Abstract:Abstract:The Nocardioides genus was established by Prauser H．in 1976 according to morphological and physiological characteristics，as well as partial chemotaxonomic analyses of 17 nocardio-form actinobacteria isolated from soil，based on which a novel species Nocardioides albus was proposed as the type species． With the development in the technologies of isolation，purification and taxonomy，more and more members of this genus with varied morphological，physiological and biochemical characteristics were increasingly discovered from different sources，while all of them shared the same diagnostic characteristics of the genus． In the past 50 years，some of the members of the genus Nocardioides were ever transferred in or out and then some species description was ever emended． Till date，there were 56 validly described species in this genus． Some members of this genus were used in agriculture and industry． The objective of this review is to summarize the research advances in the genus Nocardioides，such as the changes of the taxonomic position and emendation description of the species as well as the application prospect in industry and agriculture．

Abstract:Abstract:Animal-originated enterotoxigenic Escherichia coli (ETEC) are major pathogens resulting in newborn and young animal diarrhea． Adhesins and enterotoxins，both are essential for the pathogenicity of ETEC，are two major virulent factors of ETEC． Adhesion of animal-originated ETEC fimbrial adhesins (mainly including K88，K99，987P，F18，F17 and F41) to intestinal epithelial cells is the initial and most important step involved in the ETEC infection． From the 1960s，studies on ETEC fimbrial genes，structure，biosynthesis，regulation of expression，interaction between fimbriae and host receptors have helped to better understand the biology and role of these organelles in pathogenesis． These studies also provide insight into new diagnostic tools and development of vaccines and inhibitors of ETEC colonization．

Abstract:Abstract: ［Objective］ We determined the phylogenetic position of a heterotrophic nitrifying-aerobic denitrifying bacterium X3， and detected its nitrogen removal characteristics for providing evidence to explain the principle of heterotrophic nitrification-aerobic denitrification and to improve the process in purification of marine-culture wastewater．［Methods］ The evolutionary position of the strain was determined based on its morphological，physiological，biochemical characteristics and 16SrRNA gene sequence． The nitrification-denitrification ability of this strain was detected by detecting its nitrogen removal efficiency and growth on different inorganic nitrogen source． ［Results］ Strain X3 was identified as Halomonas sp． It grew optimally at salinity 3%，pH 8.5，C:N 10:1 at 28℃，and it could still survive at 15% salinity． The removal of NH +4-N，NO－2-N and NO－3-N was 98. 29%，99.07%，96.48% respectively within 24 h． When three inorganic nitrogen existed simultaneously，it always utilized ammonia firstly，and the total inorganic nitrogen removal was higher than with only one nitrogen，suggesting that strain X3 has the ability of simultaneous nitrification and denitrification and completing the whole nitrogen removing process．［Conclusion］Strain X3 belonged to the genus of Halomonas． It had strong simultaneous nitrification and denitrification capability and could live in high-salinity environment．

Abstract:Abstract:［Objective］ To screen and identify a bacterium capable of converting daidzein to S-equol．［Methods］We used antibiotics to limit unrelated bacterial growth and enrich the target bacteria，and isolated the aim bacterial strain from rat intestine． The metabolite of daidzein was tested by HPLC，MS and NMR． The taxonomic group of the strain was identified by 16S rDNA sequence analysis and phylogenetic tree; the strain's morphological and physiological biochemical characters were also tested．［Results］ A gram-negative facultative bacterial strain LH-52 (JN861767) capable of transforming daidzein to S-equol was isolated． Basic Local Alignment Search Tool (BLAST) search of LH-52's 16S rDNA sequence on GenBank suggested that this strain has 99% similarity to that of Proteus mirabilis，the morphological and physiological biochemical characteristics of LH-52 also showed highly similarity to P． mirabilis． Based on these data，we identified LH-52 as P． mirabilis，and named it as P． mirabilis LH-52． The results of HPLC，MS and NMR suggested that the metabolite of daidzien was S-equol．［Conclusions］ Bacteria strain P． mirabilis LH-52 was the first reported facultative bacteria strain capable of converting daidzein to S-equol，and might be more suitable in industrial application than obligate anareobic bacterial strains．

