Abstract:Abstract:Being a surface structure of bacteria，flagella have been thought to simply act as the locomotive organelles for a long time．In recent years，as increasing information gathered from studies on the pathogenicity of flagella，we found flagella could contribute to invasion and adhesion to the host cells，playing an important role in the biofilm formation and being correlated with bacterial virulence secretion system． Binding of flagellin and toll-like receptor 5 may stimulate signaling pathway，resulting in the pro-inflammatory response．Meanwhile，flagella act as a new immune adjuvant as well，because of their good immunity character．This article summarizes the current knowledge of bacterial flagella，including their structure，contribution to the pathogenicity of the bacteria，and their potential application in immunity．

Abstract:Abstract:β-Barrel outer membrane proteins are the major components of the outer membrane of Gram-negative bacteria，which are in contact with the extracellular environment directly．β-barrel outer membrane proteins play key roles in nutrients absorption and keeping membrane integrity．They are also involved in the pathogenicity and multiple-antibiotic resistance of pathogenic bacteria． Therefore，β-barrel outer membrane proteins are very important for the survive of bacteria cells，and full understanding of the biosynthesis，folding and membrane insertion of these proteins is of great significance for fighting against pathogenic bacteria and utilization of beneficial bacteria． In this article，the research progress on the biosynthesis in cytoplasm，the translocation across the inner membrane，transportation to periplasm and the folding and membrane insertion of β-barrel outer membrane proteins are reviewed，and the progress on the study of OMPs assembly machinery is emphasized．

Abstract:Abstract:Bacteria predominantly adapt to environmental changes to ensure their growth and proliferation through onecomponent，two-component and three-component regulatory systems． Conjugative pilus expression (Cpx) system is one of the two-component regulatory systems in gram-negative bacteria．It is composed of the membrane-anchored sensor kinase CpxA，the cytosolic responding regulator CpxR and the accessory protein CpxP in the periplasm． In this review，the components of the Cpx system and their structural characteristics were introduced and the latest research on Cpx signal integration was summarized．Further attempts to better understand the mechanisms were also proposed．

Abstract:Abstract:［Objective］To study the population composition and antimicrobial activities of endophytes in medicinal plant Toddalia asiatica．［Methods］Endophytes were isolated from T．asiatica by using an exterior sterilization method，in combination with adding antimicrobial agents．Endophytes were classified and identified by morphological and molecular characters．Antimicrobial activities of endophytes were measured by using paper disc diffusion method．［Results］Three strains of endophytic bacteria，one strain of endophytic actinomyces and 82 strains of endophytic fungi were isolated from T．asiatica． Fusarium，Pestalotiopsis，and Aspergillus were the dominant populations in T． asiatica．Antimicrobial activities of these endophytes were measured against 30 pathogenic microbes，and 18 strains possess substantial inhibitory activities，of which 16 strains were endophytic fungi belonging to 11 genera．［Conclusion］ Endophytic strains with antimicrobial activities were obtained to explore the application of endophytic resources from T．asiatica．

Abstract:Abstract:［Objective］To investigate the function of glpX gene in mycobacterial physiology and metabolism.［Methods］The glpX mutant of Mycobacterium smegmatis was constructed byusing mycobacteriophage Che9c-encoded recombination system．Then the growth difference between mutant and wild type strain was compared on various carbon sources．Furthermore，we analyzed the glpX gene transcriptional level of wild type strain growing on glucose or oleic acid by realtime PCR．［Results］The growth of M．smegmatis on glycerol or oleic acid is strongly attenuated after the deletion of the glpX gene．The transcription of glpX gene is upregulated in the medium with oleic acid as the sole carbon source． ［Conclusion］ These results indicate that the fructose 1，6-bisphosphatase encoded by glpX gene is required and nonredundant for mycobacterial gluconeogenesis.

Abstract:Abstract:［Objective］To screen efficient nitrogen fixation endophytes from rice and to analyze their growth-promoting properties．［Method］We isolated strains from the roots of rice in the field where it has a rice-rice-green manure rotation system for 30 years．Efficient strains were screened by acetylene reduction assay． Phylogenetic analysis is based on 16S rRNA gene，nifH gene and the composition of fatty acid． In addition，we also detected the ability of indole acetic acid secretion through the Salkowski colorimetric method，measured the production of siderophore through the blue plate assay and detected phosphate solubilization，to analyze the growth-promoting properties．［Result］ A total of 48 strains were isolated，in which DX35 has the highest nitrogenase activity．It belongs to Herbaspirillum seropedicae after identification．Its nitrogenase activity (181.21 nmol C2H4/(mg protein·h)) was 10 times as much as the reference strain Azotobacter chroococcum ACCC10006．In addition，it also can secrete siderophore and solubilize phosphorus．［Conclusion］Strain DX35，belonging to Herbaspirillum seropedicae，is an efficient nitrogen fixation endophytes．

