Abstract:Spore germination of Bacillus could be triggered by germinants like L-alanine which is thought to bind to and stimulate specific receptors. The GerA receptor responds to L-alanine in Bacillus subtilis. A homologous gerA operon of B. subtilis was isolated from Bacillus thuringiensis subsp. kurstaki. RT-PCR showed that the transcription of the gerA operon was switched on 3 hours after the initiation of sporulation and this operon was cotranscribed. Disruption of the gerA operon led to blockage of the L-alanine-initiated germination pathway and showed a delayed inosine-induced germination response. The germination rate of the gerA complementary strain spore deriving from introducing gerA operon into the disruption mutant was even faster than that of the wild type strain spore. This is caused by overdose GerA receptors which could enhance the sensibility of complementary spore to L-alanine. The overdose GerA receptors came from introducing multicopy plasmid- pKSV7 (about five copies) which could increase the amount of GerA receptors. After treatment of D-cycloserine which could inactivate alanine racemase irreversibly, L-alanine-induced spore could germinate faster than untreated spore. The combination of 0.1 mmol/L D-cycloserine and 1 mmol/L L-alanine could trigger spore germination induced by L-alanine effectively.

Abstract:To elucidate the role of N-glycosylation in fetal donkey dermal cell (FDD)-attenuated equine infectious anemia virus (EIAV), we constructed an N-glycosylation reverse-mutation molecular clone, pLGN191N236N246. This viral molecular clone was derived from the infectious clone pLGFD3-8 by site-directed mutagenesis. This clone was used to transfect fetal donkey dermal (FDD) cells. Infectious characteristics of transfectants were monitored by RT-PCR, indirect immune fluorescence and reverse transcriptase activity assay. After three passages in FDD cells, viral replications in the supernatant of cell cultures were detected by all the above three methods and viral particles were clearly observed by electron microscopy. The construction of the N-glycosylation reverse-mutation infectious clone provides a solid basis for further study of the mechanism of attenuated pathogenesis and in-creased immune protection of EIAV attenuated vaccines.

Abstract:We constructed a food-grade secretion expression vector and used it for reporter protein expression in live delivery vehicle L lactisMBP71. The p32 fragment, which containing the stronger p32 promoter,,was amplified by polymerase chain reaction(PCR) with the plasmid pMG36e as template. After being purified, the p32 fragment was ligated with SPusp45 fragment amplified from genomic DNA of L lactis MG1363. The fusion fragment p32-SPusp45 was inserted into the food-grade vector pSH91 to construct a secretion expression vector, pSQ. The coding sequence of NucA (nucA) was also amplified from Staphylococcus aureus chromosome and inserted into pSQ under the control of p32 promoter to construct a recombinant plasmid pSQ-nucA. Nuclease plate activity assay and zymograme assay demonstrate that NucA was secretion expressed from L lactis harboring the recombinant plasmid pSQ- nucA, and the quantity of NucA secreted into supernamant was about ten times more than which in cell lysate. Results also indicate that expression efficiency of L lactis/pSQ-nucA was higher than that of L lactis/pSQZ-nucA, constructed by us earlier.

Abstract:The virulence of Listeria monocytogenes is directly related to its ability to spread from cell to cell without leaving the intracellular milieu. Among the bacterial factors involved in cell-to-cell spread, actin-polymerizing protein ActA is required for bacterial spread to adjacent cells, while the broad-range phospholipase C (PC-PLC) contributes to bacterial escape from secondary vacuoles. [Methods] Based on homologous recombination technology, we constructed a double gene-mutant strain by deleting two virulence factors, ActA and PC-PLC, [Objective] its toxicity and immunopotency was evaluated in murine model. [Results] And then, the mutant strain was further verified the absence of ActA and PC-PLC using Western blot analysis and phospholipase activity assay. It showed highly attenuated and its 50% lethal dose in BLAB/c mice was increased at least 103-fold compared to the parent strain. Nevertheless, mice preimmunized with the mutant strain elicited strong T-cell responses and fully protected against a lethal challenge with the virulent strain. [Con-clusion] These results not only verified that ActA and PC-PLC were essential virulence factors for L. monocytogenes, but also demonstrated that the mutant strain possessed good immunogenicity with higher safety. The mutant strain could be further studied as a vaccine candidate to prevent listeriosis and used as a vector to deliver heterologous antigens. Fur-thermore, it provided the possibilities to elucidate the molecular mechanisms of pathogenesis and immune response trig-gered by L. monocytogenes.