Abstract:Abstract:［Objective］ To investigate functions of flgKpcc gene in Pectobacterium carotovorum subsp． carotovorum (P.c.c)．［Methods］The gene knock-out mutant ΔflgKpcc and complemented strain ΔflgKpcc-KH were generated by biparental mating and their phenotypes including cell morphology，motility，pathogenic factors，and pathogenicity were investigated．［Results］ Non-flagellum，cell precipitation in the culture and significantly attenuated motility on 0.3% semisolid medium were observed in ΔflgKpcc compared to Pectobacterium carotovorum subsp． carotovorum S1． In addition，significant decrease in cellulase and protease activity，biofilm formation，and pathogenicity on host plant were found in ΔflgKpcc．While there were no apparent difference in growth rate in vitro，ΔflgKpcc-KH，the complementation strain，restored the phenotype of ΔflgKpcc to the wild type level． ［Conclusion］ The gen of flgKpcc not only influences the cell motility，but also pathogenic factors to lead to the decreased pathogenicity in Pectobacterium carotovorum subsp． Carotovorum．

Abstract:Abstract:［Objective］ Pseudomonas fluorescens 2P24 is an effective biocontrol agent for soil-borne plant diseases caused by microbial pathogens． The PcoI/PcoR quorum-sensing system，which influences the colonization ability of 2P24 on wheat rhizosphere，is an important factor for disease suppression． In this study we performed random mutagenesis to screen novel regulators of the pcoI gene，a biosynthase gene responsible for N-acyl-homoserine lactone (AHL) production．［Methods］ A gacA gene mutant carrying a pcoI-lacZ fusion was employed as the reporter strain and subjected to a random mini-Tn5 insertion mutagenesis． Expression of pcoI kept at a low level under the gacA－negative background． The Tn5-mutants with increased pcoI transcription were selected．［Results］ Two mutants with significantly increased pcoI expression were identified from～10000 Tn5-inserted colonies． The interrupted locus in the mutants was identified as the mvaT gene，a global regulator belonging to the H-NS family． A homolog of the mvaT gene，named mvaV，was also found in the genome draft sequence of 2P24． Genetic inactivation of mvaT or mvaV gene resulted in increased transcription of pcoI and the production of AHL molecules． Further qutitification by HPLC showed that the 2，4-diacetylphloroglucinol (2，4-DAPG) levels in culture supernatant of the mvaT and mvaV mutants were significantly lower than that of the wild type strain． Furthermore，the mvaT or mvaV mutation drastically improved biofilm formation in 2P24．［Conclusion］MvaT and MvaV may function as an important regulatory complex controlling biocontrol capacity of P． fluorescens 2P24.

Abstract:Abstract:［Objective］ To study the effects of overexpression of key enzyme genes (prs，purF and guaB) on guanosine production in Bacillus amyloliquefaciens TA208.［Methods］ The prs，purF，guaB and prs-purF genes were inserted into constructed expression plasmid PBE43． All these constructed plasmids were electroporated into B. amyloliquefaciens TA208． The transcriptional level of various genes in the resulting strains was tested by real-time quantitative PCR． The activity of inosine 5'-monophosphate dehydrogenase in the resulting strains was detected． Finally，cell growth，glucose consumption and guanosine production of 4 engineering strains along with control strain were examined． ［Results］ The transcriptional analysis showed that overexpression of prs，purF and guaB gene accompanied by their own transcription level up-regulated． Overexpression of prs or purF genes alone slightly down-regulated the transcriptional level of purine operon，but overexpression of guaB gene independently did not disturb the transcription of prs gene and purine operon． Enzyme activity analysis showed that overexpression of prs or purF gene did not change the activity of inosine 5'- monophosphate dehydrogenase and its activity increased by 126% through overexpression of guaB gene． Finally，by fermentation flask test， we found that overexpression of prs and purF gene alone could not promote guanosine accumulation． However，overexpression of guaB gene resulted in an increase in the production of guanosine，which was 20. 7% higher than the control strain． The guanosine concentration and the conversion ratio from glucose to guanosine in the host strain containing co-expression plasmid were 14. 4% and 6. 8% higher than the control strain． ［Conclusion］Overexpression of guaB gene could enhance the guanosine yield in the culture broth． However，for prs and purF gene，only co-expression of them could lead to a significant improvement of guanosine production in B．amyloliquefaciens．It should provide a valuable insight into the construction of industrially important strains for guanosine production by metabolic engineering．

