Abstract:[Objective] Lomofungin is a phenazine antibiotic with broad-spectrum anti-bacterial activity and is biosynthesized by Streptomyces lomondensis. In the lomofungin producing strain, S. lomondensis S015, a methyltransferase gene lomo3 at the downstream of the phenazine biosynthesis core gene cluster was studied. [Methods] we inactivated lomo3 by in-frame partial deletion and obtained strain S015Δlomo3. Complementary strain S015Δlomo3::lomo3 was then constructed. To investigate the function of lomo3, we analyzed the metabolites in the fermentation broth of S015, S015Δlomo3 and S015Δlomo3::lomo3. [Results] Inactivation of lomo3 in S. lomondensis S015 resulted in the absence of lomofungin production. The lomo3 complementary strain S015Δlomo3::lomo3 regained the biosynthesis of lomofungin. [Conclusion] This methyltransferase gene lomo3 plays an important role in the biosynthesis of lomofungin. The information obtained in this study laid a theoretical foundation for the biosynthesis of lomofungin.

Abstract:

Abstract:[Objective] The deterioration of grasslands has become one of the major environmental problems in China. Both soil microbial biomass and extracellular enzyme activity are important indices, influencing soil nutrients and environmental quality. We aim to reveal the effect of grassland deterioration on soil microbiological characteristics along a depth profile. [Methods] The Inner Mongolia steppe was selected due to its typical deterioration features. We took samples at different depths (0 to 100 cm) from four grasslands including mature grassland, moderately deteriorated grassland, severely deteriorated grassland and extremely deteriorated grassland. We measured soil microbial biomass and the activity of extracellular enzymes involved in carbon and nitrogen cycling. [Results] Microbial biomass and enzyme activity at the topsoil layer showed the same trend in different deteriorated grasslands: mature grassland > moderately deteriorated grassland > severely deteriorated grassland > extremely deteriorated grassland. The differences between the 10?20 cm and topsoil in microbial biomass and enzyme activity were reduced with deterioration, and the microbial biomass and enzyme activity at the 10?20 cm layer were higher than that at the topsoil in the extremely deteriorated grassland. [Conclusion] Microbial biomass and enzyme activity at the topsoil layer decreased with grassland deterioration. When the deterioration of grasslands became more severe, the differences in soil microbiological characteristics between the surface and the 10?20 cm soil were less. These results provide a new method for assessing the degradation of grasslands, and thus offer important theoretical bases for the restoration of degraded temperate grassland.

Abstract:

Abstract:[Objective] To optimize the process for transesterification reaction in biodiesel production by the synergistic biocatalyst in high water content system. [Methods] The synergistic biocatalyst of Candida antarctica lipase B (CALB) and Rhizopus oryzae lipase (ROL) were expressed and secreted in Pichia pastoris using genetic engineering techniques. The single factor experiment was used to optimize the process conditions, and the methyl ester (ME) yield was used to evaluate the transesterification ability of synergistical biocatalyst. [Results] The maximum ME yield of 93% could be achieved using 16 U/g oil combined with mixed lipase (CALB:ROL=7:3) for the methanolysis. The molar ratio of methanol to oil is 4:1 (initial methanol/oil molar ratio 2:1 and 1:1 at 12 h and 24 h, respectively), water content 30%?60% (W/W) (based on oil weight), temperature 40 °C for 29?34 h. [Conclusion] This synergistic catalytic system is environmental friendly. Furthermore, both the consumption of lipase and reaction time were decreased more than 50% compared with the conventional enzymatic preparation of biodiesel. Therefore, this study provides an effective way to decrease the cost of biodiesel preparation and also has great potential in biodiesel industry.