Abstract:Strains producing biological surfactants were isolated from formation water of Daqing oil field, Heilongjiang Province, China. From which a lipopeptide producing strain ZW-3 was screened out by PCR of the sfp gene. The mor-phology ,cultural characteristics ,physiological , biochemical properties and chemotaxonomy of strain ZW-3 were studied. The strain is rod shaped (0.7～0.8 mm×2~3 mm) , gram-positive, spore-forming and aerobic bacteria. Its (G+C) content was determined to be 42.2 mol%. Phylogenetic analysis based on 16S rRNA gene sequence demonstrated that it was closely related to the genus Bacillus subtilis, and the metabolites of strain ZW-3 was analyzed by thin layer chromatog-raphy and high performance liquid chromatography, the result indicated that the biosurfactant strain ZW-3 produced was surfactin. It could reduce surface tension of bacterial fermentation culture medium and water/oil- interfacial tension from 68.82 mN/m to 24.88 mN/m and from 23.53 mN/m to 4.57 mN/m ,respectively, and its mixture with 1.8%NaOH could reduce water/oil- interfacial tension to an ultra low level (1.2×10-3mN/m), Its critical micelle concentration (CMC) was tested to be 33.3 mg/L(3.24×10-5 mol/L)at 25℃, and it had excellent emulsifying(2.89U) and foaming property. All these results showed that this biosurfactant had great potential in pharmaceutics, environmental protection, cosmetic, oil recov-ery and many other application fields.

Abstract:The 3C protease from foot-and-mouth disease virus (FMDV 3Cpro) is critical for viral pathogenesis, has vital roles in both processing of the polyprotein precursor and RNA replication, and is a potential anti-viral drug target. In the study, 3C gene of FMDV from serotype Asia I was obtained through Polymerase Chain Reaction (PCR), and subcloned into baculovirus transfer vector pMelBac-B. The recombinant transfer plasmid and linearized baculovirus DNA were co-transfected into sf9 insect cell, and the recombinant baculovirus were screened by plaque cloning and PCR identifica-tion. After amplification of recombinant baculovirus on cell passages, the recombinant virus were seeded on sf9 cell with 10 multiplicity of infection (MOI), and cells were harvested 72 hours after infection. The expressing product of 3C gene in insect cells was detected by Sodium Dodecyl Sulphate PolyAcrylamide Gel Electrophoresis (SDS-PAGE) and Western blot. The result demonstrated that the 3C gene was successfully expressed in insect cells. The product was a 23 kDa pro-tein and could be recognized by anti-FMDV serum in western blot. The results provide a basis for research of the assembly of FMDV empty capsids in vitro and the design of antivirus drug.

Abstract:RecA/Rad51/RadA recombinases are important recombination proteins with conserved functions. Studies on the enzymes have shown that members of RecA/Rad51/RadA family from bacteria, eukaryota, methanogens and halophilic archaea have UV inducibility. However, the UV inducibility of RadA homologues from hyperthermophilic archaea is controversial.We analyzed the UV inducibility of Sulfolobus tokodaii RadA by RT-PCR and immune assays. Comparing with the mock, the transcription and expression of the radA increased 2 and 1.5 folds respectively after UV irradiation at 100 J/m2, or 3 and 1 fold at 200 J/m2. These results demonstrated that S. tokodaii RadA could be induced after UV treatment. In addition, pro-teome induction analysis proved that there existed a DNA damage induction response in S. tokodaii, which further supported RadA inductility in this hyperthermophilic archaeon.

