Abstract:Abstract: Clostridium thermocellum (C.thermocellum ) is the dominant microorganism that can efficiently degrade lignocellulose． Extensive studies were done for secreting the cell surface-bound protein complex known as the cellulosome．C.thermocellum is regulated by carbon sources，reflected in overall multiple cellulase production and in the cellulosomal subunit profile．To produce a cellulosomal protein complex is a dynamic assembly process．In recent years，it becomes a hotspot to study how C．thermocellum senses the insoluble substrate，regulates the secretion of relevant enzymes，and assembles the supramolecular-degradation enzyme complex．This review summarized the research advance in genomics，transcriptomics，proteomics and extracellular carbohydrate-sensing mechanism in C．thermocellum，and analyzed the mechanism and dynamic process of C．thermocellum in lignocellulose degradation．

Abstract:Abstract:The process of denitrifying anaerobic methane oxidation (DAMO)，which uses methane as electron donor for denitrification，can achieve nitrogen remove of wastewater and simultaneously reduce the emission of methane．The research of DAMO mechanism focuses on two pathways -the reverse methanogenesis coupled denitrification and the nitritedependent anaerobic methane oxidation (n-damo)．Considering that DAMO process makes a significant contribution to global carbon and nitrogen cycling，our review summarizes the progresses of DAMO in recent years and focuses on the enrichment culture of microorganism，especially the microbiological characteristic of enrichment containing M．oxyfera．The microbiological mechanisms and parameters of the process are also reviewed． On this basis，some practical problems and prospects in the engineering application of the process are also discussed．

Abstract:Abstract:［Object］ The phylogenetic relationship of 90 species of the genus Bacillus was analyzed using fatty acid biomarkers．［Methods］Fatty acid biomarkers were detected by Microorganism Identification System (Sherlock MIS) with gas chromatography (Agilent 7890 N，MIDI Inc., Newark，DE)．Based on the distribution characteristics of fatty acid，10 parameters e. g. 16:0 iso，16:0，17:0 iso，17:0 anteiso，15:0 iso，15:0 anteiso，15:0 iso/15:0 anteiso，17:0 iso/17:0 anteiso，diversity index (H) and evenness index (J) were constructed to perform fatty acid phylogeny of the genus Bacillus.［Results］In the 90 Bacillus species 29 fatty acid biomarkers were found with the carbon lengths ranging from 10 to 20． From statistical analysis，sum of relative percentage content of the 6 largest fatty acid biomarkers were 15:0 anteiso，15:0 iso，17:0 anteiso，16:0，17:0 iso and 16:0 iso． Among them，15:0 anteiso and 15:0 iso possessed high content with fully distribution in all species tested． Of the biomarkers，17:0 anteiso，16:0，17:0 iso and 16:0 iso had middle content，being not fully distributed，and the rest belonged to low content and not fully distributed． Ninety Bacillus species were divided into five fatty acid groups，e.g．stenothermic group，eurithermophile group，alkaliphilic group，acidophilus group and mesophilic group． The cluster analyses of phenetic classification and fatty acid classification were further compared to find that both classification systems yielded an identical result．［Conclusion］ Phylogenetic classification system of the genus Bacillus using fatty acid biomarkers embraces Bacillus phylogeny with physiological and biochemical charateristics．This fatty acid-based phylogenetic system may become a new system for classification．

Abstract:Abstract:［Objective］Xanthomonas campestris pv．campestris (Xcc) is the cause agent of black rot of crucifers．Xcc uses type III secretion system(T3SS) to deliver T3SS effectors(T3SEs) directly into host cells，where they play important roles in pathogenesis． Many identified T3SEs genes contain plant-inducible promoter(PIP) box and － 10 box in their promoter regions． However，the relation among PIP-box，－ 10 box and － 10 region，－ 35 region of the classic promoter is unclear，and the conservative characteristic of － 10 box sequence is hardly reported． The aim of this study was to analyze the putative promoter region of T3SE gene avrACXcc8004．［Methods］ Through 5' RACE，the transcriptional start site of avrACXcc8004 was identified．Fusion PCR was introduced to generate the site-mutagenesis of － 10 box for constructing the GUS fusion report strains．［Results］The 5' RACE results indicate that the transcription start site was A．After analysis，we found that － 35 region was located 8 bp downstream of PIP-box，and － 10 box was exactly overlapped with － 10 region．The whole motif of PIP-box，－ 35 region，and － 10 box was then counted as: TTCAC-N15 -TTCGC-N8 -TTGATGN18 -TACGTT． The GUS assay results demonstrate that the site-mutagenesis of － 10 box caused a higher expression of avrACXcc8004．The GUS activities in the mutant strains ΔhrpX and ΔhrpG were significantly lower than that in the wild type Xcc strains．［Conclusion］PIP-box is tandem with － 35 region，－ 10 box is just the same as － 10 region，－ 10 box is important for the transcription of avrACXcc8004，and HrpG and HrpX activate the expression of avrACXcc8004，despite of － 10 box site-mutagenesis.

