected appropriate dilution to passively immunize mice,and then challenged the mice with GAS,evaluating FbaAmAb2 neutralizing ability with GAS in mice by the survival rate of the immunized mice.Whether FbaAmAb2 could inhibit the binding of factor H to GAS was confirmed by the invasive inhibition assay.Results The IgG titer of bacteria solution ELISA is 1:160 and the titer of tube agglutination is 1∶8.The protect rates of FbaAmAb2 on preventing mice with GAS infections are as follows:66.67％ in original ascite and 1:2 diluted groups,and 50％ in 1:4 diluted group.Mice in each experimental group were evoked significantly protective immune responses compared with the PBS control by SPSS analysis.FbaAmAb2 can competitively inhibit factor H binding to the surface proteins FbaA of GAS,which decreased the entry of GAS into the cytoplasm of human epithelial cells through the binding of factor H.Conclusion FbaAmAb2 is promising to be used in emergent prevention or the clinical therapy for GAS infection and it is promising starting points for pharmacologic targeting and further development of new therapeutic agents for GAS.

Recent progress of the research on spore surface display / 生物工程学报

Spore surface display is one of attractive microorganism surface display systems. With the advantage of resistance attribute and specific assembly pattern, the technology of spore surface display now is attracting more and more attention. According to the current reports and main achievements of spore surface display, the structure and assembly of spores, the principle for construction and some existing spore surface display systems were elaborated in this paper. Now with the unique property of spores, the technique is not only widely used in production of vaccines but also has great applied potential in the field of biocatalysis and cell-factory.

Strategies for regulating multiple genes in microbial cell factories / 生物工程学报

Microbial metabolic engineering and synthetic biology are important disciplines of microbial technology nowadays. Microbial cells are fast growing, easy to be cultivated in large scale, clear in genetic background and convenient in genetic modification. They play an important role in many domains. Microbial cell factory means an artificial microbial metabolic system that can be used in chemical production. The construction of a microbial cell factory needs transferring of multiple genes or a whole metabolic pathway, which may cause some problems such as metabolism imbalance and accumulation of mesostates. This review focuses on the regulation strategies of different levels involving simultaneous engagement of multiple genes. Future perspectives on the development of this domain were also discussed.

Identification of protective truncated domain of Fba anchored on the surface of group A streptococcus / 中华传染病杂志

Objective The truncated fibronectin-binding proteins A (Fba protein) were cloned and expressed, then animals were immunized with Fba protein and subsequently challenged with group A streptococcus (GAS) to further investigate protective antibodies induced by each domain and determine the most immunogenic domain. Methods Fba proteins, which were divided into four overlaps based on the structural domains, were truncated and expressed. The fba truncated genes were amplified by polymerase chain reaction (PCR) with SSI-9 of GAS as template, and cloned into prokaryotic expression plasmid pGEX-2T and expressed in E. coli BL-21. The products were confirmed by Western blot and purified by affinity chromatography column. Female BALB/c mice were immunized with the four truncated proteins respectively, with phosphate buffered solution (PBS) as control. The serum IgG of mice was detected by enzyme-linked immunosorbent assay (ELISA). After the third immunization, mice were challenged with fatal dose of GAS (M+ Fba+ ) to evaluate the protective rates in each group. The data were compared by analysis of variance and Fisher's exact test.Results Prokaryotic expression plasmids of pGEX-2T/FbaAl, pGEX-2T/FbaA2, pGEX-2T/FbaA3 and pGEX-2T/FbaA4 were successfully constructed and the four truncated proteins were expressed and purified successfully. Serum levels of IgG in each experimental group gradually increased with immunization with Fba protein more times. After the third immunization, the IgG titer against FbaA2 1290.2, P<0. 01). After GAS challenge, four out of eight mice were protected in FbaA2 protein group, while two out of eight mice in FbaAl protein, FbaA3 protein and FbaA4 protein groups,respectively (P<0. 05). Conclusions Four truncated Fba proteins are constructed and expressed successfully. Truncated FbaA2 protein could be able to induce strongest protective immune response.