Abstract:Diversity of bacteria and archaea was studied in deep marine sediments by PCR amplification and sequence analysis of 16S rDNA. Sample analysed was from IMAGES(International Marine Past Global Change Study) 147 at site of the south slope of the South China Sea. DNA was amplified from samples at the surface layer of core MD05-2896. Phylogenetic analysis of clone libraries showed a wide variety of uncultured bacteria and archeae. The most abundant bacterial sequences (phylotypes) corresponded to the Proteobacteria, followed by the Planctomycete, Acidobacteria and candidate division OP10. Phylotypes ascribing to Deferrobacteres, Verrucomicrobia, Spirochaetes and candidate division clades of OP3, OP11, OP8 and TM6 were also identified. Archaeal 16S rDNA sequences were within phylums of Crenarchaeota and Euryarchaeota, respectively. The majority of archaeal phylotypes were Marine Benthic Group B(MBGB), Marine Crenar-chaeotic GroupⅠ(MGⅠ), Marine Benthic Group D(MBGD) and South African Gold Mine Euryarchaeotic Group(SAGMEG). Additional sequences grouped with the C3, Methanobacteriales and Novel Euryarchaeotic Group (NEG). These results indicate that bacteria and archaea are abundant and diversified in surface environment of subseafloor sediments.

Abstract:[Objective] We developed an indirect ELISA method for detecting Bordetella bronchiseptica (Bb) pertactin antibodies based on the recombinant pertactin protein expressed in Escherichia coli (DE3) strain. [Methods and results] The prn gene encoding Bb pertactin was fused to the downstream of glutathione S-transferase (GST) of pGEX-KG expression vector, resulting in the fusion expression plasmid pGEX-prn. SDS-PAGE showed that the GST-PRN fusion protein was expressed in high level in BL21 carrying pGEX-prn. The strong reactivity of the GST-PRN fusion protein, specifically with antiserum against porcine Bordetellosis caused by Bb HH0809, was identified by Western blot. The recombinant protein fragment of rPRN was purified from the GST-PRN fusion protein digested by protease thrombin with the purity of 93.1℅. The rPRN-based indirect ELISA was developed for detecting antibodies against PRN. The ELISA could detect positive samples in experimentally infected pigs fourteen days post inoculation and the degree of sensitivity was over 4 times higher than the latex agglutination test with the coating antigen of killed Bb. Thirty-two point seven percent of positive samples were detected in 1,229 clinical samples while no false positive results were found in detecting 7 antisera against porcine bacterial diseases. Sera samples from two bordetellosis-positive pig fields were tested by the indirect ELISA method and the results indicated that pigs were infected by Bb during the nursery periods. [Conclusion] The assay showed excellent specificity, sensitivity and reduplication, and can be useful for epidemiological survey and clinical diagnosis of swine bordetellosis.

Abstract:[Objective] We evaluated the efficacy of the recombinant pertactin (PRN)-specific active or passive immunization against Bordetella bronchiseptica (Bb) in an aerosol challenge model established by using BALB/c mice. [Methods and results] Mice, immunized subcutaneously with two doses of purified glutathione S-transferase (GST)-PRN protein mixed with an equal volume of Freund’s adjuvant, produced robust PRN-specific IgG antibody activity. All 20 mice vaccinated with GST-PRN protein survived aerosol challenge with three times the 50% lethal dose (LD50) of virulent Bb HH0809 compared with 3 of 20 GST protein-treated controls and 4 of 20 PBS-treated controls that survived. Furthermore, we observed complete protection against intraperitoneal challenge with ten times the LD50 of virulent HH0809 strain in mice that were injected intraperitoneally with 0.5 ml rabbit anti-GST-PRN serum. No survivors were observed in mice that received either rabbit anti-GST serum or PBS alone. [Conclusion] The recombinant PRN protein had strong immuno-genicity against Bb infection.