Abstract:Abstract:［Objective］The aim of the study was to investigate the influences of high-fat diet and methanogens inhibitor (bromochloromethane，BCM) on the gut microbiota and fat metabolism in mice.［Methods］Thirty two female C57BL/6J mice were randomly divided into 4 groups: fed respectively by Low-fat diet，Low-fat diet + BCM，High-fat diet and Highfat diet + BCM． BCM was administrated through drinking water for six weeks． The body weight of mice was recorded every week．At the end of experiment，the blood was collected for serum biochemical analysis． Bacterial communities in cecal digesta were analyzed by denaturing gradient gel electrophoresis (DGGE) and real-time PCR． VFA (volatile fatty acid) concentrations in feces were determined by gas chromatography． Expressions of fat-related genes in liver were analyzed using real-time PCR．［Results］DGGE analysis shows that samples from mice fed with high-fat diet gathered together，and separated with samples from low-fat diet group． However，both the fat level in diet and BCM treatment had no effect on the numbers of total bacteria，sulfate reducing bacteria and methanogens．The acetate proportion in feces was significantly decreased (P＜0.05) when fed high-fat diet to mice (P＜0.05)．BCM treatment significantly increased the propionate proportion (P＜0.05)．High-fat diet also significantly increased the levels of high-density lipoprotein cholesterol (HDL-C)，low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TG) in blood (P＜0.05)．High-fat diet up-regulated the expression of TGH gene (P＜0.05)．［Conclusion］High-fat diet affected cecal microbiota and fat metabolism of mice，whereas BCM treatment had little effect．

Abstract:Abstract:［Object］ To study the resistance mechanisms to quinolones in Aeromonas hydrohila isolated from aquatic animals.［Methods］The drug-resistant spectrum of 23 strains was determined．Quinolone-resistance determining regions of gyrA and parC genes in both screened and in-vitro induction drug-resistant strains were analyzed．Then the detection of quinolone drugs relative efflux pump genes qepA，oqxA and mdfA was performed．The qnrA，qnrB，qnrC，qnrD and qnrS genes were also analyzed at the same time.［Results］All organisms were resistant to more than 5 drugs; 39.1% (9/23) of the isolates were quinolone resistant，of which 55.6% (5/9) were enrofloxacin resistant. All the enrofloxacin-resistant isolates harbored qnrS gene，but none of the enrofloxacin-resistant strains harbored qnrA，qnrB，qnrC，qnrD genes and the efflux pump genes of qepA，oqxA and mdfA．AH19 possessed the gyrA and parC genes double mutation，plasmidmediated quinolone resistance gene qnrS and efflux pump，3 drug resistance mechanisms simultaneously，while the two drug-resistant mechanisms of AH4，AH7 and AH20 were gyrA and parC genes double mutation and qnrS gene．GyrA gene mutation and qnrS gene occurred in AH6．Compared to the strain ATCC7966，the in-vitro induction drug-resistant strain ATCC7966-QR had both the gyrA and parC genes mutation．［Conclusion］The mechanisms of resistance to quinolones in the A．hydrophila isolates of this study mainly depended on the existence of plasmid-mediated gene qnrS and the variation of the target site of quinolone drugs，whereas，the drug resistance mechanism relying on the efflux pump system only existed in individual strains.

Abstract:Abstract:［Objective］ In order to analyze the biodiversity of cultivable facultative-alkaliphilic actinobacteria and the enzymes they produced．［Methods］Total 10 soil samples were collected from saline-alkaline environments of Fukang，Xinjiang province． Facultative-alkaliphilic actinobacteria strains were isolated and identified by 16S rRNA gene sequence analysis．Enzymes including amylase，proteinase，xylanase，and cellulase were detected．［Results］ Total 116 facultative-alkaliphilic actinobacterial strains and 4 alkali-tolerant actinobacterial strains were isolated from the samples，and those strains were distributed within 22 genera in 13 families and 8 orders of actinobacteria based on their 16S rRNA gene sequence analysis．The ratio of non-predominant Streptomyces and Nocardiopsis strains were 53.3%．The positive rates of amylase，proteinase，xylanase and cellulase were 35.8，37.6，28.3 and 17.5%，respectively．［Conclusion］Diverse facultative-alkaliphilic actinobacteria were discovered from saline-alkaline environments of Fukang． Facultativealkaliphilic actinobacteria are a potential source for enzymes．The study would facilitate the knowledge of the diversity of facultative-alkaliphilic actinobacteria，and provide the technical basis for exploration of facultative-alkaliphilic actinobacteria resources.