Abstract:[Objective] We explored the fungal community composition on mural surface, to analyze the major environmental factors that induce the explosion of fungal disease, and to provide the basis for the scientific conservation of murals. [Methods] Mural samples with and without whitish moldy necrosis were carefully and separately collected by sterile scalpel. The Scan Electronic Microscope (SEM) was used to analyze microcosmic features of fungus that caused mural biodeterioration. By the extraction of total genomic DNA, the following steps should be the amplification of fungal ITS region, clone library construction, sequencing, and phylogenetic analysis, thereafter the fungal community composition and structure characteristics were clarified. Combined with temperature and relative humidity (RH) monitoring, the environmental factors related to fungal growth can be figure out. [Results] A large amount of mycelia existed on mildewed murals, the volume of conidia ranged among 1.5?2.0 μm multiplied by 1.0?1.5 μm. Most of clone library sequences in mildewed murals were much similar to genera Engyodontium and Acremonium, of these fungi Engyodontium album was a dominant fungus (98.1%); however, sequences from mural samples without mildew were more similar to genera Penicillium, Aspergillus, Alternaria, Candida, Chaetomium and Engyodontium, in which Penicillium laeve was a dominant species (77.4%). All sequences belonged to Ascomycota in our study. The temperature below the tomb tunnel varied from ?0.3 °C to 17.6 °C, and RH varied mostly from 80% to 100%. [Conclusion] The fungal community composition in the moldy murals was distinct different from murals without apparently moldy necrosis. Engyodontium album was the dominant disease fungus which caused mildew of murals. Perennial higher RH below the tomb tunnel must be the primary environmental factor that induced mildew. As a result, it is necessary to carry out some salvage protection and certain environmental control measures for conservation of ancient murals in this archaeological site.

Abstract:[Objective] To identify strain T61 which was isolated from Tibetan soil and analyze its radiation resistance. [Methods] First, investigate the morphological and biochemical characteristics of T61; Second, amplify the sequence of 16S rRNA gene and construct the phylogenetic tree; Third, determine compositions of fatty acids, DNA G+C content and DNA-DNA hybridization; Finally, analyze T61 survival curve after exposure to UV radiation. [Results] T61 cells were rod-shaped, 2 μm in length, 1 μm in diameter, gram-positive and endospore-forming. Strain T61 had a G+C content of 38.02%. The main Fatty acids were C14:0 iso, C15:0 iso and C15:0 anteiso. Phylogenetic analysis of the 16S rRNA gene showed that strain T61 had 99.93% and 99.53% similarities with Bacillus aryabhattai B8W22T and Bacillus megaterium IAM13418T, respectively. At the whole genome level, the DNA-DNA relatedness between T61 and Bacillus aryabhattai B8W22T was 81.4%, but only 50.3% with Bacillus megaterium IAM13418T. D10 values of T61 after exposure to UV was 100 J/m2, much higher than those of radiation-sensitive Escherichia coli K12 and B. subtilis. [Conclusion] Strain T61 was highly resistant to UV radiation. It was identified as Bacillus aryabhattai species, and was proposed the name Bacillus aryabhattai T61.

Abstract:[Objective] objectives of this study were to isolate and identify algicidal bacteria and scenedesmus, then analyze the inhibition mechanism on scenedesmus by algicidal bacteria. [Methods] Streak culture and physio-chemical properties were used to purify and identify algicidal bacteria respectively. The methods in “Microscopy and Chinese common freshwater planktonic algae” were used to isolate and characterize scenedesmus. The items including chlorophyll a, DO, scenedesmus cells, alga protein expression, special matter of algal inhibition were analyzed to clarify the influences of algicidal bacteria on scenedesmus. [Results] Four algicidal bacteria (R1?R4) were isolated and identified their genus of Bacillus sp. based on their physi-chemical properties. Algicidal bacteria R1 was proved for its most inhibition effects on scenedesmus. The inhibition of chlorophyll a was 65%; DO was 6.5 mg/L, far below to 10.4 mg/L obtained by the sole-culture of scenedesmus; The alga protein was only 0.192 6 mg/L and also far below to 0.845 7 mg/L of the normal alga protein expression without the inhibition of algicidal bacteria R1. FTIR results showed algicidal bacteria R1 could influence scenedesmus cell structure. The obvious inhibition of algicidal bacteria R1 on scenedesmus was also proved through phase contrast microscope during their co-culture process. [Conclusion] The inhibition mechanism of algicidal bacteria on scenedesmus including scenedesmus cell structure changes, scenedesmus protein and scenedesmus photosynthesis so on have been analyzed.

