Abstract:

Abstract:

Abstract:[Objective] Quorum sensing inhibitory activity of some marine bacterial isolates was investigated to provide potential novel origins of natural products for the promising anti-bacterial therapeutic approaches targeting on the quorum sensing system of some pathogens. [Methods] In this study, we used Chromobacterium violaceum as the report-strain to screen for the quorum sensing inhibitory activity from some marine bacterial isolates by disc diffu-sion assay and double-layer soft agar assay. [Results] In total, 272 bacteria strains isolated from the sponge tissues collected around the San Juan Island had been tested. The results showed that 51 isolates exhibited the quorum sensing inhibitory activity. Among the active strains, bacterium No.74 had the strongest activity, which is deserved the further study on the isolation and identification of quorum sensing inhibitors. [Conclusion] Many marine bacterial isolates exhibit quorum sensing inhibitory, which indicated that marine bacteria are also a po-tential source for the natural quorum sensing inhibitors.

Abstract:[Objective] In this paper, the effects of organic solvent stresses on the yield of antioxidant exopolysaccharide (EPS) from Bacillus subtilis was evaluated and the best condition was also determined. [Methods] Marine strain Bacillus subtilis OST23a and mutant UM29, both with the ability to produce antioxidant exopolysaccharide (EPS), were used as the original strain. Based on the detection of the tolerance of the strains to the organic solvent, n-hexane was used to stress treatment. Effects of concentrations and treatment time of n-hexane on the exopolysaccharide excretion from Bacillus subtilis OST23a and strain UD292 were studied. [Results] The productivity of the EPS of Bacillus subtilis OST23a and strain UD292 were 52.97 mg/L and 201.81 mg/L respectively after stress treatment with 3% n-hexane for 6 h. There was no significant difference in the antioxidation activities of the extracellular polysac-charides between strains stress with n-hexane and the original strains. Moreover, the continu-ous passage experiment showed that the strains have high genetic stability. [Conclusion] The organic solvent stress could improve the productivity of the exopolysaccharide from bacteria, which possesses the potential application in microbial breeding.

Abstract:[Objective] To isolate, protect thermophilic microbial resources from petroleum reservoirs and analyze these main metabolic characterization. [Methods] The strain BF1 was isolated by Hungte anaerobic technique from Chenghai 1 Unit of Dagang oil field in China. Its taxonomic status determined by physiological, biochemical and 16S rRNA gene sequence analysis. Its effect of sulfur metabolism on the corrosion current was measured by electrochemical analysis. [Results] The strain BF1 was Gram-negative, strictly thermophilic anaerobic, top-sporulating, non-motile, rods, 0.42 μm×(1.6?5.4) μm, grew solitary, in pairs or in chains. Growth occurred at 45 °C?75 °C (optimum 60 °C), at pH 4.5?8.5 (optimum 6.5). Specific growth rate (μm) was 0.99 h?1 and doubling time was 42 min. Substrates included glucose, melizitose, raffinose, mannose, lactose, fructose and ribose. The main products of glucose fermentation were CO2, H2, acetate and ethanol. The strain could reduce thiosulfate and sulfite to sulfide, and its tolerance limits were 75 mmol/L and 50 mmol/L, respectively. The electrochemical impedance reduced from 2 099 Ω/cm2 to 776 Ω/cm2 and the corrosion current increased from 9.936e-006 A to 3.25e-005 A after thiosulfate (50 mmol/L) was reduced. The fatty acids were mainly composed of saturated long chain fatty acids, with C15:0 the most, accounting for 70.6%. The G+C content of DNA was 34.0 mol%. The 16S rRNA gene sequence analysis indicated that the closest phylogenetic relatives were Thermoanaerobacter pseudethanolicus DSM2355T and T. brockii subsp. brockii DSM1457T, 98.3% and 98.0%, respectively. However, the strain BF1 was different with T. pseudethanolicus DSM2355T and T. brockii subsp. brockii DSM1457T in doubling time, optimum temperature and substrates utilized, and different with T. pseudethanolicus DSM 2355T in fatty acid profile. [Conclusion] The strain BF1 may be a new species of Thermoanaerobacter genus, the exact taxonomic status of it requires DNA hybridization further. The corrosion current density improved by its metabolic element sulfur may cause corrosion of oil pipelines and equipments.