Abstract:The ApxⅡA、ApxⅢA、ApxⅣA genes from Actinobacillus pleuropneumoniae serotype 3 and the ApxⅠA gene from Actinobacillus pleuropneumoniae serotype 5 were respectively cloned into the prokaryotic expression vector pGEX-5X-3.Then the recombinant expression plasmids were respectively transformed into E.coli BL 21 and fusion pro-tein expression were induced by IPTG. The expression products were purified by precipitation with ammonium sulfate and chromatography on Sephadex G-200. SDS-PAGE indicated that the productsexpressed at a high level when the recombi-nant E.coli BL21 was induced 2h, joining IPTG to final concentration 1mmol/L. Western blot analysis showed that the expression products had immunogenicity and specificity.Subunit vaccines were made by different purified expression products and Freund's adjuvant. Mice were immunized at 30 days and 45 days with the subunit vaccines. Then the mice were challenged with the APP of serotype 1, 3, 5,7or 10 at 60 days. The result of animal immunoprotection test showed that subunit vaccines (ApxⅠA +ApxⅣA, ApxⅠA + ApxⅢA +ApxⅣA ,ApxⅠA + ApxⅡA + ApxⅢA + ApxⅣA) could offer 58.4%、66.6%、91.7% protection in mice against the challenge of serotype 1, 5 and 7 APP, respectively. These results suggested that the recombinant proteins had good immunogenicity and the subunit vaccine containing four kind of re-combinant proteins could induce better immunoprotection.

Abstract:We constructed a recombinant plasmid containing the N-terminus gene of vacA gene of Helicobacter pylori and studied the effect of VacA on the secretion of macrophages as an individual virulence determinant. VacA gene amplified by Polymerase Chain Reaction (PCR) from Helicobacter pylori was cloned into eukaryotic expression vector pDsRed-Monomer-C1. The recombinant plasmids were verified by restriction endonucleases analysis and nucleotide se-quencing. Then the recombinant plasmids pDsRed-Monomer-C1/vacA were transfected into macrophages. Their expres-sion in macrophages was examined by Western blot and fluorescence microscope. Vacuolated phenotype in macrophages was observed by electron microscopy and neutral red uptake. The cytokine content of TNF-α or IL-1β in the culture me-dium was tested quantitatively with Enzyme Linked Immunosorbent Assay( ELISA) kit, respectively. The effect of pyr-rolidine dithiocarbamate (PDTC), an inhibitor of NF-kB, on the secretion of macrophages transfected with the recombi-nant plasmids, was also studied. Restriction endonucleases analysis and nucleotide sequencing showed that the eukaryotic expression recombinant pDsRed-Monomer-C1/vacA was successfully constructed. A clear vacuolated phenotype devel-oped in some of macrophages transfected with the recombinant plasmids. VacA over-expressed increased the level of TNF-a and IL-1b. PDTC decreased the production of TNF-a and IL-1b induced by VacA. In conclusion, we have suc-cessfully constructed the eukaryotic expression plasmid encoding VacA. The over-expression of VacA fusion protein can up-regulate secretion of macrophages. Activation of NF-kB is probably involved in VacA induced cytokines production.

Abstract:To investigate the potential pathogenicity of Mycoplasma penetrans (M. penetrans) and the possible molecular mechanisms, we investigated whether M. penetrans lipid-associated membrane proteins (LAMPs) could induce mouse macrophages Raw264.7 apoptosis by activating nuclear factor kB (NF-kB). Apoptosis was detected in M. penetrans LAMPs-stimulated mouse macrophages by Annexin-V-FITC staining and DNA fragmentation analysis. We also analyzed the activation of NF-kB and the effects of pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-kB, on M. penetrans LAMPs-induced mouse macrophages apoptosis by indirect immunofluorescence and Western blotting. Our results sug-gested that M. penetrans LAMPs could induce mouse macrophages significant early- and late-stage apoptosis. Agarose gel electrophoresis of the DNA of LAMPs-challenged cells revealed that a ladder-like pattern of migration of DNA indicative of apoptosis. M. penetrans LAMPs could activate NF-kB in mouse macrophages. PDTC could partially inhibit the activa-tion of NF-κB and thus inhibit M. penetrans LAMPs-induced mouse macrophages apoptosis. This study demonstrates that M. penetrans LAMPs may be an important etiological factor due to its ability to induce mouse macrophages apoptosis, which was probably mediated through the activation of NF-kB.