Abstract:Abstract:［Objective］To reveal the diversity of bacterioplankton during winter and spring in Zuohai lake，Fuzhou City，China．［Methods］We constructed 16S rRNA gene clone libraries in the two seasons (January，2012 and April，2012);the Shannon diversity index，Simpson dominance index and Evenness index of the bacterial community in the two samples were compared，and the analysis for the bacterial community structures of this two water samples was conducted．［Results］The Shannon diversity index in January achieved 3. 53，and the Evenness index achieved 0.66; While the Shannon diversity index of April reached 3.37，and the Evenness index reached 0.64．It indicated that the bacterial communities in the two water samples were diverse，but the Evenness indexes were very low． Bacterial belonging to 5 phyla were identified: α-proteobacteria，β-proteobacteria，bacteroidetes，actinobacteria and cyanobacteria．Also，there were many sequences belonging to unidentified bacteria．In January， bacterial community with β-proteobacteria predominated followed by cyanobacteria; while cyanobacteria was the predominant bacterial communities in April.［Conclusion］The distribution of the bacteria in the two seasons has differences，especially the most dominant bacteria differed significantly．In addition，bacterial diversity in the two water samples was high，and compared with in spring，that in winter has higher bacterial diversity，but exit a large number of unidentified bacteria in this environment.

Abstract:Abstract:［Objective］To clarify an important biological characteristic of virus infecting cyanobacteria (A-4L) and to isolate，identify new bloom-forming cyanobacteria viruses，we studied A-4L concentric rings plaque formation in Anabaena sp．PCC7120.［Methods］One step growth curve was designed to estimate the latent period and burst size of A-4L. The initial titer of A-4L was about 2.8×1010 PFU/mL. The appropriate titer suspension of A-4L was inoculated onto the lawns of Anabaena sp．PCC 7120 which have been cultivated at different time．Pathological change of lawns was observed and recorded daily．To investigate the effect of lighting on the concentric rings plaque formation，plates were cultivated and infected under continuous lighting (L:D=24 h:0 h)，periodic lighting (L:D=14 h:10 h) or 3 days continuous lighting after periodic lighting for 3 days．The ultra-morphology of purified A-4L was observed by negative staining electron microscopy．［Results］The latent period of A-4(L) was 0.5 h － 2 h and the burst size was about 247 infectious units per cell. Under periodic lighting，concentric rings plaques were observed in the plate after infection 3 days to 4 days and the distance between two rings was about 3 mm．Statistic analysis showed that there was a correlation between the number of concentric rings in plaques and infection days，which was“n－1”．Compared with the periodic lighting，the plaques without concentric rings were observed under continuous lighting． However，the concentric rings formed under periodic lighting disappeared gradually after turning to continuous lighting，which demonstrated that the formation of concentric rings plaques depended on the periodic lighting．Negative staining electron microscopy showed that the A-4L particle had a spheroidal head with diameter about 50 nm and a tail with length about 10 nm which was similar to the characteristic morphology of cyanobacterial podoviruses．［Conclusion］ A-4L is a virus infecting cyanobacteria which can form concentric rings plaque． And periodic lighting is the key conditions for the concentric rings plaque formation of A-4L.

Abstract:Abstract:［Objective］We developed a recombinant pseudorabies virus (PRV) vaccine against porcine circovirus type 2 (PCV2).［Methods］PCV2 ORF2 gene was inserted into vector pG to produce the recombinant PRV vector pGO; the genome of PRV attenuated vaccine and the transfer plasmid pGO were transfected by using LipofectamineTM 2000 Reagent into swine testis cells for homologous recombination to obtain the recombinant PRV． Six-week-old female Kunming mice were immunized two intramuscular immunizations 4 weeks apart，and then challenged with the virulent PCV2 NY strain at 8 weeks after the first immunization．［Results］A recombinant PRV expressing PCV2 ORF2 was successfully constructed，and named PGO． There was a low ELISA antibody level of PCV2-specific humoral immune response elicited by recombinant virus PGO for the first immunization but high significantly for the second immunization．PCV2 antigen-specific T-cell proliferative responses can be elicited by immunization with recombinant virus． Challenge experiments show that the recombinant virus and PCV2 inactivated vaccine could both protect the mice against PCV2 challenge，suggesting that the recombinant virus can be an excellent potential vaccine．［Conclusion］The results show the recombinant PRV expressing PCV2 ORF2 had good immunogenicity.

