Abstract:[Objective] The gene (catPLCgl) coding for catechol 1,2-dioxygenase from a fecal microbial metagenome of Nycticebus pygmaeus was cloned and expressed in Escherichia coli BL21(DE3), and the purified recombinant CatPLCgl was characterized. [Methods] The full-length catPLCgl was obtained based on the metagenomic high-throughput sequencing technology, and its amino acid sequence was analyzed. Then catPLCgl was cloned into the pEASY-E2 vector, and characterized by the heterologous expression in Escherichia coli BL21(DE3). [Results] The gene full-length of catPLCgl is 852 bp with a G+C content of 48% and encodes 283 amino acids, with a theoretical molecular weight of 33.56 kD. Characterization shows that the optimal pH was 7.0, and the enzyme activity remained more than 90% after being processed for 1 h at pH between 7.0 and 10.0. The thermal activity of purified recombinant CatPLCgl was optimal at 40 °C at pH 7.0. The enzyme was stable at 25 °C and 40 °C, retaining nearly 100% activity after pre-incubation for 210 h. The kinetic parameters Km, Vmax and kcat values were 24.9 μmol/L, 8.3 μmol/(min·g) and 13.7 s–1 respectively. Fe2+, Hg2+, Cu2+, Triton X-100, SDS and Ag+ dramatically reduced the enzymatic activity, and other metal ions or organic reagents have less effect. [Conclusion] Recombinant CatPLCgl has good temperature stability and alkali resistance.

Abstract:[Objective] Intestinal microbiota affects the function of central nervous system through the “microbiota-gut-brain axis”. Alzheimer’s disease (AD) is considered being related with the microbiota in the intestines. Concentrations of endogenous formaldehyde are positively correlated to the cognitive impairment of AD inpatients. Therefore, we compared the concentration of intestinal formaldehyde between APP/PS1 transgenic mouse model of Alzheimer’s disease and C57BL/6J wildtype mice. [Methods] Take different sections of duodenum, small intestine, cecum, and colon of APP/PS1 transgenic mice (n=8) and those of C57BL/6J wildtype mice (n=9), respectively. Measure the concentrations of formaldehyde in the digestion contents and intestinal walls with HPLC coupled with 2,4-dinitrophenylhydrazine (DNPH) absorptions. [Results] The levels of the cecum formaldehyde in the digestion contents from APP/PS1 transgenic mice were significantly (P=0.036) higher than those from C57BL/6J wildtype mice, but no significant (P>0.05) difference could be observed in the small intestine and colon. Formaldehyde in walls of duodenum, cecum and colon were not significantly different except for the small intestine. That is, the concentration of formaldehyde was observably elevated in small intestinal wall though the change approached to the significant (P=0.052) different. For APP/PS1 mice, the concentration of formaldehyde in cecum either digestion content or wall exhibited the highest, compared with the other intestinal sections. [Conclusion] Intestinal microbiota is one of the important sources producing formaldehyde. The elevated concentrations of formaldehyde in the cecum digestion contents and small intestinal wall of APP/PS1 transgenic AD mice suggested that dysmetabolism of formaldehyde in the intestinal microbiota may be related to age-related cognitive impairment.

Abstract:[Objective] It can provide a theoretical basis for understanding the fermentation mechanism and optimizing the fermentation process that studying on the interaction between different lactic acid bacteria and yeast in light-style liquor and fermentation performance of different strains. [Methods] The light-style liquor fermentation environment was simulated by programmed temperature control and solid state fermentation. In pure culture and co-culture, the changes of physicochemical parameters, viable count and the main metabolites were analyzed. [Results] Saccharomyces cerevisiae YJ1 strain had a higher rate of sugar consumption and produced more ethanol and esters. Lactobacillus plantarum JMRS4 strains had higher rate of sugar consumption and more acid production. Lactic acid bacteria slightly inhibited Pichia kudriavzevii MJ14 biomass and ethanol production, but promoted the production of ethyl hexanoate, ethyl acetate and isoamyl alcohol. In turn, Pichia kudriavzevii MJ14 inhibited three strains of lactic acid bacteria from producing lactic acid and promoted the production of acetic acid. [Conclusion] The actual fermentation process of light-style liquor was simulated by establishing the solid state culture method and simulating the temperature change during the fermentation process. Pichia kudriavzevii MJ14 was slightly inhibited by lactic acid bacteria and could effectively inhibit lactic acid bacteria from producing lactic acid when co-cultured. Saccharomyces cerevisiae YJ1 can produce a variety of flavor substances, which is of great significance to the production of light-style liquor.