Abstract:Newcastle disease virus (NDV) cause a highly contagious and economically loss in poultry. The amino acid sequence at the protease cleavage site of the fusion (F) protein has been postulated as a major determinant of NDV virulence. In this study, we have examined the role of F protein cleavage site sequence in NDV virulence by use reverse genetics technology. The sequence G-R-Q-G-R-L present at the cleavage site of the F protein of avirulent strain LaSota was mutated to R-R-Q-R-R-F or R-R-Q-R-R-L. The resultant mutated rL-FmF and rL-FmL virus were evaluated by mean death test (MDT) in eggs, intracerebral pathogenicity index (ICPI) and intravenous pathogenicity index (IVPI) tests in chickens. The results showed that the modifica-tion of the F protein cleavage site resulted in a dramatic in crease in virulence from an ICPI value of 0.36 for LaSota to a value of 1.18 for rL-FmF and 1.06 for rL-FmL, respectively. In addition, the mutational viruses showed increase MDT and identical IVPI values to parent virus. the virulence of rescued viruses was greatly enhanced by the amino acid replacements, whether the amino acid on the N terminus of F2 was F or L. On this base, we constructed another two NDVs that expressed a H5 subtype avian influenza virus hemagglutinin (rL-FmF-HA) and green fluorescent protein (rL-FmF-EGFP). the ICPI value of recombinant virus rL-FmF-HA and rL-FmF-EGFP were 0.67 and 1.10, respectively lower than that of rL-FmF. the IVPI of both recombinant vi-ruses still keep 0.00 . The values of MDT for rL-FmF-HA and rL-FmF-EGFP were 117h and 101h, greater than 90h . thus, In-troduction of a foreign gene into NDV genome resulted in growth retardation and attenuation, the decrease degree depended on the nature of foreign protein expressed. These results also indicate that cleavability of the F0 protein is an important determinant for virulence of NDV. NDV can be manipulated in the future for use as a vaccine vector.

Abstract:[Objective] Investigation into the adjuvant effect of the extracellular domain of canine cytotoxic T lymphocyte-associated antigen 4 (CTLA-4). [Methods] We first amplified the cDNA for the extracellular domain from blood lymphocytes using RT-PCR and then amplified the VP2S gene fragment for major antigenic epitopes of the VP2 protein of canine parvovirus (CPV) using PCR. After sequence analysis, we inserted the VP2S fragment into expression vector pQE-31 with or without the coding sequence for the extracellular domain of canine CTLA-4. After transformation of the two recombinant vectors into E. col, we studied recombinant protein expression by isopropyl b-D-1-thiogalactopyranoside (IPTG) induction. Finally, we immunized BALB/c mice with the same dose of the purified protein VP2S or CTLA-4-VP2S and compared their antibody responses by enzyme-linked immunosorbant assay (ELISA) and haemagglutination inhibition (HI) assay. [Results] After 30 cycles of amplification, agarose gel electrophoresis revealed expected PCR products for both gene fragments. Sequence analysis showed that the amplified extracellular domain was 99.2% identical to previously published sequence without mutation in the hexapeptide motif (MYPPPY) for B7 molecule binding. After IPTG induction, the vector-transformed E. coli expressed expected 29-kDa VP2S protein and 42-kDa CTLA-4-VP2S protein. Western blotting showed that both VP2S and CTLA-4-VP2S proteins were recognized by CPV-specific antiserum. After two times of immunizations, the VP2S-specific antibody appeared from week 2 and reached the highest level at week 4 in CTLA-4-VP2S-immunized mice. In VP2S-immunized mice, however, the specific antibody appeared from week 4 and reached the highest level at week 5. The CTLA-4-VP2S-immunized mice had a 100-fold higher ELISA antibody and 10-fold higher HI antibody compared to VP2S-immunized mice. [Conclusion]The extracellular domain of canine CTLA-4 had strong immunoadjuvant effect on its fused protein.