Abstract:[Objective] The study aims to isolate and identify xylan-degradation bacteria from the gut of a fungus-growing termite——Macrotermes barneyi. [Methods] Using an oligotrophic medium containing birchwood xylan as the only carbon source and Congo red activity staining method, we obtained a xylan-degradation bacteria based on the transparent zone around the clone and the bacteria was identified by microscope morphology, Gram-staining and 16S rRNA gene sequence analysis. To learn the distribution of the xylanase, cell growth curve and xylanase assay of intercellular and extracellular activities were investigated using DNS method. [Results] The xylan-degradation strain, isolated from the gut of M. barneyi, was named as Paenibacillus sp. Mb1. The strain grew to a high level at 72 h. Paenibacillus sp. Mb1 secreted extracellular xylanase at a rapid rate in the exponential phase, and reached to the maximal xylanase production at 96 h, then kept steady until the end of Mb1 cultivation. [Conclusion] Paenibacillus sp. Mb1 with high xylanolytic activity have been isolated from the hindgut of M. barneyi. It might be a good candidate strain in studying termite xylan degradation and biomass conversion.

Abstract:[Objective] Purpose of this work was to research the regulation effect of catabolite control protein A (CcpA) on chitinase gene chiA and chiB in Bacillus thuringiensis subsp. israelensis 75 (Bti75). [Methods] We used the PREDetector software program to analyze the upstream regulatory region of chiA and chiB in Bti75, in addition, specific binding of CcpA protein to the promoter region of chiA and chiB was determined by electrophoretic mobility shift assay (EMSA). In order to acquire ccpA deletion mutant ΔccpA, we constructed a ccpA knockout vector. Then, the influence of CcpA to chiA and chiB in Bti75 strains with and without glucose was detected by quantitative real-time reverse transcription PCR (qRT-PCR) and Western blot. [Results] PREDetector software program analysis showed that there is a potential CcpA binding site crechiB in the promoter region of the chiB, while the similar site is not found in the chiA promoter region. In vitro, CcpA could bind specifically to the chiB promoter with the assist of Hpr-Ser45-P, but the binding of CcpA to chiA promoter is non-specific. The results of qRT-PCR and western blot revealed that ccpA deletion led to a significantly increased expression of chiB, however, the change of chiA expression was not obvious. [Conclusion] The expression of chiB not chiA in Bti75 was negative controlled by CcpA in the presence of glucose.

Abstract:[Objective] To improve the soluble expression level and enzyme activity of CGTase in prokaryotic expression system, the expression conditions were optimized. [Methods] The cgt gene was cloned from Geobacillus sp. B1 and cloned into expression vector pET-28a(+). The optimum induction temperature was selected by enzyme activity assay and SDS-PAGE. The molecular chaperone co-expression system was constructed and the optimum molecular chaperone vector was screened. [Results] The results was described as follows: the cgt gene was amplified and cloned into vector pET-28a(+) successfully, the enzyme activity and soluble expression level of CGTase was highest when induced at 25 °C; in the molecular chaperone co-expression system, the five vectors containing different molecular chaperones (pKJE8, pKJE7, pGro7, pTf16 and pG-Tf2) improved and the enzyme activity and soluble expression level of CGTase in varying degrees when co-expression with recombinant plasmid pET-28a(+)-ompA-cgt, and pKJE8 was confimed to contain the optimum molecular chaperones combination and the enzyme activity of CGTase improved 48.6%. When L-Arabinose concentration of 0.5 g/L, molecular chaperone plasmid pKJE8 made extracellular enzyme activity increased 68.5%. [Conclusion] These results can provide a potential value for further studies of CGTase.

Abstract:[Objective] In order to establish an efficient arbuscular mycorrhiza (AM) fungi propagation system, three AM fungi were selected to test their compatibility with three different host plants and the effects of planting modes on fungal propagation. [Methods] Three selected AM fungi (Acaulospora laevis, Glomus monosporum and G. intraradices) were used to inoculate three crop species, namely maize (Zea may L., C4 broad-leaf plant), sorghum (Sorghum bicolor (L.) Moench, C4 narrow-leaf plant) and white clover (Trifolium repens L., C3 plant). The three crops were planted as intercropping or monocropping modes. [Results] The aboveground biomasses of the host plants and their rhizosphere AM fungi spore density in the intercropping mode of the three crop species were significantly higher than those in monocropping mode, respectively (P<0.05). The aboveground biomass of maize was not significantly affected by the AM fungal species regardless planting modes (P>0.05), while reduced aboveground biomass was observed in sorghum under intercropping mode inoculated with G. monosporum or G. intraradices, respectively (P<0.05). The aboveground biomass of intercropped white clover was significantly improved by the inoculation of G. intraradices (P<0.05). [Conclusion] Our studies suggest that host preference of the three AM fungi and their host plants exists, and the possible so-called “symbiotic complementary functions” between the tested C3 and C4 plants to AM fungi could be used for AM fungi propagation and their potential applications in crop production.