Abstract:Abstract:［Objective］In this study，we developed a strategy for accurate，rapid and simultaneous quantification of six carotenoids by substitute reference standard.［Methods］We prepared six carotenoid standards of spirilloxanthin series from Rhodopesudomonnas palustris CQV97 by spectrophotometry，thin layer chromatography and HPLC．The simultaneous quantification method for six carotenoids was established by HPLC using tartrazine and lycopene as substitute reference standards.［Results］We established the HPLC fingerprinting of carotenoids of spirilloxanthin series．The quantitative calibration function relationships between two substitute reference standards and six carotenoids were explored．Based on the quantitative calibration function relationships，we quantitatively analyzed carotenoid contents of two samples of CQV97 and YL28 strains．The RSD and recovery of carotenoid contents determined by substitute reference standards method were consistent with quantitative analysis of carotenoid standards method．［Conclusion］ The substitute reference standards were capable of accurately transmitting the quantitative relationship of tested samples． The method could realize the simultaneous quantification of six carotenoids.

Abstract:Abstract:［Objective］The aim of this study is to identify strain JX-09 and confirmed that the strain is the pathogen of diseased grass carp (Ctenopharyngodon idellus).［Methods］A pathogenic strain JX-09 was isolated from the diseased grass carp. The strain was identified based on physiological and biochemical characteristics，and the sequence analysis of 16S rRNA．Virulence of strain JX-09 to healthy grass carp was also tested．Furthermore，drug sensitivity was detected with Kirby-Bauer’s agar diffusion method．［Results］ Strain JX-09 was identified as Plesiomonas shigelloides by biochemical analysis and molecular biology．The P．shigelloides strain was re-isolated from the artificial infected grass carp，and the LD50 was about 6.4×104 cfu/g．Drug sensitive tests showed that strain JX-09 was susceptible to aztreonam，cefazolin，cephalothin and ceftriaxone，and resistant to kanamycin， medicamycin，vancomycin and piperacillin．［Conclusion］Strain JX-09 was the pathogen of grass carp with muscle erosive disease．To the best of our knowledge，this is the first report that P．shigelloides as the pathogenic strain of grass carp.

Abstract:Abstract:［Objective］We determined the present distribution of serogroups and virulence factors among F18 Escherichia coli isolates from pigs with diarrhea and/or edema disease during 1998 to 2006．Epitope of F18 fimbriae was also analyzed．［Methods］A total of 75 E.coli isolates harbored fedA gene coding the major subunit of F18 fimbriae were identified by biochemical procedures and serological techniques． PCR was used to detect the virulence-related genes．An indirect ELISA was also used to analyze the antigen patterns of 33 F18 bearing E．coli strains． ［Results］Among these 75 isolates，62 were determined to be placed in total 8 serogroups，and O107 and O139 were main serogroups (61.3%) of fedA-positive isolates．The percentage of the detection of the estI，estII，elt，stx-2e，astA，orfA，irp2，fyuA，ler and eaeA among 75 strains was 64.0%，46.7%，28.0%，62.7%，26.7%，9.3%，9.3%，9.3%，1.3% and 1.3%，respectively．of the 75 strains 19 were positive for stx-2e gene only，and 20 for estI/estII/stx-2e．The 11 MAbs against F18“a”，“b”and“c”had been used in indirect ELISA to detect F18 pili antigen，44.0% (33 /75) of these isolates were F18 + when cultured in TSB cultures．Among 33 isolates expressed F18 fimbriae，21 isolates were identified as the “ac”variant，2 were identified as the“ab”variant and 10 reacted only with F18“a”specific MAbs while not with F18“b”，“c”specific MAbs． The results also revealed that the 11 MAbs recognized at least 6 epitopes including at least three common typespecific antigenic determinants“a”and two“b”antigen determinants and one“c”antigen determinant.［Conclusion］The antigenic variants of F18 fimbriae are biologically distinct．F18ab fimbriae are expressed poorly in vitro，while F18ac are more efficiently expressed in vitro and most often are linked with enterotoxin (STa and/or STb) production and serogroups O107．Some F18 fimbrial antigens experienced some variations comparing with those of F18ab and F18ac strains.