Abstract:Abstract: ［Objective］ To clone the xylitol dehydrogenase gene from Gluconobacter oxydans CGMCC 1.637，to characterize enigmatic properties of xylitol dehydrogenase and to investigate the induction abilities of various carbon sources on the oxidative activity of xylitol dehydrogenase and the effect of various carbon sources on the bioconversion of d-xylulose to xylitol in G.oxydans CGMCC 1.637.［Methods］Touch-down polymerase chain reaction (PCR) was applied to clone the xylitol dehydrogenase gene from chromosomal DNA of G.oxydans CGMCC 1.637.［Results］ The 798-bp open reading frame of xylitol dehydrogenase encoded a protein of 265 amino acids，with the molecular mass of 27. 95 kDa.Sequence analysis of the putative protein revealed it to be a member of short-chain dehydrogenase/reductase family．Xylitol dehydrogenase showed oxidative activity with xylitol and sorbitol and no activity with other polyols，such as darabitol．Km and Vmax with xylitol was 78.97 mmol/L and 40.17 U/mg，respectively．The highest oxidative activity of xylitol dehydrogenase for xylitol was only 23.27 U/mg under optimum conditions (pH 10.0，35℃)．However，the activity of its reverse reaction，d-xylulose reduction，reached 255. 55 U/mg under optimum conditions (pH 6.0，30℃)，10-times higher than that of xylitol oxidation． Oxidative activity of xylitol dehydrogenase was induced when G. oxydans CGMCC 1.637was cultivated on d-sorbitol. D-arabitol，which supported a high cell growth，inhibited the oxidative activity of xylitol dehydrogenase and the bioconversion ability of G.oxydans CGMCC 1.637.［Conclusions］ The obtained gene from G.oxydans CGMCC 1.637 was a novel gene encoding xylitol dehydrogenase． Oxidative activity of xylitol dehydrogenase in G. oxydans CGMCC 1. 637 and the bioconversion ability of G. oxydans CGMCC 1.637 after grown on darabitol were inhibited，which provided a valuable clue for further study to increase xylitol yield from d-arabitol.

Abstract:Abstract:［Objective］ We compared bacterial and archaeal diversity and community structure of mangrove soil under different vegetation，and to reveal better understanding of microbial resources． ［Methods］ Bacterial and archaeal 16S rRNA gene libraries were constructed and analyzed for soils under Kandelia candel trees，Sonneratia apetala trees，and naked tideland，in Dongzhaigang Mangrove National Nature Reserve of Hainan Island． Template DNA was directly extracted from soil samples． PCR were amplified using primers 27F /1492R (bacterial) and Arch21F/Arch958R (archaeal)．［Results］A total of 16 phyla dominated by Proteobacteria and Chloroflexi were detected in bacterial libraries，and 6 groups of Crenarchaeota and 7 groups of Euryarchaeota，predominated by Marine Benthic Group C and Marine Benthic Group D，respectively were found in archaeal libraries． Shannon-Wiener index (H') and Schao1 estimator indicated that soil microbial diversity under the introduced species Sonneratia apetala was much lower than indigenous species Kandelia candel，even lower than naked tidal flat sediment near mangrove． Distinct differences in microbial community structure under different vegetation were observed． Soil microbial community structure under Kandelia candel was much similar with that of naked tideland.［Conclusion］ Mangrove soil contained rich population of bacteria and archaea; there existed distinct differences in mangrove soil microbial community structure and diversity among different vegetation．

Abstract:Abstract:［Objective］Two-chamber microbial fuel cells (MFCs) were set up to understand the electrogenic capacity of MFCs fed with lactic acid to investigate the distribution characteristics of microflora in the anode biofilm，supernatant，and sediment.［Methods］ Using lactic acid as a carbon source in the anode，we explored the MFCs start-up process and the efficiency of electricity production，and also investigated the spatial distribution of microbial communities using scanning electron microscope (SEM) and PCR-denaturing gradient gel electrophoresis (DGGE) techniques.［Results］The results indicate that the MFCs reached the highest voltage，0.56 V on the seventh day after startup． When external resistance and current density was 80 Ω and 415 mA/m2，respectively，the power density reached its maximum at 82 mW/m2.SEM revealed that a massive bacillus was attached tightly to the surface of the positive electrode． DGGE profiles revealed that microorganisms on the anode's surface were most similar to that of inoculated sludge， consistent with the major microorganism groups in anode suspension and sludge substrate． Communities developed on the anodes included exoelectrogenic bacteria，i.e. Comamonas testosterone，and Arcobacter butzleri.［Conclusion］This research demonstrates that MFCs fed with lactic acid can generate a high efficiency of current density，and that the dominant microbes on the anodes are similar to that of inoculated sludge．