Abstract:Padlock probe was designed based on the sequence of the unique hypothetic protein gene in complete genome of Xanthomonas axonopodis pv. citri (Xac), and amplification primers ware designed according to the universal linking sequence of padlock probe. Detection system of rolling circle amplification (RCA) was established and optimized. Results show that the system could detect Xac and its DNA specifically, while other plant pathogens and bacteria attached on the surface of citrus leaves could not be detected. This indicates that the detection system had its specificity. The detection sensitivity of RCA was 20 cfu/mL for Xac cells and 102copy/mL for cloned DNA fragment, which was slightly higher than the sensitivity of conventional PCR. Leaf samples collected from orange orchards were detected with both RCA and conventional PCR. The result shows that the Xac positive percentage had no remarkable difference between the two methods (P>0.01). Because the universal linking sequence in padlock probe can use same amplification condition, the new technology and detection system can be used to detect diverse plant pathogens simultaneously in plant quarantine and disease pre-symptom diagnosis.

Abstract:[Objective] Based on immunoassay, we developed a method to detect Potato Virus A (PVA) using one-step cytometric bead array (CBA). [Methods] Using fluorescent beads as carriers, we formed the complexes of bead-capture an-tibody-PVA-fluoresceinisothiocyanate (FITC) labeled detection antibody by immunoreaction of double antibody sandwich on bead surface. We measured the fluorescent signals produced from beads and from FITC with a multiparameter flow cytometer. [Results] By optimization test, capture antibody and detection antibody (from PVA detection kit, Agdia, USA) were finally diluted at 1:50 (4ug/mL) and 1:25 to be used in one step CBA, respectively. A total CBA reaction time of 2 h was needed. No cross reactivity with other plant virus similar to potato virus Y, lettuce mosaic virus and tomato ring spot virus were found. Detection sensitivity for positive control sample in one-step CBA was 4 folds higher than that in normal plate double antibodies sandwich enzyme-linked immunosorbent assay (DAS-ELISA). [Conclusion] A one-step CBA method for rapid and sensitive detection of PVA is developed.

Abstract:Epstein-Barr virus (EBV) is an oncogenic herpesvirus associated with a variety of malignancies, including Burkitt’s lymphoma and nasopharyngeal carcinoma (NPC). Functions of most EBV genes have not been determined. The use of bacterial artificial chromosome (BAC) to clone and modify the genome of EBV has enhanced the gene function study in the context of genome. Infectious clones of EBV were previously established by using EBV-BAC plasmid p2089. In order to further investigate EBV mutant biology, an easy and efficient method for gene modification in EBV-BAC was developed and detailed. The kanamycin gene (kan) flanked by recombinase FLP recognition targets (FRTs) was amplified from plasmid pKD13 and inserted into the vector of pcDNA3.1(+). Through the introduction of restriction endonuclease BsmBⅠin PCR primers, NPC-derived LMP1 gDNA containing the full-length ORF was then precisely ligated with kan on pcDNA3.1(+). The linear DNA segment of kan-LMP1 was transformed into E.coli DH10B cells containing p2089 and plasmid pKD46, homologous recombination was subsequently mediated by redαβγ system from bacteriophage l. By this linear transformation and ET cloning, the full-length LMP1 in EBV-BAC (p2089) was replaced by the kan-LMP1. The introduced kan gene in EBV-BAC genome was eliminated specifically by the recombinase FLP when transformed by plasmid pCP20, leaving an FRT scar of 69 bp. The mutant could be identified by antibiotic screening and PCR amplifica-tion on bacteria medium. This method allows the gene of interest to be easily modified alone and then to be introduced into EBV-BAC genome. Following this example of gene substitution, other mutations such as deletion, insertion and point mutation become convenient work, and this improved method can be a potential use of gene modification in other BAC-based herpesvirus genome.