Abstract:[Objective] To investigate geographical distribution of Acanthus ilicifolius endophytic actinomycetes of different mangrove regions, and their environmental adaptation. [Methods] Endophytic actinomycete strains were isolated from different part of Acanthus ilicifolius plant collected from 5 mangrove sites using 9 different selective isolation media. Isolates were identificated to genus level using 16S rRNA gene sequence analysis. NaCl tolerance was tested using ISP 2 liquid medium supplement with different NaCl concentrations. Potential of nitrogen-fixation isolates were surveyed using nitrogen-free medium. [Results] A total of 52 endophytic actinomycete strains were successfully isolated from Acanthus ilicifolius plant, among which 5 isolates were from surface- sterilized leaves, 2 isolates from stems and the re-maining 45 isolates were from roots. Analysis of 16S rRNA gene sequences of these isolates showed that they belonged to members of the genera Jishengella (1 isolate), Micromonospora (47 isolates), Streptomycetes (3 isolates) and Verrucosispora (1 isolate). Forty eight isolates were halo-tolerant or halophilic, including 18 isolates exhibited highest tolerance come up to 20% NaCl, 4 isolates can’t grow in salt-free medium, and 12 isolates exhibited good growth in presence of 3.3% NaCl. Meanwhile, 4 strains can grow on nitrogen-free medium that showed potential of nitrogen-fixation. [Conclusion] Analysis of 47 Micromonospora isolates from 5 mangrove locations indicated that there were different endophytic Micromonospora groups of Acanthus ilicifolius among different geographical sites. The results obtained revealed the en-vironmental adaptation of the Acanthus ilicifolius endophytic actinomycetes.

Abstract:[Objective] Both Beauveria bassiana and Verticillium lecanii are insecticide fungus for biological pest control in the using of study at home and abroad. In order to extend the scope and strengthen the effect of prevention and reduce the cost of biological pest control. co-fermentation have been applied in this investigation. [Methods] The feasibility of co-fermentation have been studied through comparing sporulation capacity, indoor antibiotic activities of two mixed strains. [Results] Results showed that the best ratio at 1:1 of Verticil-lium lecanii L-31 and Beauveria bassiana Q-55 by co-fermentation. Taked 10% from every inocu-lated in fermentation medium (Fermentation medium were prepared by yeast extract 5.0 g/L, glu-cose 20.0 g/L, malt extract 5.0 g/L, KH2PO4 3.0 g/L, millet 200.0 g/L, pH 6.5), 23.0 °C±0.1 °C fermentation temperature 12 d standed the total of spore-containing fermentation broth could reached 1 × 109 CFU/mL or more and have the stronger insecticide toxicity. It had inhibited effect on both Trialeurodes vaporariorum and Pieris rapae L. 9 d after treatment of the lethal concentration LC50 were 2.09×104±0.12 CFU/mL and 3.17×105±0.11 CFU/mL, broth con-centration 1×108 CFU/mL at the time of death in the LT50 was 2.11±0.14 d and 4.27±0.43 d, correct anti-greenhouse effect in the plot experiment more than 80%, having significant dif-ference with the single strain fermentation control effect. [Conclusion] It provides a scientific basis for further application of the two insecticidal funguses and a reference efficiency way for Spread-spectrum anti-fungal for spread spectrum efficiency of fungal biocontrol agents.

Abstract:[Objective] Two thermophilic fungal species which were isolated from the compost of cotton residue in Xinjiang were identified, and increased degradation rate of straw by optimizing the impact factors for cellulase production. [Methods] Two thermophilic fungal species were identified by morphological observation and analyzed the clone of the ITS gene fragment, The filter paper enzyme activity (FPA) of fungi was determined when they grown in a series of liquid state media containing pretreated natural cellulose as the carbon source, different nitrogen source, different initial pH, different inoculated amount and culture time, by analyzing the change of the FPA. [Results] Z1 is Aspergillus fumigatus Fresen and Z2 belongs to Myceliophthora Cost. (homology 97%). The filter paper enzyme activity (FPA) of fungi was determined when they grown in a series of liquid state media containing pretreated natural cellulose as the carbon source, different nitrogen source, different initial pH, different inocu-lated amount and culture time, by analyzing the change of the FPA, we had got the optimal conditions of fermentation. Under the optimal conditions, the decomposing (cotton residue) rate of Z1 was 10.19% and MS was 53.45% for 10 days, the decomposing (wheat straw) rate of Z2 was 27.50% for 10 days. [Conclusion] Degradation rate of straw MS better than single strains was more than half. It has great potential in recycling natural cellulose of Xinjiang when applied the fungal, which can degrade not only cotton residue but also wheat and rice straw, it has great potential for further apply in straw degradation.