Abstract:[Objective] There is almost no report about the sheep-derived Clostridium butyricum in the world at present. It is the study that optimized of liquid fermentation for sheep-derived Clostridium butyricum HDRyYB1. This study sets the foundation for Clostridium butyricum HDRyYB1 industrial product as feed additive in livestock. [Methods] We used the Plackett-Burman (PB) design and response surface methodology (RSM) though determing the spore number of Clostridium butyricum HDRyYB1 in this report. [Results] The results showed that the concentration of wheat flour, rice flour, fish meal had remarkable effect on the spore number. The optimum medium for incubating the Clostridium butyricum HDRyYB1 was composed of 3.72% wheat flour (w/v), 0.90% fish meal (w/v), 3.96% rice flour (w/v), 0.60% yeast powder (w/v), 0.19% NaCl (w/v), 0.19% MgSO4·7H2O (w/v), 0.01% KH2PO4 (w/v), 0.01% NaHCO3 (w/v), 0.48% CaCO3 (w/v), at 37 °C, pH 7.2?7.4, bottled in 100/250, inoculated quantity 3%. Under this condition, the spore number was 1.478×108 colony-forming units (CFU)/mL after fermented completely in 18 h, which was 2.7 times than before. [Conclusion] These results indicate that the fermentation medium has been optimized, it can be used in the expanded fermentation experiment to verify its application value in production practice.

Abstract:[Objective] To investigate the effect of physical and chemical properties on the diversity of bacteria of Tricholoma matsutake shiroes. [Methods] Soil from Tricholoma matsutake shiroes and control treatments were collected at the T. matsutake’s harvest time in the main producing areas Xiaojin, Yajiang, Muli, Yanyuan, and Yanbian in Sichuan denaturing gradient gel electrophoresis (DGGE) was used to analyze the bacterial diversity in shiroes. Physical and chemical properties of soil samples were analyzed. Data analysis was done using principal component analysis (PCA) and multiple regression tree analysis (MRT). [Results] The physical and chemical properties of shiro soils were significantly different. The fertility level was significantly higher in shiro soils than in control treatments. The diversity indices in different counties were significantly different. However, bacterial diversity in the control soils was not necessarily lower than in shiro soils from the same area. MRT showed that higher organic matter (OM, 136.5 g/kg≤OM≤257.1 g/kg) and higher available nitrogen (AN, 151.2 mg/kg≤AN≤277.0 mg/kg) increased the bacterial diversity of shiro soils when the concentration of available copper (Cu) was higher than or equal to 0.296 7 mg/kg and less than 0.651 7 mg/kg. Whereas, lower pH (4.800

Abstract:[Objective] Solid-state fermentation (SSF) media for growth of the two endophytic fungal strains (YCEF005 and YCEF053) were investigated. [Methods] The composition of fermentation substrates were optimized through single factor experiment and orthogonal experimental design. The additional nutrients and inoculum dose on the basis of the fermentation substrates were optimized through the combination of single factor experiment, uniform experimental design as well as artificial neural network with genetic algorithm. [Results] The optimal fermentation substrates for YCEF005 are as follows (W/W): 50% wheat bran, 10% bean cake powder, 20% rice bran, 20% corn flour. The optimal fermentation substrates for YCEF053 are as follows (W/W): 60% wheat bran, 10% bean cake powder, 10% rice bran, 20% corn flour. The optimal additional nutrients and inoculum dose (per kg substrates) for YCEF005 is as follows: sucrose 12.96 g, peptone 12.70 g, NH4NO3 4.00 g, KH2PO4 1.50 g, CaSO4 10.00 g, MgSO4 0.48 g, water content 500 g, inoculum dose 24 mL. The optimal additional nutrients and inoculum dose (per kg substrates) for YCEF053 is as follows: sucrose 13.37 g, peptone 14.02 g, NaNO3 3.85 g, KH2PO4 1.23 g, CaSO4 10.89 g, MgSO4 0.52 g, water content 480 g, inoculum dose 20 mL. The maximum fungal biomass was achieved when cultured on the optimal medium for 7–9 d. [Conclusion] The biomass of fungal SSF was improved by optimizing the media compositions.