Abstract:[Objective] Corynebacterium glutamicum is the main industry strain for production of amino acids, to explore the effects of oxaloacetate anaplerotic reaction mediated by phosphoenolpyruvate carboxylase (PEPC) and phosphoenolpyruvate carboxykinase (PCK) on physiological characteristics and amino acid metabolism, the valine producing strain Corynebacterium glutamicum V1 was studied. [Methods] Overexpressing of pepc encoding PEPC and pck encoding PCK in Corynebacterium glutamicum V1 by means of genetic engineering, the changes of key enzyme activities, fermentation characteristics and main amino acids accumulation were discussed compared with the original strain. [Results] Two recombinant strains V1-pepc (enhanced oxaloacetate anaplerotic pathway) and V1-pck (weakened oxaloacetate anaplerotic pathway) were constructed, both the growth trends were delayed, the total biomass and the consumption of sugar and ammonium basically unchanged; Overexpression of pck, the activity of PCK has 22.8% increased, the yields of alanine, valine, glutamic and arginine were increased by 11.8%, 17.2%, 27.8% and 19.5% respectively; Over expression of pepc, the activity of PEPC increased by 27.5%, while the activity of PC decreased 12.9%, the overall flow of aspartic and glutamic-family amino acids changes little, while the flow of alanine-family reduced by 14.7%. [Conclusion] Alanine-family amino acids are greatly influenced by this pathway while aspartate-family not.

Abstract:[Objective] Antibiotic resistance is a severe public health problem. Recently, the relationship between bacterial metabolic regulation and antibiotic efficacy has been proposed in several pathogens. In the present study, we explored the effect of adding additional chemicals on drug susceptibility of Vibrio parahaemolyticus. [Methods] We studied the phenotypic change and compared the survival of V. parahemolyticus after treatment with antibiotics and different chemicals. The experimental results were conformed with carbonylcyanide-p-chlorophenyl hydrazine (CCCP). [Results] These results indicated that specific chemicals effectively potentiate kanamycin to eliminate multidrug resistant V. parahemolyticus. Among them, the addition of exogenous glucose could significantly enhance the sterilization ability with subinhibitory concentrations of kanamycin, but without effect on other antibiotics. The enhancement of antimicrobial susceptibility of Vibrio parahaemolyticus caused by exogenous chemicals could be eliminated after treatment with CCCP. [Conclusion] The sensitivity of V. parahemolyticus to aminoglycosides can be improved by regulating the metabolism of bacterial cells. Therefore, we present a novel approach in fighting against multidrug resistant V. parahemolyticus with practical application value.

Abstract:[Objective] We studied the growth characteristics of Haloferax volcanii WFD11 cultivated on a number of aromatic acids as carbon sources to reveal the possible difference between bacteria and archaea in aromatic acids degradation. [Methods] The putative gentisate 1,2-dioxygenase gene was cloned and the enzyme heterologously expressed, purified and functionally identified before determining its key enzyme parameters. We measured the growth of H. volcanii WFD11 in halophile growth medium minimal medium containing one of the six aromatic acids (4 mmol/L) separately as sole carbon source. The intermediate from 3-hydroxybenzoic acid catabolism was determined using high performance liquid chromatography. The putative gentisate 1,2-dioxygenase gene, designated hagA, was heterologously expressed in H. volcanii H1424, and HagA was purified by affinity chromatography on an Ni2+ chelating column of rapid purification system. HagA was functionally identified based on its specific activity to catalyze the ring cleavage of gentisate using ultraviolet spectrophotometer. The expression type of hagA was revealed by real-time PCR. [Results] Strain WFD11 could use 4 mmol/L 3-hydroxybenzoic acid (3HBA) and 3-hydroxyphenylpropionic acid (3HPP) as sole carbon source for growth, but not on 4 mmol/L benzoic acid (BA), 2-hydroxybenzoic acid (2HBA), 4-hydroxybenzoic acid (4HBA), 3-phenylpropionic (3PP). Gentisate was determined as the intermediate during 3HBA catabolism. The cell extract of H. volcanii WFD11 catalyzed the ring cleavage of gentisate to maleylpyruvate. Purified HagA exhibited a specific activity of 0.024 8 U/mg of gentisate 1,2-dioxygenase, without Fe2+. Real-time PCR proved that hagA was constitutively expressed in strain WFD11. [Conclusion] This study provides the basis to further explore the difference between bacteria and archaea in aromatic acids degradation.