Abstract:[Objective] The expression, purification of quinolinic acid phosphoribosyl transferase (QPRT) and nicotinic acid phosphoribosyl transferase (NaPPT) from Escherichia coli (E. coli) were undertaken in prokaryotic expression system and activity detection of QPRT and NaPPT in vitro. [Methods] The NadC encoding QPRT and PncB encoding NaPPT were cloned and then ligated into pET28a and pRSETB to generate the expression plasmid pET28a-NadC and pRSETB-PncB, respectively. The plasmids were expressed in E. coli BL21(DE3) and enzymes were purified in vitro. Enzymes activity were detected by analyzing the reaction mixture on a high performance liquid chromatography (HPLC) system. [Results] QPRT and NaPPT were expressed and purified, the results indicate that quinolinic acid can be transformed into nicotinic acid through regioselective decarboxylation catalyzed by recombinant QPRT and NaPPT sequentially.

Abstract:[Objective] In order to extract the functional components from Lentinula edodes efficiently for the further utilization of its edible value. [Methods] Using Lentinula edodes as raw materials, the hydrolysis process conditions by composite enzyme including cellulose, papain and 5'-phosphodiester-ase were studied on the basis of single factor experiment and orthgonal test. [Results] Firstly, it was hydrolyzed by 0.2% cellulose and 0.4% papain. The conditions were 55 °C, initial pH 5.5 and 3 h. Secondly, it was hydrolyzed by 0.2% 5'-phosphodiesterase. And the conditions were 70 °C, initial pH 7.0 and 2 h. Under these conditions, the hydrolysis degree was 39.48%, and the extracting rate of amino acids, 5'-nucleotide, polysaccharide were 10.25%, 0.768%, 8.67% respectively. [Conclusion] The hydrolysate was rich in umami substances and other nutrients, and it could be used for condiment.

Abstract:[Objective] The function of the uncharacterized gene Afu4g13170 in Aspergillus fumigatus was ascertained. [Methods] Double-joint PCR method and one-step gene deletion technique were used to generate the A. fumigatus ΔAfu4g13170 mutant. [Results] Amino acid sequence alignment shows that the predicated Afu4g13170 protein has a similarity of 88.6% to Gib2 protein in Cryptococcus neoformans and Ani04163 protein in A. nidulans. The phenotypic analysis indicated that deletion of Afu4g13170 gene results in growth defect and incomplete development of phialides with elongated metulae, delayed and reduced sporulation, and less pigment production. Chromatographic analysis suggested that gliotoxin production is blocked partly by knocking out the Afu4g13170 gene. [Conclusion] Afu4g13170 gene may be used as one of target sites to control the virulence of A. fumigatus.

Abstract:[Objective] To investigate the immunoprotection of pilus subunit SSU2100 which was encoded by srtBCD pilus island presented in the Chinese strain 05ZYH33 of S. suis 2. [Methods] The SSU2100 gene was amplified by PCR, then cloned into prokaryotic expression plasmid pET28a, and expressed the recombinant SSU2100 in E. coli BL21. The SSU2100 protein was purified by affinity chromatography and analyzed by Western blotting. The mice anti-SSU2100 serum was prepared by immunizing mice with recombinant SSU2100 protein and analyzed by ELISA. [Results] The high titer of the serum were obtained, Western blot result indicated that the recombinant protein can react with mice anti-SSU2100 serum. Animal test showed that vaccinating mice with recombinant SSU2100 protein conferred a significant protection. [Conclusion] SSU2100 could serve as a vaccine candidate of S. suis 2, it provides the foundation for system-atically illustrating the role that srtBCD pilus island plays in pathogenicity of S. suis 2.

Abstract:[Objective] To study the role of NODs signaling pathway against the stimulate of Aspergillus fumigatus in RAW264.7 cells by using siRNA to silence NOD2 gene. [Methods] RAW 264.7 cells were inoculated in six-well plate, and then divided into four groups: normal control group (N), normal control group with NOD2 gene silence group, normal with Aspergillus fumigatus spores stimulation group (N+Af) and normal with Aspergillus fumigatus spores stimulation with NOD2 gene silence group. Each groups has three duplicate wells. The expressions of NOD1、NOD2 and RIP2 mRNA in each group were studied by RT-PCR and the expression of TNF-α in each group was detected by western blot assay. [Results] Compared with the N group, expressions of NOD1、NOD2 mRNA and TNF-α protein increased significantly in N+Af group; Compared with negative control group, the expression of NOD2 mRNA was sig-nificantly suppressed in NOD2(RNAi) group, the silencing effect was reached to 80%, indicating that NOD2 gene in RAW264.7 cells was succsessfully silenced. Compared with NOD2(RNAi) group, the expressions of NOD1、NOD2 mRNA and TNF-α protein were slightly increased, but no siginifcant difference (P>0.05). Compared with N group, the ex-pression of TNF-α protein was increased significantly in NOD2(RNAi) group; Compared with N+Af group, the expression of TNF-α protein was lowered significantly in NOD2(RNAi)+ Af group. The expressions of NOD1、RIP2 mRNA in each group were changed slightly. [Conclusion] NODs and its signaling pathway play a role in resistance to Aspergillus fumiga-tus in RAW264.7 cells, particularly the role of NOD2 more prominent.