Abstract:Abstract:［Objective］We developed subunit vaccines against H5 or H9 subtype avian influenza viruses (AIV) and infectious bursal disease viruses (IBDV) ．Viral protein 2 (VP2) of IBDV was used as cargo protein to display a 12-amino-acid (aa) immunodominant epitope derived from N-terminal M2 extracelluar domain (nM2e) of H5 or H9 subtype AIV．［Methods］The aa and nucleotide sequence of nM2e was determined by comparing the available avian influenza vaccine strains and alignment the AIV sequence available in GenBank． One copy of H5 or H9 nM2e was inserted into PBC region of VP2 origin from IBDV B87 vaccine strain by fusion polymerase chain reaction． The VP2BC nM2e recombinants were cloned into Bac-to-Bac expression system and transfected to Sf9 cell． The expressed chimeric protein was characterized by indirect immunofluorescence assay and Western blotting，and subsequently was used as antigen to develop vaccine． The non-immunized chicken was given two injections with the vaccine at a 4-week interval． Serum against VP2 and nM2e was tested by indirect ELISA and virus neutralization in chick embryo fibroblast． ［Results］ Both VP2BC nM2e recombinants were successfully constructed and expressed in Sf9 cell． Both chimeric proteins elicited antibody against VP2 and nM2e． The antibody level elicited by VP2BC nM2eH5 vaccine was higher than that of VP2BC nM2eH9．［Conclusion］Both chimeric proteins were immunigenic，and the efficacy of VP2BC nM2eH5 was higher than VP2BC nM2eH9 in chicken．

Abstract:Abstract:［Objective］Photopigments，including carotenoid and bacteriochlorophyll a，are the most important functional units of photosynthesis in purple bacteria． We developed rapid qualitative and quantitative methods to determine photopigments．［Methods］ Using Rhodopesudomonas palustris CQV97 as a reference，we used image gray intensity analysis，absorption spectrophotometry，thin layer chromatography (TLC)，HPLC and mass spectrometry (MS) for photopigment analysis．［Results］ The total amount of photopigments increased by 13.5% by using modified acetonemethanol extraction． We developed two types of photopigment fingerprintings by TLC and HPLC，estimated the apparent relative content of each photopigment of fingerprintings，and determined the corresponding relationships between Rf value of each photopigment on TLC fingerprinting and retention time of each photopigment elution in HPLC fingerprinting． Based on the data from the absorption spectra，MS and related photopigment biosynthetic pathway analysis，we identified 11 photopigments in CQV97 strain． Using this strain as a standard，we analyzed photopigments of the tested samples by TLC or HPLC． It was shown that (1) the relative standard deviation (RSD) of the two methods was less than 5%; (2) the compositions and contents of the theory sample were consistent with that of the standard sample; (3) the photopigment compositions of the real sample was the same as the standard sample，but the photopigment content was different． ［Conclusion］ Both of TLC and HPLC analyses for photopigment determination have good stability and repeatability． The fingerprintings analyses are suitable for rapid determination of photopigments of purple bacteria and have important application in control of regulation mechanism for photopigment synthesis．

Abstract:Abstract:［Objective］We surveyed the composition and diversity of uncultured archaea in Xinjiang Dunbasitawu salt Lake sediment．［Methods］ Environmental total DNA was directly extracted from the sediment．We constructed clone library of 16S rRNA gene amplified with archaea-specific primers． A total of 59 positive clones were randomly selected from the library and identified by restriction length polymorphism (RFLP) with enzyme Hae Ⅲ． Clones with the unique RFLP pattern were sequenced，and then by phylogenetic analysis．［Results］ The clone coverage C value was 89%，and Shannon-Wiener index was 2. 69. In total，21 Operational Taxonomic Units (OTUs) were obtained and affiliated with Euryarchaeota (92%) and Crenarchaeota (8%)．The most of clones were affiliated to Halobacterium (24%)，Haloarcula (18%)，Natronorubrum (14%)，and Halorubrum (8%)，which belonged to family Halobacteriaceae (88%) with high similarity to that from thalassohaline environment．In addition，11% of clones had less than 97% similarity with archaea sequences deposited in GenBank database．［Conclusion］Compared with other similar Hypersaline environments，archaea diversity in Dunbasitawu salt lake was a little lower．The proportion of archara was different，but the composition is consistent． It was implied that some potential new species or lineages maybe exist in Dunbasitawu salt lake.