Abstract:[Objective] In order to isolate high-purity and intact gas vesicles from the cells of bloom-forming cyanobacterium Microcystis aeruginosa PCC 7806, and to identify structural proteins of gas vesicles. [Methods] Osmotic shock combined with lysozyme treatment and low speed centrifugation were used to isolate and purify gas vesicles. The purity, integrity and characteristic shape of gas vesicles were examined by negative staining and transmission electron microscope. The structural proteins of gas vesicles were detected and identified by SDS-PAGE electrophoresis and LC-MS. [Results] Electron microscopic examination indicated that the isolated gas vesicles had high purity and showed good integrity. They took a cylinder shape with conical end caps and had a similar diameter of about 120 nm and the variable lengths from 500 to 1 500 nm. GvpA and GvpC identified by SDS-PAGE electrophoresis and LC-MS were two main structural proteins of gas vesicles. [Conclusion] Our findings would have great significance to reveal the fine structure of gas vesicles and to further study the buoyancy regulation mechanism of bloom-forming cyanobacteria.

Abstract:[Objective] To study the flocculation effect of bacterial strain xn-1 on water bloom causing species-Microcystis aeruginosa, to control water bloom. [Methods] Flocculation bacterium was isolated from phycosphere based on plate spread and streak technique; 16S rRNA gene was applied to determine the evolutionary status. Flocculation mechanism was confirmed by addition of different metal ions as coagulants. Bioflocculant was obtained by gradient alcohol precipitation. Microplate reader was used to study flocculation activity. [Results] Strain xn-1 was determined as a species of the genus Shinella, designated as Shinella sp. xn-1. Strain xn-1 exhibited high flocculation activity on M. aeruginosa with adding Ca2+ as coagulants, and the flocculation activity was originated from extracellular supernatant, showing high flocculation efficiency with the concentration of 3.0%. Bioflocculant isolated from extracellular supernatant could exhibit high flocculation effect with the addition of 0.5 g/L, and the algal flocs became huger with the increase of processing time. [Conclusion] Shinella sp. xn-1 shows high flocculation activity on M. aeruginosa through secreting extracellular bioflocculant, and the flocs with large volume are formed under the flocculation effect. This study is a useful option to control water blooms in the future.

Abstract:[Objective] An efficient malachite green degradation bacterial strain was isolated from the actived sludge sample collected from wastewater-treating system of dye manufacturer, and the toxicity of malachite green before and after decolorization was contrasted through some methods. [Methods] A decolor bacteria was isolated by dilution plating procedure and was then identified by scanning electron microscope (SEM) and 16S rRNA gene analysis. The toxicity of malachite green before and after decolorization was evaluated through biological toxicity tests using Chlorella and Vicia faba as test material. [Results] The strain separated from the wastewater-treating system of dye manufacturer was identified as Klebsiella sp. JD on the basis of 16S rRNA gene analysis. Klebsiella sp. JD biochemical colony which was gray and viscous shows a regular circle shape. With the touch of inoculation loop, the colony was draw into wire easily and the wire had a smooth surface. By comparing with the growth rate and inhibiting rate of Chlorella, the MCN‰ and PI of Vicia faba, it could be found that the toxicity of malachite green decreased after decolorization. [Conclusion] A malachite green degradation bacterial strain is isolated in this research. The efficient strain can reduce the toxicity of dye, which has a practical significance in the remediation of dye contaminated water.

Abstract:[Objective] Greater Khingan forest is one of the largest forest areas in China. There are many studies on plant diversity along forest succession in this area, but few studies on microbes. This research studied the impact of forest succession on soil microorganism diversity in Greater Khingan Mountains, which could provide a more comprehensive understanding of the impact of the natural forest protection project on biodiversity. [Methods] Effects of forest succession on soil bacterial diversity were analyzed by a space-trade-for-time experiment. The typical natural successional sequence after fire in Greater Khingan forest is fire-burned land (LG-BA), shrub (SHR), birch forest (BP), mixed forest of larch and birch (BP-LG), and larch forest (LG-OM). 0?10 cm top mineral soil samples were collected on forest plots and the bacterial community structure and diversity were determined with Illumina MiSeq high-throughput sequencing technique. [Results] The number of bacterial species from low to high was in the sequence of the larch and birch mixed forest, shrub forest, larch forest, and birch forest. Following forest succession, the Simpson diversity index firstly increased and then decreased. The Shannon index followed the dynamic trend of increase, decrease and increase pattern. The change of OTU (Operational taxonomic unit) abundance was relatively gentle in the succession processes, indicating that the species change was small. The phyla of soil bacteria were mainly Proteobacteria, Acidobacteria, Actinobacteria and Planctomycetes in all of the successional stages, all of them followed the change trend of increase in the first succession stage and decrease in the later stage. PCA analysis showed that bacterial communities were different in the varied successional stages. RDA analysis showed that organic matter, total nitrogen, total phosphorus and pH impacted soil bacterial community. [Conclusion] Following forest succession, the species of soil bacteria was changed in Greater Khingan forest. The most common soil bacteria communities differed across natural succession, varying as a function of soil SOM, total potassium, total phosphorus, and pH.