Determination of predominance amino acids specific for McAb2 to Fba protein of GAS / 中国免疫学杂志

Objective:To identify monoclonal antibody McAb2 recognizing epitope of Fba of GAS.Methods:The overlapped peptides were synthesized and their abilities to bind McAb2 were detected by dot-ELISA.The predominance amino acids specific for McAb2 were screened using phage 7 peptide library.Results:The result by dot-ELISA analysis demonstrated that the synthetized peptide,amino-acid residues 100-112~(th),could bind McAb2 with high affinity.The predominance amino acids specific for McAb2 were ITPDL,which was located in 100-110~(th)aa of Fba by panning with phage 7 peptide library.Conclusion:The domain and the predominance amino acids of Fba recognized by McAb2 is determined.The results would contribute to the research of the role of Fba on the pathogenic mechanism of GAS,the identification of function of McAb2,and the development of epitope-peptide vaccine.

Prokaryotic expression and immunogenicity of Fba,a novel fibronectin-binding protein of group A streptococus / 中华传染病杂志

Objective To express the novel fibronectin-binding protein Fba of group A streptococcus(GAS)and analyze its immunogenicity,so that to evaluate the immune responses to GAS infection.Methods fba gene was amplified by polymerase chain reaction(PCR)and confirmed by sequencing.Then it was cloned into pGEX4T-2 vector and Fba protein was expressed in E.coli BL21.The protein expression was identified by enzyme-linked immunosorbent assay(ELISA)and Westernblot.The sera from mice infected with GAS and anti-streptolysin-O positive patients were detected using microtiter plates coated with purified Fba protein as antigen.Afterward Balb/C mice were immunized with this purified protein and the sera were collected after the third immunization for the detection of IgG titer.Results It was confirmed by ELISA and Western blot that the recombinant Fba protein had a specific affinity with anti-Fba sera of rabbit.The anti-serum IgG titer of mice imrnunized with Fba protein was up to 1:4800.Conclusions GAS infection or Fba protein immunization are able to induce high serum titer of anti-Fba which could react specifically with the recombinant Fba protein.It indicates that Fba protein has good immunogenicity and antigenicity.So Fba protein could be a GAS candidate vaccine and an important tool to detect anti-GAS titer in GAS infected patients.

Construction of eukaryotic expression plasmid encoding Fba protein of group A streptococcus and elicitation of immune responses by it / 中国免疫学杂志

Objective:To construct eukaryotic expression plasmid ecording a novel surface protein Fba of GAS, and to explore its impact on host immune responses.Methods:Fba gene was amplified by PCR using strain SSI-9 (GAS M1 serotype isolates) as the template, then cloned into pcDNA3.1 for constructing eukaryotic expression plasmid pcDNA3.1/fba and sequenced. Female CD1 mice were randomly individed into 6 groups, and immunized respectively with Fba protein, M protein, pcDNA3.1/fba + Fba protein, pcDNA3.1/fba, pcDNA3.1 and PBS as control. Blood was obtained from the mice and specific antibody of IgG was detected by ELISA. Spleen cells were assessed with lymphocyte proliferation assays.CD4+T cell and CD8+T cell were detected by flow cytometry (FCM). Assay results were analyzed with SPSS10.0.Results:The IgG against Fba protein kept hightest levels in group immunized with Fba protein. The levels of lymphocyte proliferation, CD4+, CD8+T cell were significantly high in the group pcDNA3.1/fba. Conclusion:(1) Just as M protein, the antibody to Fba protein could be efficiently induced by immunization with Fba protein, which showed that Fba protein was hopefully to be a candidate protein for vaccine against GAS.(2) Eukaryotic expression plasmid pcDNA3.1/fba was successfully constructed and this recombinant plasmid could efficiently induce antibody and CD4+ T cell for againsting GAS.

Comparison among the immune effects of DNA-or protein-FimH of UPEC type 1 pilus / 中国免疫学杂志

Objective:To observe cellular,humoral and mucosal immune responses induced by DNA-or protein-based of FimH of UPEC type 1.Methods:After mice were immunized respectively with recombinant plasmid pcDNA3.1/fimH or pcDNA3.1/fimC,and the combinant FimH and FimC protein,the anti-FimH protein IgG of sera and SIgA in bladders were detected by ELISA.The lymphocyte phenotypes of CD3,CD4 and CD8 were analyzed by FCM.Results:The titers of IgG in sera and SIgA in the bladders were all low in the group immunized by recombinant FimH plamid,but the percentage of CD4+T cells in spleen was high,which revealed that recombinant FimH plamid was able to trigger better cellular immune response.The titers of IgG were very high in the group immunized by FimH protein,which suggested that the FimH protein was able to trigger better humoral immune response,but SIgA in the bladders was not detectable.Conclusion:The DNA for FimH can induce humoral,mucosal and cellular immune response.FimH protein can only induce humoral immune response.FimC protein is able to enhance the immunogenicity of FimH protein.