Abstract:Abstract:［Objective］To isolate and identify a versatile carbohydrate-degrading bacterium from marine environments，and characterize the extracellular agarase activity.［Methods］The I2 staining method was applied in the isolation of agarosedegrading bacteria from coastal sediments of the Jiaozhou bay nearby Qingdao city，China． The JZB09 strain was cultured in multiple media using various complex polysaccharides as the sole carbon source to test the carbohydrate utilizing abilities． The 16S rRNA gene was cloned，sequenced and analyzed to identify the taxonomic position of the strain． Crude extracellular proteins were prepared using (NH4) 2 SO4 precepitation method． The dialyzed enzyme extract was applied in further studies including activity testing，activity staining，and agarose degrading for oligosaccharides purifiction． Three purified oligosaccharides were individually analyzed using thin layer chromatograph (TLC) and MALDI-TOF MS method．［Results］ The agarolytic marine bacterium，Persicobacter sp． JZB09，could use multiple complex polysaccharides as the sole carbon source and grew well on agarose，cellulose and xylan． The extracellular enzyme extract exhibits efficient and extensive degradation activity on agarose with an activity of 77.2 U/mg proteins． The extracellular agarase system (EAS) in the crude extracellular enzymes contains at least two agarose depolymerases with molecular masses of approximately 45 kDa and 70 kDa，respectively． A series of degradation products from agarose by the EAS was purified and identified as neoagaro-oligosaccharides，among which neoagarotetraose was the major product of the crude enzymatic products，which suggests that β-agarase is the major constituent of the JZB09 EAS．［Conclusion］The polysaccharide-degrading bacterium Persicobacter sp．JZB09 and its polysaccharide-degrading system is promising for the exploration of polysaccharide depolymerase resources including β-agarases．

Abstract:Abstract:［Objective］We studied the algicidal mechanism of extracellular substances of algicidal bacteria strain BS03 (Microbulbifer sp.) on photosynthetic characteristics，antioxident enzyme system and cysteine-dependent aspartate specific protease-3 (Caspase-3) of Alexandrium tamarense． ［Methods］ We tested photosynthetic pigments，chlorophyll fluorescence efficiency，antioxidant systems and caspase-3 activity in the algae cells treated with 0.5%，1.0%，1.5% and 2.0% BS03 cell-free filtrate after 12，24，36 and 48 h.［Results ］(1) The chlorophyll-a and chlorophyll fluorescence efficiency Fv/Fm decreased with the increase of BS03 cell-free filtrate and treatment time． Carotenoids contents of A． tamarense cells treated with low BS03 (0.5% and 1.0%) cell-free filtrate were higher than the control．(2) Antioxident enzyme activities varied as treatment time and concentration． Malodialdehyde (MDA) contents increased significantly with BS03 cell-free filtrate treatment．(3) Caspase-3 protease activities of algal cells increased by BS03 cellfree filtrate.[Conclusion] BS03 inhibited the photosynthesis whereas enhanced the lipid peroxidation of the cellular membrane of Alexandrium tamarense，indicating its algicidal activity．

Abstract:Abstract:［Objective］ To characterize the class Ⅰ integron in Acinetobacter baumannii and to analyze the correlation between integron and drug resistance． ［Methods］ In total 187 strains were collected between 2008 and 2009. All strains were tested by Kirb-Bauer disk diffusion test for drug resistance． PCR and DNA sequencing were used to detected classⅠintegrase gene and to clarify the context of gene cassette．［Results］ Class Ⅰ integrase gene was detected in 100 (53.4%) of the isolates analyzed． Seven different gene cassettes were identified，including a new integron (GenBank: HQ322622) carrying an unknown protein probably associated with recombination． The vast majority of the cassettes encoded amonoglycoside resistance gene，including aacA4，aadA1，aacC1，aac6Ⅱ，aadA2. Susceptibility data show that strains carrying classⅠintegron were significantly more resistant to all of the antibiotics tested than isolates lacking classⅠ integron． The correlation between the presence of integron and the multidrug-resistance of A． baumannii was statistically significant.［Conclusion］Drug resistance genes integrated by Class Ⅰ integron were widespread in A． baumannii． Class Ⅰ integron plays an important role in resistance of A． baumannii．