Abstract:[Objetive] Chaka Salt Lake is a famous natural and crystal salt lake on the Qinghai-Tibet Plateau, having unique halite deposits and abounding in edible salt. There are abundant halophilic bacteria resources and potential species in the salt lake environment. The community structure and species diversity of bacteria and archaea remains unknown. [Methods] Microbial community and diversity of water and sediment mixture samples were investigated by the 16S rRNA V3?V5 region gene based on an Illumina high-throughput sequencing platform. [Results] Totally 117 192 and 110 571 valid sequences of bacterial and archaeal 16S rRNA gene were generated respectively in this study. Results showed that the species annotation OTU (Operational taxonomic unit) numbers of bacteria and archaea were 421 and 317, respectively, belonging to definite taxonomic bacteria of 14 phylum 28 classes 170 genera and classified archaea of 5 phylum 4 classes 34 genera. Bacterial dominant groups were Firmicutes (68.37%), followed by Proteobacteria (20.49%). The bacterial dominant populations were Bacillus (41.94%), Oceanobacillus (8.03%), Pseudomonas (7.67%), Halanaerobium (7.42%) and Lactococcus (7.38%) in turn. Furthermore, archaeal dominant group was Halobacteria in the Euryarchaeota, and dominant archaea populations were Halonotius (17.21%) and Halorubrum (16.23%). [Conclusion] This study revealed the community structure and the species diversity of bacteria and archaea in Chaka Salt Lake. These results could provide significant theoretical references for the exploitation and utilization of microbial resource.

Abstract:[Objective] To provide a foundation for new resource mining of the alkalophilic Bacillus-like species and development of microbial agents, we studied the species distribution and diversity of Bacillus-like isolated from soil samples in Kekexili of Qinghai Province. [Methods] Alkalophilic Bacillus species were isolated from soil samples using the cultural method on Horikoshi I medium and preliminarily identified based on 16S rRNA gene sequences. Then, strains with ability of protease-, cellulases- and xylanase-producing activity were screened using transparent zone method. [Results] A total of 66 strains of alkalophilic Bacillus species were obtained and identified as 22 species belonging to 6 genera, Bacillus, Gracilibacillus, Halobacillus, Jeotgalibacillus, Paenibacillus, and Psychrobacillus, by 16S rRNA gene sequences similarities analysis. The genus Bacillus was the dominant bacteria. There were 2 new potential species of alkalophilic Bacillus with 16S rRNA gene similarities 97.00% and 98.65%, respectively. Three enzymes-producing strains accounted for 95.00% of all isolates, including 55 strains with protease activity, 27 strains with cellulase activity, and 8 strains with xylanase. [Conclusion] There were rich resources of alkalophilic Bacillus species and abundant enzyme-producing strains in Kekexili of Qinghai Province, which provided a great potential of exploitation of alkaliphilic Bacillus species.

Abstract:[Objective] To examine the catalytic characteristics of gold nanoparticles (AuNPs) biosynthesized by Trichosporon montevideense WIN. [Methods] The characteristics of gold particles synthesized by incubation strain WIN with 1 mmol/L, 2 mmol/L and 4 mmol/L HAuCl4 were investigated. In addition, the AuNPs were biosynthesized by active and inactive cells of strain WIN, respectively. The morphology and particle size of the synthesized AuNPs were analyzed, and the catalytic activity of AuNPs for reduction of nitro aromatic compounds was also evaluated. [Results] When the concentration of HAuCl4 was 1 mmol/L, AuNPs were produced by strain WIN, while AuNPs and large gold particles were formed with 2 mmol/L and 4 mmol/L HAuCl4. The active and inactive cells of strain WIN could synthesize AuNPs based on the analyses of UV-vis spectroscopy and transmission electron microscopy. The synthesized AuNPs were mainly spherical, and some triangle, hexagon and parallelogram. The size of AuNPs synthesized by active cells of strain WIN ranged in 3 nm?252 nm with an average size of 45.2 nm, while the size range and average size of AuNPs synthesized by inactive cells of strain WIN were 1 nm?271 nm and 38.3 nm, respectively. The AuNPs synthesized by active and inactive cells of strain WIN could effectively catalyze the 4-nitrophenol reduction with the catalytic rate constants of 2.76×10?3 s?1 and 4.84×10?3 s?1, respectively. [Conclusion] Trichosporon montevideense WIN could be used to synthesize AuNPs and the biosynthesized AuNPs exhibited good catalytic properties, which showed a potential application in catalytic removal of the refractory pollutants in environment.