Abstract:[Objective] We evaluated the effects of lactic acid bacteria consortium on sea bass pieces in cooling storage. [Methods] Three lactic acid bacteria were verified to inhibit Pseudomonas fragi and Shewanella putrefacens in sea bass pieces. Then we formulated a consortium based on the verified lactic acid bacteria to treat the fish before cooling. The changes of sensory analysis, total volatile base nitrogen (TVB-N values) and specific spoilage organism count indices during cooling at 4 °C were measured. [Results] The inhibitory effects of single Lactobacillus casei LC1, Lactobacillus plantarum LP1 and lactic acid bacteria L3 on Pseudomonas fragi and Shewanella putrefacens were observed. The consortium, composed of Lactobacillus casei LC1, Lactobacillus plantarum LP1 and lactic acid bacteria L3, significantly inhibited specific spoilage organism, Pseudomonas fragi and Shewanella putrefacens. During the cooling storage of sea bass pieces treated with the consortium, the changes of sensory and TVB-N values were delayed for 6 d and 2 d, respectively. [Conclusion] Lactic acid bacteria consortium could effectively extend the shelf-life of sea bass pieces during cooling storage.

Abstract:[Objective] In order to characterize Streptococcus agalactiae isolates of bovine origin from North China. [Methods] Five hundred and fifty-seven milk samples were collected in 2012?2015 from dairy cows with subclinical mastitis in Inner Mongolia Autonomous Region, Hebei Province and Beijing, and S. agalactiae isolates were identified by biochemical analysis and molecular biological methods. Their drug sensitivities were detected using standard disk difusion method, and the genes for capsular type, surface protein and virulence factors were amplified by PCR. [Results] Twenty-eight streptococcal isolates were ientified as S. agalactiae with a isolation rate of 5.03% and similar drug sensitivities. All of 28 S. agalactiae isolates belonged to capsular type Ia with similar virulence gene patterns and undefined surface protein types. [Conclusion] These data indicate that the S. agalactiae isolates of bovine origin in different regions of North China had similar drug sensitivities and virulence gene patterns, which provided the rationale for development of therapeutic strategy and vaccines against bovine mastitis S. agalactiae.

Abstract:[Objective] Screened positive strains which had PKSⅠ, PKSⅡ and NRPS genes from 19 endophytic antagonism actinomycetes strains of Sophora alopecuroides L. and preliminary identified types of antibiotics produced by them, which could also provide research methods and theory on rational development and use of endophytic actinomycetes from Sophora alopecuroides L. [Methods] Specific amplified 19 endophytic antagonism actinomycetes by primers of PKSⅠ,PKSⅡ and NRPS genes for screening positive strains. Then 7 kinds of antibiotics were used as contrast and preliminary identified antibiotics produced by positive strains which had PKSⅠ, PKSⅡ and NRPS genes by TLC and HPLC methods. [Results] The rates of positive strains of PKSⅠ, PKSⅡ and NRPS genes were 47.4%, 10.5% and 21.1% respectively. The fermentation broth of 9 endophytic actinomycetes had a peak respectively which had the same elution time with medemycin, the fermentation broth of strain NDZKDS69 had four peaks which had the same elution time with medemycin, acetylspiramycin, teicoplanin and oxytetracycline respectively. [Conclusion] Strepomyces of endophytic actinomycetes from Sophora alopecuroides L. were rich sources of macrolide antibiotic, aromatic polyketide antibiotics and non ribosomal peptide antibiotics. The testing results of molecular fingerprinting and chemical fingerprint chromatography were consistent, and the methods of TLC and HPLC were founded in this paper were convenient, rapid, sensitive and had better repeatability.