Abstract:By secretion and detection of a series of signaling molecules, bacteria are able to coordinate gene expression as a community, to regulate a variety of important phenotypes, from virulence factor production to biofilm formation to symbiosis related behaviours such as bioluminescence. This widespread signaling mechanism is called quorum sensing. There are several quorum sensing systems described in Serratia. Serratia marcescens AS-1, isolated from soil, had the LuxI/LuxR homologues called SpnI/SpnR. S. marcescens AS-1 produced two kinds of N-acyl-L-homoserine lactones, N-hexanoyl-L-homoserine lac-tone and N-(3-oxohexanoyl)-L-homoserine lactone as signal molecules, which involved in quorum sensing to control the gene expression in response to increased cell density. By gene replacement method, the spnR mutant was constructed, named S. marcescens AS-1R. SpnR acted as a negative regulator for the production of prodigiosin, swarming motility and biofilm for-mation, which were regulated by quorum sensing. Halogenated furanone, known as a natural inhibitor of quorum sensing, could effectively inhibit the quorum sensing of S. marcescens AS-1 but without interrupting AHL-SpnR interaction. All results will be helpful to understand the mechanisms of halogenated furanone inhibition on quorum sensing and the potential applica-tion of halogenated furanone in effectively preventing infection disease caused by Serratia strains.

Abstract:A bacterial strain ME16 was isolated from Jinyang Lake in Taiyuan of Shanxi Province, China. Gas chromatography analysis showed that the strain could use methane as the sole carbon and energy source. Based on 16S rDNA sequence analysis, the strain was identified as Pseudomonas aeruginosa. Effects of inoculum size, temperature, methane content and initial pH of media on cell growth were studied. In addition, we examined the response time of methane gas to dis-solved oxygen and the relationship between consumption of dissolved oxygen and different methane gas content with PVA-H3BO3 immobilized cell of ME16 using electrochemical method. The optimal conditions for cell growth were 2% inoculum size, 25% methane content, 30℃ and pH 6.0. Response time was within 100 s after adding of immobilized cells to reaction system. The linear range of measured methane content was from 0 to 16%, with the correlation coefficient 0.9954. Hence, this strain has potential application in developing of methane biosensor.

Abstract:Taxol has become a widely used clinical anti-cancer drug. Due to the scaricity of Taxus trees, current taxol output cannot meet the requirement of the market. Taxol produced by endophytic fungus fermentation has high prospective. We reviewed advantages of taxol production by fungus fermentation, research advances of isolation, biodiversity of taxol-producing fungi and methods of improved taxol output by endophytic fungus fermentation.

Abstract:Arsenic is widely distributed in the environment. As teratogen, carcinogen or mutagen, it has extremely toxic effect on mammalian health. Recently, as the outbreaks of arsenicosis in many countries such as Bangladesh and China, arsenic toxicity or pollution has been a global problem, severely threatening tens of millions of people’s health. Therefore, studies on the transfer of arsenic toxicity or pollution are important. The threat of pollution and toxicity from the dispersal of naturally occurring and anthropogenic arsenic stimulated extensive studies focusing on the geochemical behaviors, such as mobilization and transformation of arsenic. More evidences suggest that microbes play an important role in the geo-chemical circulation of arsenic. Some microorganisms have evolved to tolerate relatively high concentrations of arsenic by methylation and/or redox. These microbial processes, together with inorganic and physical processes, constitute the global cycle of arsenic. In this article, we review the diversity of microorganisms known to interact with arsenic, and the genes and enzymes involved in these processes. We also briefly discuss the application of arsenic bio-transformation is . Finally, according to the studies in our laboratory, we propose the potential application in medical sciences and its future pros-pects.

Abstract:Bacterial spores are robust and dormant life forms with formidable resistance properties. Spores of the genus Bacillus have been used for a long time as probiotics for oral bacteriotherapy both in humans and animals. Recently, genetically modified B. subtilis spores and B. anthracis spores have been used as indestructible delivery vehicles for vaccine antigens. They were used as vaccine vehicles or spore vaccine for oral immunization against tetanus and anthrax, and the results were very exciting. Unlike many second generation vaccine systems currently under development, bacterial spores offer heat stability and the flexibility for genetic manipulation. At the same time, they can elicit mucosal immune response by oral and nasal administration. This review focuses on the use of recombinant spores as vaccine delivery vehicles.