Abstract:[Objective] We studied the distribution and potential function of Rib protein, a large bacterial cell surface protein founded in Lactobacillus reuteri, in different lactobacilli strains. [Methods] Primers were designed according to the 5′ non-repeat regain sequence of rib gene in L. reuteri ATCC55730, to PCR rib gene and heterologous expression. Truncated Rib protein from L. reuteri was expressed in Escherichia coli. The recombinant protein was purified and used for polyclonal antibody preparation. Western blot was done in subcellular localization analyses of Rib and Rib like protein detection. [Results] Western blot showed that Rib protein mainly distributed in the L. reuteri bacterial cell wall. Both PCR and Western blot analyses showed that Rib like protein was detected in 11 lactobacilli strains with different size. [Conclusion] Rib like protein is a probable widely distributing cell surface protein in lactobacilli strains, and may play a role in the adhesion of these lactobacilli on the host gut.

Abstract:[Objective] Antagonistic endophytic bacteria against Monilinia fructicola were screened from the roots of peach trees. The inhibitory mechanism was studied at cellular level. [Methods] The confront-culture method was adopted to screen endophytic bacteria against M. fructicola. The obvious features of antagonistic strains were determined by cell morphological observation, physiological and biochemical characteristics. Strains were identified by 16S rRNA gene sequencing and phylogenetic analysis. The effect of biological control was tested through the experiment of fruits in vitro. The change of mycelia, spore morphology and the internal structure of cells was observed under electron microscope. [Results] By secondary screening, three strains had obvious and stable effect antagonist M. fructicola, these strains were identified as Bacillus subtilis. The experiment of fruits in vitro showed that the three strains inhibited the growth of M. fructicola obviously. Results of microscopic analysis show that the mycelia inhibited by the antagonistic bacteria were obviously attenuated, with severe disorder, twining and knotting. Most spores were shriveled, enlarged and rupture. In cells of the pathogen inhibited by the antagonistic bacteria, the phenomena of cytoplasm exosmosis, protoplast shrinkage and condensation, and a large amount of cavities were observed. [Conclusion] The three strains of the endophytic bacteria screened from the roots of peach trees had effective inhibitory on the growth of M. fructicola, these strains could be served as new resources against M. fructicola.

Abstract:[Objective] We explored plant growth promoting rhizobacteria with strong activity of resisting nickel and secreting siderophore, and studied their effect on promoting peanut plant growth and absorbing nickel. [Methods] Strains with strong siderophore secreting capacity were isolated from peanut rhizosphere by using qualitative and quantitative test of CAS (chrome azurol S) medium. Siderophore secreting strains were identified by similarity and phylogenetic analysis of 16S rRNA gene. Tolerance of siderophore secreting strains to nickel was measured by beef extract-peptone medium supplemented with nickel ion. In the pot experiment of peanut, effects of siderophore secreting strains on peanut plant was analyzed by measuring shoot height, root length, biomass and the content of nitrogen, phosphorus, potassium and nickel in peanut plant. [Results] Five Bacillus strains with siderophore secreting capacity were isolated from peanut rhizosphere. Bacillus sp. HSGJ1 showed the strongest siderophore secreting capacity among the five strains. It secreted 156.56 mg/L of siderophore after 2 days. Bacillus sp. HSGJ1 showed strong tolerance to nickel with 150 mg/L of minimum lethal concentration. HSGJ1 could promote plant growth, increase the biomass and nitrogen, phosphorus and potassium contents of peanut, and decrease the nickel content in the root and shoot of peanut plant in 50 and 100 mg/kg of Ni2+ in pot soil. [Conclusion] As a good plant growth promoting rhizobacterium, the siderophore secreting Bacillus sp. HSGJ1 can be applied for planting crop in the nickel contaminated soil to improve crop tolerance under nickel stress and decrease nickel accumulating in crop. Therefore, Bacillus sp. HSGJ1 shows good application value.