Abstract:[Objective] We analyzed the evolution and mutations of PB1 genes among seasonal H3N2 influenza viruses, to reveal the molecular characteristics and evolutionary trend of PB1 genes. [Methods] We analyzed PB1 and PB1-F2 genes by molecular biological software with 82 A/H3N2 viruses from 1968 to 2014 in China, 81 viruses isolated from Jiangsu Province between 2012 and 2014, 6 swine influenza viruses and 4 avian influenza viruses. [Results] PB1 segments in China showed high nucleic acid and amino acid sequence similarity (90.91% to 100%, 96.91% to 100%). The phylogenetic tree of PB1 genes was divided into 4 clusters. Strains isolated from 2002 to 2014 located in Clade IV and 1968 to 1994 were in Clade II and III. SIVs dispersed in Clade I, II, IV suggesting a reassortment of PB1genes may occurred in swine population between A/H3N2 and other subtypes. Compared to strains isolated from 1968 to 1994, the amino acid substitution of PB1 gene (52, 113, 179, 216, 576, 586, 619, 621 and 709) was observed between 2002 and 2014 with adaptive changes. Truncated PB1-F2 protein included 52, 34, 25, 24 and 11 aa (SIV). The mutation of the key virulence sites did not appear among Human A/H3N2 influenza. [Conclusion] PB1 segments of A/H3N2 influenza virus underwent stable evolution and mutation, the truncated PB1-F2 protein has become a new trend in its evolutionary process. This finding suggests that we should pay great attention on the reassortment of PB1 genes and its mutation on key virulence sites. This emphasizes the importance of virus surveillance of A/H3N2 virus.

Abstract:[Objective] To investigate the antimicrobial mechanism of DNA action of CecropinA-Magainins treatment on the Methicillin-resistant Staphylococcus aureus (MRSA). [Methods] The mechanism was analyzed by Confocal Laser Scanning Microscope (CLSM), Gel shift Assay, Ultraviolet Spectrum Analysis and Fluorescence Spectrum Analysis. [Results] The results demonstrated that the minimal inhibitory concentration (MIC) of the peptide against MRSA was 64 mg/L. The hybrid peptide could accumulate within the bacterial cell, and bind with the genomic DNA in vitro. Meanwhile, the hybrid peptide caused the change of DNA conformation. The results of Fluorescence Spectrum Analysis showed that the hybrid peptide competitively embedded genomic DNA with EB, and its combination mode was similar to the mode of EB and DNA. Finally, we found the combination mode of hybrid peptide and DNA was mixed mode. [Conclusion] CecropinA-Magainins can enter into the bacterial cell, bind with the genomic DNA. The hybrid peptide kills bacteria via intracellular-targeting mechanism.

Abstract:As inducement causes of food-borne diseases，the common food-borne pathogens are the pathogenic microorganism spreaded by food which usually cause food poisoning. Metabolomics of food-borne pathogen were to study the regularity and characteristic of the pathogenic bacterial small molecule metabolisms, then to look for new detection targets and establish the food-borne pathogen identification technology based on metabolomics method. The analysis of foodborne pathogens volatile metabolites has been proposed as an alternative method for the identification of pathogens in food as the current metabolomics technology matures and existing microbial volatile metabolites database. This paper reviewed the metabolomics of common food-borne pathogen research technology and its research progress in clinical and food detection, simultaneously highlighted its broad application prospect.

Abstract:Over the past decade, due to the addition of new genera and species to this important bacterial group, the classification of rhizobia has been gone through a substantial change. The recent progress of the classification of the rhizobia from the second edition of Bergey’s Manual of Systematic Bacteriology to date was summarized in the paper. Browse our selection of published papers have shown a great diversity among nitrogen-fixing bacteria isolated from different legumes. Currently, about 100 species belonging to 17 genera of α-, β- and γ-Proteobacteria have been described as rhizobia. Class of α-Proteobacteria include the genera Rhizobium, Sinorhizobium, Ensifer, Shinella, Neorhizobium, Pararhizobium, Mesorhizobium, Bradyrhizobium, Phyllobacterium, Methylobacterium, Microvirga, Ocrhobactrum, Azorhizobium and Devosia; Class of β-Proteobacteria include Burkholderia and Cupriavidus (formerly Ralstonia); Class of γ-Proteobacteria include Pseudomonas. There are about 748 genera and 19 700 species of leguminosae plants around the world, and about 172 genera and1 485 species of leguminosae plants in China. Among of the 19 700 species of leguminosae plants, only 23% leguminous plants have been surveyed the ablilty of nodulation. Therefore, it is necessary to survey the different regions of legumes using advanced methods, and we can obtain the new rhizobia resources.