Abstract:Abstract:［Objective］The aim of the study is to propose a dynamic acetic acid resistance mechanism through analysis on response of cellular morphology，physiology and metabolism of A．pasteurianus CICIM B7003 during vinegar fermentation．［Methods］Vinegar fermentation was carried out in a Frings 9 L acetator by strain B7003 and cultures were sampled at different cellular growth phases．Simultaneously，percentage of capsular polysaccharide versus dry cells weight，ratio of unsaturated fatty acids to saturated fatty acids，transcription of acetic acid resistance genes，activity of alcohol respiratory chain enzymes and ATPase were detected for these samples to assay the responses of bacterial morphology，physiology and metabolism．［Results］ When acetic acid was existed，no obvious capsular polysaccharide was secreted by cells．As vinegar fermentation proceeding，percentage of capsular polysaccharide versus dry cells weight was reduced from 2.5% to 0.89%．Ratio of unsaturated fatty acids to saturated fatty acids was increased obviously which can improve membrane fluidity．Also transcription level of acetic acid resistance genes was promoted． Interestingly，activity of alcohol respiratory chain and ATPase was not inhibited but promoted obviously with acetic acid accumulation which could provide enough energy for acetic acid resistance mechanism．［Conclusion］On the basis of the results obtained from the experiment，A．pasteurianus CICIM B7003 relies mainly on the cooperation of changes of extracellular capsular polysaccharide and membrane fatty acids，activation of acid resistance genes transcription，enhancement of activity of alcohol respiratory chain and rapid energy production to tolerate acidic environment．

Abstract:Abstract:The effect of transgenic cotton on the rhizosphere bacteria can be important to the risk assessment for the genetically modified crops.［Objective］ We studied the rhizosphere microbial community with cultivating genetically modified cotton．［Methods］The effects of transgenic Bt + CpTI Cotton (SGK321) and its receptor cotton (SY321) on rhizosphere total bacteria and ammonia oxidizing bacteria population size were studied by using droplet digital PCR．We collected rhizosphere soil before cotton planting and along with the cotton growth stage (squaring stage，flowering stage，belling stage and boll opening stage)．［Results］There was no significant change on the total bacterial population between the transgenic cotton and the receptor cotton along with the growth stage．However，the abundance of ammonia oxidizing bacteria (AOB) in both type of cottons showed significant difference between different growth stages，and the variation tendency was different．In squaring stage，the numbers of AOB in rhizosphere of SY321 and SGK321 increased 4 and 2 times，respectively． In flowering stage，AOB number in rhizosphere of SY321 significantly decreased to be 5.96×105 copies/g dry soil，however，that of SGK321 increased to be 1.25×106 copies/g dry soil．In belling stage，AOB number of SY321 greatly increased to be 1.49×106 copies/g dry soil，but no significant change was observed for AOB number of SGK321．In boll opening stage，both AOB number of SY321 and SGK321 clearly decreased and they were significantly different from each other．Compared to the non-genetically modified cotton，the change in abundance of ammonia oxidizing bacteria was slightly smooth in the transgenic cotton，［Conclusions］Not only the cotton growth stage but also the cotton type caused this difference． The transgenic cotton can slow down the speed of ammonia transformation through impacting the number of AOB，which is advantageous for plant growth．

Abstract:Abstract:［Objective］To evaluate the effect of long-term fertilization on soil microbial community and soil chemical and physical properties． ［Methods］Using a high-throughput pyrosequencing technique，we studied microbial community in the 0－300 cm soil samples covering a 20-year field-experiment with different fertilization applications including inorganic fertilizer alone (N 300 kg/ hm2，P2O5 150 kg/hm2 and K2O 60 kg/hm2) and inorganic fertilizer combined with straw (same application rate of N and P fertilizer combined with 5. 4 t straw)．［Results］Actinobacteria and α-proteobacteria were the predominant groups in the topsoil (0－20cm)．As the soil depth increased，the relative abundance of actinobacteria decreased whereas that of proteobacteria，especially γ-proteobacteria and β-proteobacteria increased and gradually became the dominant groups in the subsoil (20－300 cm)．Long-term fertilizing applications significantly affected soil microbial communities throughout the soil profile，and increased the relative abundance of ammonia-oxidizing archaea at 0－40 cm depth．In addition，agriculture management，e． g．irrigation may be an important driving factor for the distribution of ammonia-oxidizing bacteria in soil profile． Total nitrogen and organic carbon contents were the most influential factors on microbial community in the topsoil and in the subsoil，respectively．［Conclusion］ Long-term fertilizer applications altered soil nutrient availability within the soil profile，which was likely to result in the different microbial community structure between the fertilizer treatments，especially for the subsoil．