Abstract:[Objective] Isolated bacterial strains which can resistance to root-knot nematodes and promote the growth of plant under the sub-low temperature condition. [Methods] Joint method was used to screen the bacterial strain, the joint method include nematodes resistance test, indoor low temperature resistance test, antagonism test and pot experiment. Phenotypic characteristic, physiological and biochemical characteristics and 16S rRNA gene sequencing method were used to identify the strains which passed screening method. [Results] 297 different bacteria and actinomyces strains were isolated from the soil of tomato and cucumber rhizosphere which are often seriously in root-knot nematode disease; After analysis the nematodes resistance rate, 9 strains which have more than 70% corrected death rate to the nematodes were isolated; A strain called S205 was isolated, it have excellent function in prevention and cure of root-knot nematode, soil-borne pathogens and promoting plant growth under sub-low temperature; Strain S205 was classified as Streptomyces antibioticus. [Conclusion] This research had isolated a biocontrol strain S205 which have the property of resistance root-knot nematode and promoting plant growth under sub-low temperature. The research is significant in prevention of root-knot nematode disease under sub-low temperature.

Abstract:[Objective] To isolate and characterize bacteria from soy sauce moromi and evaluate their potential applications in soy sauce production. [Methods] The dominant or specific bacterial strains will be isolated from Japanese-style soy sauce moromi. And their capabilities in salt tolerance, proteinase secretion and production of organic acid, amino acids, volatile compounds under high salt condition will be assessed. [Results] A total of nine strains belonging to the genus of Weissella, Pediococcus, Lactobacillus, Bacillus, Tetragenococcus and Staphylococcus were isolated from soy sauce moromi. Weissella paramesenteroides CQ03, Pediococcus acidilactici JY07, Pediococcus pentosaceus JY08, Staphylococcus sp. JY09 and Tetragenococcus halophilus MRS1 were found to be salt-tolerant strains. Bacillus amyloliquefaciens B2 exhibited stronger capability in secretion of protease and glucoamylase. W. paramesenteroides CQ03 produced more umami tasting amino acids than other isolates. Both T. halophilus MRS1 and S. sp. JY09 retained high activities in synthesis and accumulation of volatile compounds. The potential capability in organic acids production by T. halophilus MRS1 was also detected. [Conclusion] Nine strains that belong to different species with potential capability in promoting raw materials hydrolysis and improving soy sauce aroma were obtained. The results demonstrated their benefit for shortening fermentation duration and improving the quality of soy sauce.

Abstract:[Objective] Xinjiang traditional fermented food, Naan is one of the traditional staple food for Uygur. There are different dough fermentation methods for different living regions of the Uygur family. To explore traditional Naan sourdoughs from Toksun in Turpan county for culturable microbial components analysis and the dough volatile aroma composition analysis in the fermentation process. [Methods] After using pure culture method, 16S rRNA gene sequence analysis and 26S rRNA D1/D2 region gene sequence analysis were taken place. We used headspace solid phase micro extraction-emperament (HS-SPME/GC-MS) for the dough microbial diversity and volatile aroma components were detected. [Results] From two samples we isolated 9 strains of Lactobacillus sanfranciscensis, 4 strains of Weissella cibaria, 11 strains of Basillus amyloliquefaciens, 1 strain of Bacillus shakletonii, 1 strain of Bacillus subtills and 10 strains of Saccharomyces cerevisiae. However, no culturable yeast strain was separated from sample 2, which has attracted our attention. By using GC/MS, we identified lipids, alcohol, aldehydes in two groups of sour dough’s main aroma components. [Conclusion] Our results shows that the predominant bacteria is Bacillus amyloliquefaciens and Lactobacillus sanfranciscensis in the Toksun Turpan traditional dough. Due to the solution of starch in the dough bacillus has inhibitory effect to the fungus, the dough can develop yeast were suppressed, but it does not affect its many kinds of flavor substances. The dough with karez water produce a variety of aromatic substances relatively large percentage than with tap water does.