Abstract:listeria monocytogenes infection can cause listeriosis in human and animals. When organisms are infected with L. monocytogenes, pattern recognition receptors such as NLRs and DNA/RNA sensor in cytosol sense bacterial pathogen associated molecular patterns and bacterial virulence factors, and form multiprotein complexes called inflammasomes for immune defense. Recent studies confirm that NLRP3, AIM2, NLRC4, RIG-I and NOD1/2 inflammsomes can sense listeriolysin O, bacterial DNA, flagellin, bacteria RNA and protein peptidoglycan fragments, respectively. Subsequently, these inflammasomes are activated, which regulate the expression, maturity and secretion of proinflammatory factor including interleukin (IL)-1β and IL-18 to cause tissue inflammation, cellular immune response. In addition, activated inflammasomes can induce caspase1-dependent pyroptosis. In this review, the above-mentioned issues were discussed based on the recent research progress.

Abstract:Three Yersinia species are pathogenic to rodent and human, include Yersinia pestis, Y. enterocolitica and Y. pseudotuberculosis. Y. pseudotuberculosis can transport across microfold cell (M cell) distributed on the peyers patch of small intestine of mouse. They initially take advantage of the surface docks such as adhesins YadA or invasin to interact with β1 chain of integrin receptors at the host cell surface. Then, Yops are exported by the type III secretion systems (TTSSs) when secretion channels open, and finally give rise to suppressed host immune response. Many studies about Y. pseudotuberculosis have been published over the past 30 years. Advances about molecular mechanism of interaction between Y. pseudotuberculosis and host cell have been reviewed here. Meanwhile, the focal point and developing trend about Y. pseudotuberculosis were also discussed.

Abstract:Salmonella is an important foodborne pathogenic bacterium, with more than 2 500 serotypes. A number of techniques have been developed for Salmonella subtyping, including phenotypic and genotypic techniques. Traditionally, Salmonella isolates are identified and typed by phenotypic techniques such as serotyping and phage typing. During the last two decades, genotypic techniques have been used for differentiation of Salmonella isolates and source tracing of foodborne outbreaks. These methods include molecular serotyping, pulsed field gel electrophoresis (PFGE), multi-locus sequence typing (MLST), multi-locus variable number of tandem repeats analysis (MLVA), and clustered regularly interspaced short palindromic repeats (CRISPR). Compared with phenotypic methods, genotypic methods are widely applied for Salmonella typing due to their high discriminatory power and good reproducibility. Molecular serotyping, as a new method, is to identify serotypes of Salmonella by PCR. PFGE is considered the “gold standard” for Salmonella subtyping. MLST and MLVA, as DNA sequencing-based methods, are publicly available online and can be compared readily between laboratories. CRISPR typing has a high distinguish capacity among the same serotype with homology and satisfying genotyping result. However, each typing method has different advantages and drawbacks, operating conditions, and applicability. Therefore, it is necessary to choose the suitable typing methods for genetic diversity analysis according to the characteristic of strains and experimental facilities available.

Abstract:The global regulator VeA has only been found in fungi and conserved in numerous fungal species. VeA is involved in the regulation of diverse cellular processes, including development and differentiation, secondary metabolism, oxidative stress response as well as pathogenesis in numerous fungal species. The review presented here summarized the information on the current understanding of VeA function and its mechanism of action in Aspergilli, with the aim of facilitating the construction of anti-infection crops and design of effective strategies for controlling fungal dissemination, survival, pathogenesis to decrease the Aspergilli contamination of agricultural commodities. Both the role of veA gene that needs to be further characterized for future research and the potential target that may be used for controlling mycotoxin contamination were also discussed.