Abstract:Abstract:［Objective］Ag85B (Rv1886c) is secreted during the early stages of infection by Mycobacterium tuberculosis．The purpose of this study was probed into the immune response against Ag85B in vivo．［Methods］Ag85B was prokaryotic expressed and identified，its immunological characteristics were evaluated with indirect-ELSIA，Sandwich-ELISA and enzyme-linked immunospot assay (ELISPOT)．［Results］ Ag85B was mainly expressed in form of inclusion body confirmed by SDS-PAGE． Western blot analysis shows that the fusion protein had good specific reaction with serum of tuberculosis patient and serum of mice immunized with LM-Ag85B．C57BL/6 mice were subcutaneously immunized with Ag85B，the production of IFN-γ and IL-4 in the spleen cells was determined by Sandwich ELISA，the level of IFN-γ was significantly higher than that of IL-4(P＜0.001) in the Ag85B immunization group，it indicated the protein induced Th1-tendency immune responses．Furthermore，purified protein derivative (PPD) used as coating antigen，antibody titer against Ag85B in murine serum reached 1:6400，it was demonstrated that Ag85B could also induce humoral immune responses． Additionally，C57BL /6 mice were intravenously immunized with M．tb H37Rv and bacillus Calmette-Guérin (BCG) respectively for 42 days，M．tb H37Rv group intended to induce Ag85B specific Th1 type immune response，and its ability of eliciting cellular immunity was significantly stronger than BCG group(P＜0.001)．［Conclusion］Ag85B can affectively induce strongly Th1-tendency immune response and humoral response．Whereas，BCG prime vaccination only can elicit low levels of Ag85B240－259 specific immune response．The study laid foundation for probing the pathogenic mechanism，the development of novel vaccine and the establishment of clinical diagnostic method．

Abstract:Abstract:［Objective］To compare the effect between two segments (PBS and GBS) of ClassⅡ-associated invariant chain peptide (CLIP) of invariant chain (Ii) on humoral immune by immune carrier．［Methods］First six hybrids containing Newcastle disease virus (NDV) epitope F2 and Ii segments (Cyt/TM/F2，Cyt/TM/F2/GBS，Cyt/TM/PBS/F2，Cyt/TM/F2/TRIM，Cyt/TM/F2/GBS/TRIM，Cyt/TM/PBS/F2/TRIM ) were reconstructed respectively．Then they were inserted into the prokaryotic expression vector pET-32a and transformed into E.coli Rosetta (DE3) to induce the expression of the recombinant proteins．Finally mice were immunized with these purified fusion proteins，the specific antibody titers were detected with ELISA，to compare and analyze the effect among different groups on the immune response．［Results］All the six groups immunized with these hybrids increased antibody titers (from 1.5-fold to 4.9-fold，respectively) compared with the group immunized with F2 alone．Within the above six groups，the hybrids containing either PBS or GBS had higher antibody titers from 1. 6-fold to 2.4-fold than the hybrids without the both segments．However，the group of the hybrid containing PBS had a 1.5-fold antibody titer higher than the group of GBS hybrid． ［Conclusion］ Ii cytosolic and transmembrane domains could increase the immune response，while the segment PBS behaved better than GBS in an immune vector based on Ii．

Abstract:Abstract:［Objective］The aim of this study was to screen bacteria that can produce antithrombotic．［Methods］ We screened the target bacteria on VY/4 plate and casein plate from more than 20 samples such as water，soil，rabbit manure，sheep manure and deadwood．We detected the antithrombotic activity by fibrin plate and fibrin tube．We identified the target bacteria by morphological characteristics，physical and chemical properties and 16S DNA sequence homology.［Results］We obtained 5 strains that can produce antithrombotic．We found that the extracellular protein of strain LDS33 shows both stronger fibrinolytic activity and stronger anticoagulation activity．According to the morphology，physiochemical properties，16S DNA sequencing and phylogenetic tree，strain LDS33 is identified as Bacillus pumilus．［Conclusion］Bacillus pumilus LDS33 can produce highly active anticoagulation and thrombolysis double active protein.

Abstract:Abstract:［Objective］ To study the immunogenicity of co-expression of p30，one of a group specific antigens，and glycoprotein gp90 genes of Reticuloendotheliosis virus (REV)．［Methods］p30 and gp90 genes were amplified with the template of plasmid pPB101 containing the whole sequence of spleen necrosis virus(SNV)，and cloned into pET-28a(+) vector．The positive clone pET-p30-gp90 was identified by enzyme analysis and sequencing．The co-expressed protein p30-gp90 was confirmed by SDS-PAGE and Western blot analysis． After quantitation，the purified protein p30-gp90 was immunized to Balb/c mice three times to prepare the p30-gp90 specific anti-serum．Afterwards，we detected the REV infected Chick Embryo Fibroblasts (CEF) by Immunofluorescence assay (IFA) with the prepared anti-serum．［Results］The p30-gp90 was co-expressed efficiently by SDS-PAGE and Western blot analysis．The anti-serum of p30-gp90 reacts with REV infected CEF in IFA．［Conclusion］The expressed protein of p30-gp90 keeps good immunogenicity．