Abstract:[Objective] To investigate the role of Salmonella genomic islands of unknown functions for pathogenicity and also to identify new islands associated with Salmonella virulence. [Methods] Using Salmonella enteric serovar Typhimurium (S. Typhimurium) ATCC 14028 as wild-type strain, we constructed mutants for seven islands of unknown functions (STM14_0667?0673, 2682?2687, 2885?2891, 3721?3728, 4247?4253, 4823?4828, 5331?5341) by employing the λ Red recombinase method. Through invasion assays, macrophage replication assays, and mice experiment, we compared the virulence of the mutant strains to that of the wild-type 14028. [Results] Compared with wild-type strain, Δ2682?2687 and Δ5331?5341 significantly decreased their invasion ability to epithelial cells (P<0.01); Δ2682?2687, Δ2885?2891 and Δ5331?5341 significantly decreased their replication ability in macrophages, and also showed decreased virulence to mice, with the bacterial counts of mutants in intestine, liver and spleen were less abundant than that of the wild-type strain (P<0.05). No significant differences in invasion ability, replication ability, and virulent to mice were observed between wild-type strain and the other four mutant strains (Δ0667?0673, Δ3721?3728, Δ4247?4253 and Δ4823?4828). [Conclusions] This study found three islands of unknown functions contributing to S. Typhimurium pathogenicity, and provided powerful tools for the further research on the regulatory systems and functions of these islands.

Abstract:[Objective] To determine the cause of Chlamydia muridarum-induced pathology in urogenital tract of mice with various genetic background, and to explore the mechanism of inflammatory cells’ dynamic changes in pathological difference of mice infected with chlamydia. [Methods] Each of DBA/2J and A/J mice was inoculated via intrauterine route with 2×105 inclusion forming units (IFUs) of live C. muridarum organisms. Mice were sacrificed on 60 days post infection, and the severity of oviduct hydrosalpinx from each mouse was examined visually. The severity of inflammation and pathologies were scored under microscope. Vaginal swabs were taken on 3, 7, 14, 21, 28, 35, 42, 49, 56 and 60 days post infection from each group of mice and the total number of IFUs per swab was calculated. Five mice per group were sacrificed on 14 days post infection, each section of urogenital tract was made into homogenates for measuring the number of IFUs and the level of cytokines per sample. Meanwhile, 5 mice per group were sacrificed each time on 3, 28 and 35 dpi for diagnosis of the type and dynamic changes of inflammatory cells in the diseased tissues. [Results] Two groups of mice had statistically significant differences in hydrosalpinx incidence and severity of dilation whereas no statistically difference in the scores for the severity of inflammation. DBA/2J and A/J mice displayed same in number of chlamydial IFUs and pathology positive mice rate. The level of some inflammatory cytokines but not the number of IFUs detected in oviduct and ovary homogenate on 14 days had statistically difference. In early stage of infection neutrophils in pathological tissues increased in both DBA/2J and A/J mice whereas no obvious difference in two results. Many eosinophils occurred in pathological tissues of DBA/2J mice on 28 days and displayed statistically difference with A/J mice on 35 days. [Conclusion] The pathological difference of urogenital tract from DBA/2J and A/J mice with intrauterine inoculation of C. muridarum may have relationship with eosinophils-involved inflammatory reaction.

Abstract:[Objective] Acquire the polyclonal antibody against non-structural protein ORF4 of cyprinid herpesvirus 2, and reveal the tissue distribution pattern of ORF4 protein during the virus infection. [Methods] The ORF4 structure was analyzed by SMART and BLASTx. The ORF of ORF4 was amplified from viral genomic DNA and cloned into plasmid PGEX-4T-3. The recombinant plasmid was transformed into Escherichia coli BL21(DE3) for recombinant protein production after induction by IPTG. The expressed recombinant protein was then purified by affinity chromatography and the purified protein was used to immunize New Zealand rabbits to obtain the anti-ORF4 polyclonal antibody. The specificity of the anti-ORF4 polyclonal antibody was confirmed by Western blot. Furthermore, real time PCR analysis was employed to monitor the genomic replication level in various tissues of virus-infected Carassius auratus gibelio including muscle, brain, gill, spleen, liver pancreas, heart, kidney. And the tissue distribution pattern of ORF4 in infected Carassius auratus gibelio was subsequently analyzed by Western blot. [Results] The expressed recombinant ORF4 protein in bacteria was detected at 65 kD as expected. Immunoassays suggested that the home-made antibody can specially recognize either the recombinant protein or endogenous ORF4. It proved that the ORF4 was mainly distributed in the kidney, spleen and gill in vivo, which was in consistence with the high level of virus replication in these tissues revealed by real time PCR assay. [Conclusion] Non-structural viral protein ORF4 might involve in efficient viral replication, which could serve as a marker protein for active virus infection. This study paved the way for studying the mechanism of ORF4 in the process of cyprinid herpesvirus 2 infection.