Abstract:Postacidification which is produced by lactic acid bacteria, always occurs in yogurt during the storage, transportation and consumption, leads to milk fermentation with high acidity, and affects the sensory and flavor of yogurt. The mechanism of acid resistance in lactic acid bacteria and postacidification was introduced in this paper. In addition, physical, chemical and biological methods of controlling postacidification were expounded and prospected.

Abstract:Based on the principle that content is the core factor of a course, the problems in both teaching and teaching content reforms were analyzed in developing food microbe detecting abilities of the students in food nutrition and detection major in higher vocational colleges. According to the actual requirements and occupation standards of food industry, the necessity and urgency of the teaching content reform were expounded and what contents should be included in teaching was elaborated. Great importance was attached to the construction of teaching contents regarding food microbe detection in order to enhance students’ abilities to detect microbes in food. In teaching practice, the comprehensively constructed teaching contents could attain above training objective.

Abstract:[Objective] This study aimed to establish the cryopreservation technique of Spirulina that with low temperature tolerance and research the preservative applicability of this method to the different Spirulina. [Methods] We screened out the low temperature tolerant Spirulina by iodometric method. This paper used the single factor analysis and orthogonal experimental designed method to optimize the conditions to the cryopreservation technique of Spirulina with low temperature tolerance, and then used this optimized method to preserve the eight different kinds of Spirulina. [Results] The result showed that the FACHB-351 Spirulina was the best one to endure the low temperature, and the optimal cryopreservation conditions were obtained as follows: using the 10% sucrose solution as the cryoprotectant, putting the algal cell density of 1.0×107 CFU/mL in the 4 °C refrigerator liquid and cultivating for 72 h, mixing up the algae fluid and protective agent after precooling at 0 °C for 30 minutes respectively, and then preserving it in the liquid nitrogen after the mixture liquid stayed at 0 °C for 3 h. This experimental result indicated that FACHB-350, FACHB-1070, FACHB-902 were no-resistant to low temperature and lost cell activity with the survival rate of 0% after preservation for six months, the rest five kinds of Spirulina could resurrect during a certain period of time for the growth of normal. And the FACHB-351 showed be the highest survival rate 39.33%. [Conclusion] This study established the cryopreservation method which was suitable for the preservation of good low temperature resistance Spirulina.

Abstract:[Objective] The research aimed to establish a rapid, sensitive and specific method for detection of staphylococcal enterotoxin A (SEA). [Methods] The soluble protein His-tagged SEA expressed in Escherichia coli was used as the immunogen to produce specific antibodies with high affinity. A double antibody sandwich ELISA (DAS-ELISA) was developed using anti-SEA monoclonal and polyclonal antibodies as capture antibody and detection antibody respectively. [Results] There was good linearity in the toxin range of 2?128 μg/L (y=1.102x-0.07, R2=0.994) with the detection limit at 1.89 μg/L. The assay showed no cross-reactivity with SEB, SEC2 or SED. The average recovery rates for SEA in milk ranged from 94%?114% with the variation coefficient less than 10%. In addition, the method was also successfully used to detect SEA-producing strains in culture filtrates. Of 46 Staphylococcus aureus isolates from aquatic products, 4.4% were SEA-producing, while 50.6% for 164 bovine mastitis isolates. [Conclusion] Therefore, the DAS-ELISA method was sensitive and specific, and could be used as a mean for monitoring food-borne SEA contamination.

Abstract:[Objective] To optimize the experiment protocol of ultraviolet (UV) radiation of Bacillus subtilis so that students can get better results in the experiment lesson. [Methods] We optimized the protocol by determining the best bacterial cultivation, estimation of viable cells, and UV-radiation parameters. [Results] Liquid medium was better than agar slant to obtain a homogeneous suspension of cells. The cell amount of the initial bacterial suspension was estimated efficiently by turbidimetric method, which was convenient to dilute the initial suspension to a concentration of 102?103 CFU/mL. Dry surface covered with dry dish was necessary for the formation of singlet colonies on a bacteria-inoculated plate. During UV exposure, the lethal effect was affected by the adding volume of suspension and mixing speed. [Conclusion] The optimized protocol produces repeatable results easily and can be used for teaching or research.