Abstract:The complex interactions between pathogen and the host cause humans' or animals' diseases. The interactions can result in different levels of the host's damage in the cells, tissues and organs. On the one hand, the pathogenicity and virulence of pathogenic bacteria are depended on the pathogen; on the other hand, they are associated with host factors and the interactions between pathogen and the host. Combining Streptococcus suis, in the aspects of adhesion and colonization, invasion, evasion and spread, bacterial strategies for overcoming the defense of host cells were summaried.

Abstract:Potyvirus belonging to family Potyviridae, is the largest plant virus family, which can be responsible for severe economic losses to agriculture world-wide. P3 protein of potyviruses show relatively low homology in compared to other proteins among potyviruses and multi-functional, related with virus replication, infection, resistance and cell-to-cell movement. P3-PiPo, the newly found SMV-encoded protein, is an overlap protein produced via ribosomal frameshifting or transcriptional slippage at a highly conserved within the P3 cistron and play a key role in viral cell-to-cell movement. The functional characterization of potyvirus-encoded proteins supported the understanding of potyviruses, and promoted the research of potyviruses infectious and resistant mechanisms.

Abstract:According to the practice and perception of teaching on courses of laboratory bio-safety to medical students of different degrees, the ideology of teaching, curriculum settings and evaluation methods were summarized. Meanwhile, the main problems encountered in the process of teaching were analyzed. And we hope to improve the consciousness of laboratory bio-safety and quality of medical students through teaching activity.

Abstract:According to the college, students’ learning situation and the characteristics of curriculum, this paper discusses the influence of research-oriented teaching mode for food microbiology teaching. In the process of teaching reform, it emphasizes the students’ innovation ability and comprehensive quality training. It pays attention to the coordination of the theory teaching, experimental teaching and scientific research activities. At the same time it strengthens the process management. Teaching practice shows that the research-oriented teaching mode changes students learning way, and improve the scientific research ability and teaching quality obviously.

Abstract:In order to cultivate the students’ professional ability, and interconnect with positions, this course stresses on skills, focus on job tasks as its teaching content, and is based on proffessional competency to revolutionalize its teaching methods with production procedures as the carrier to design teaching process and processing evaluation as its teaching tools. It has been proved that the revolution of this course is helpful to cultivate the students’ practical skills and their creativities, and to promote vocational education with professional ability as its core task.

Abstract:Enzyme engineering course mainly concerning about enzyme production and application is one of the major courses of biological engineering major. In order to improve teaching effects, the methods of giving lecture on Enzyme Engineering were discussed based on the practice of our college. During the course, a teacher should select the most suitable book, optimize teaching contents, reform teaching methods and teaching means and consummate the examination form.

Abstract:[Objective] To establish a simple method to screen oleaginous yeast and determine the intracellular lipid content. [Methods] The study is based on the theory that the combination of nile red and intracellular oil will emit fluorescence when induced by UV light and the fluoresence indensity is associated with the lipid content. We cultivate yeast in the culture medium added with nile red, and screen the oleaginous yeast strains from the 385 deep-sea yeasts by measns of obeserving the fluorescence of the yeast colony. We have identified the screened oleaginous yeast strains by the 26S rDNA D1/D2 series analysis method. Designating one of the oleaginous yeasts (2A00015) as the test strain, the lipid content rapid determination method by nile red dyeing was established. [Results] 22 oleaginous yeasts were obtained with the lipid content reaching up to 62.9%. Based on the molecular identification, it showed that the 22 yeasts are separately belong to Candida viswanathii, Candida parapailosis, Rhodotorla mucilaginosa, Debaryomyces hansenii, Pichia guilliermondii and Rhodosporidium paludi-genum. The optimum condition for lipid content determination by nile red dyeing is: bacterium suspension OD600 lower than 1.2, nile red concentration 0.5 mg/L, dyeing time 5 min, excit-ing wavelength 488 nm, emission wavelength 570 nm. The relative fluorescence intensity ob-tained by this method exhibits a positive association with the lipid content obtained by weigh-ing method, which can be explained as R2=0.9637.