Abstract:[Objective] Some of mangrove endophytic fungi inhabitated in special ecological which were enabled to secrete novel and biologically active compounds. In this study, an endophytic fungus HQD24 with antioxident activity was isolated from Rhizophora mucronata in Dong Zhai Gang-Mangrove Garden on Hainan Island and its antioxidant activity of crude extracts were evaluated. [Methods] Strain HQD24 was identified as Aspergillus fumigatus based on the morphological characteristic and ITS rDNA sequence analysis. Fermentation substrate were extracted with petroleum ether, chloroform, ethyl acetate and n-butanol successively. The antioxidant activity of were evaluated using radical scavenging activity on DPPH (2,2′-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonicacid)), reducing Fe3+ capacity, chelating Fe2+ ability and superoxide radical-scavenging activity. [Results] The crude extract and all fractions possessed antioxidant and radical-scavenging activities in different assays. ABTS and superoxide radical-scavenging abilities were enhanced with the increase of the extract concentration. Chloroform fraction exhibited higher scavenging ability on ABTS radical reaches 71.92%, n-butanol fractions was found to be the most effective in superoxide radical scavenging reaches 62.36% with concentration of 1.5 g/L. The results indicating most of the antioxidant compounds of HQD24 are distributed in the chloroform and n-butanol fractions, followed by the ethyl acetate, and petroleum ether fraction. [Conclusion] Strain HQD24 was identified as Aspergillus fumigatus, which to be a promising resource with antioxidant activity for further investigation

Abstract:Phenylurea herbicides, ?rst marketed in the mid-20th century, have become one of the most important classes of herbicides and have been widely used for controlling both annual grasses and broad-leaf weeds. With the continuous application of phenylurea herbicides, the residue of these herbicides in the environment was beyond the threshold concentration imposed by legislation, and their environmental hazards gradually became more and more serious. Thus, the environmental behaviors of phenylurea herbicides, such as adsorption, migration, and degradation, have received considerable attention. Researches show that the metabolism of N,N-dimethyl-substituted phenylurea herbicides are mainly initiated by consecutive N demethylation events, followed by hydrolysis of the urea side chain, while the N-methoxy-N-methyl substituted phenylurea herbicides are degraded via cleaving directly the urea side chain by bacteria. The fungal degradation pathways of phenylurea herbicides are more complex, therefore further studies are needed. In this article, we summarized the latest progress in the research of phenylurea-degrading microorganisms and their metabolic pathways, which will provide the reference for the feasible bioremediation strategy on phenylurea herbicides contaminated environments.

Abstract:Compared with traditional methods, removal of heavy metals from water by biosorption is a more economic and environmental friendly technology. Microalgae have become a potential biological adsorbent for their low cost and high adsorption rate. To evaluate the potential application value of microalgae in the removal of cadmium, the mechanism of microalgae resistance to heavy metals needs to be analyzed. This review summarizes the microalgae species resistant to Cd, the effects of Cd on microalgae growth, photosynthesis and cell structure, the mechanism of extracellular adsorption and intracellular accumulation, and the cadmium resistance gene regulation. It is of reference value for further heavy metal removal researches.

Abstract:In the early, the researchers had explored the symbiotic mechanisms of lactic acid bacteria and yeasts from the perspectives of nutrition. In the process of mixed culture, there are not only complementary mechanism, but also can promote or inhibit each other. As the LuxS/AI-2 mediated quorum sensing system (QS) of the discovery and development, a lot of researchers from the perspective of quorum sensing system to explore the information of communicate between lactic acid bacteria and yeasts at present. This article has elaborated the current research progress of symbiotic mechanism of lactic acid bacteria and yeasts from two perspectives of nutrition and signaling molecules.

Abstract:[Objective] To evaluate the efficacy of loop-mediated isothermal amplification (LAMP) based kits for rapid detection of Escherichia coli O157:H7. [Methods] Specificity, sensitivity, repeatability and stability of the kits were evaluated, and the result detected by LAMP kits was compared with the detection result by traditional microbiological detection method in practical samples. [Results] All E. coli O157:H7 standard strain samples were detected positive, while all non-E. coli O157:H7 samples were detected negative, showing that the detection had no cross reaction. The minimum test limit of the kit was 29 CFU. Detection specificity, accuracy and sensitivity of the kit were preeminent, and the detection result was highly consistent with that obtained by traditional microbiological detection method. The detecting repetition rate for high concentration of target bacteria and negative bacteria samples detected by the kits was 100%, and the inter-batch testing repetition rate for low concentration of target bacteria samples was 94%. This kit could be preserved for more than 9 months at 4 °C, and it remained its efficacy after a variable temperature storage for more than 72 h. [Conclusion] The kit has high specificity, sensitivity, repeatability and easy storage characteristics, which make it applicable for rapid detection of E. coli O157:H7.