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Abstract:Variation of rhizosphere and non-rhizosphere cultured soil microbes at the different growth stages of Fritillaria pallidiflora were analysed. The correlation of rhizosphere soil microbes with imperialine content were discussed. The results showed that the ecological distribution characteristics of rhizosphere and non-rhizosphere soil microbes at every growth stages (Re-greening stage, bud stage, full flowering stage and harvest-time) of Fritillaria pallidiflora were all bacteria > actinomycete > fungi. Only in bud stage, non-rhizosphere fungi number is more than rhizosphere’s. At other stages rhizosphere bacteria, actinomycete and fungi were more than non-rhizosphere’s. Especially, for bacteria, the rhizosphere effect of Fritillaria pallidiflora was obvious. Number of bacteria and fungi in the rhizosphere soil of full flowering stage are most in all stages. Soil fungi number had extremely marked positive correlation with imperialine content.

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Abstract:This paper studied on the growth, fermentation characteristics and ethanol tolerance of the strain identified as Thermoanaerobacterium saccharolyticum. The result showed that mannose, glucose and xylose were preferable to other carbon sources for its growth, while xylan and cassava starch could be consumed by the strain. Optimum concentration of substrate was 15 g/L. The ratio of glucose: xylose did not show significant influence on the growth. The highest tolerance on ethanol was 3% (V/V). Cultured on the medium of 5 g/L xylan, xylose and cassava starch for 60 h separately, lactic acid, ethanol and acetic acid were detected, and the ethanol concentration was 0.824, 0.867, 0.916 g/L, respectively.

Abstract:Psychrophiles and Psychrotolerants are important resources of biologically active substances and cold-adapted enzymes. A total of 33 cold-adapted strains, including 6 Gram-positive strains and 27 Gram-negative strains, were isolated from soil samples. The analysis of these membrane fatty acids showed that the branched chain fatty acids were the major lipid pattern in Gram-positive bacteria, which may indicates their main cold adapted mechanism. However, the membrane fatty acids of Gram-negative bacteria were various, including unsaturated, branched and short-chain fatty acid. Species identifications were committed for 17 strains with typical fatty acid compositions. They were distributed in 11 genus. Variation of cell membrane lipid composition was consistent with the result of 16S rRNA. In addition, the Gram-negative bacteria exhibited the different strategies on cold adaptation, even that these strains mainly contained the unsaturated fatty acid. Related researches would not only represent cold adapted mechanism of cold-adapted microorganisms, but also provide the precious resources for the utilization of cold-adapted enzymes.

Abstract:In the paper, we took the typical steppe in the west of Keshiketeng County in Inner Mongolia as the sample. We studied the seasonal changes of the quantity of soil microorganisms, soil microbial biomass of microorganism and the soil respiration intensity in light grazing district (LG), moderate grazing district (MG) and heavy grazing district (HG). We also observed the impact on these changes of different grazing intensity. The results show that the quantity of micro-organisms, the soil microbial biomass of microorganism and the soil respiration intensity are obviously changed with season, their highest values all appear in the August. There is obvious correlation between the three; light and middle grazing were beneficial to soil microorganisms, soil microbial biomass of microorganism increased, but heavy grazing have resulted in the quantity of soil micro-organisms and soil microbial biomass of microorganism reduction.

Abstract:Improved NA medium was used to study the diversity of endophytic spore-forming bacteria of Cinnamomum camphora (Linn.) Presl. After spore staining and removing of the redundant isolates, 40 non-redundant spore-forming bacterial isolates were ascertained, which accounted for 29.9% of all the endophytic bacterial isolates, and 25 strains of the 40 were from roots, 5 strains from stems, 10 strains from leaves. Phylogenetic analysis based on 16S rRNA sequences showed that the 40 strains attributed to 12 species of the genera Bacillus, Lysinibacillus, Paenibacillus and Brevibacillus; 7 strains with under 97% sequence similarities respectively to their closely related member were presumed to be potential novel species. Furthermore, microflora of endophytic spore-forming bacteria in roots, stems and leaves of C. camphora showed that some bacteria distributed in different organs, others were organ-specific.

Abstract:DNA-based molecular biology techniques have widely been used as a powerful tool to understand the microbial community. In this paper, a new method to extract microbial genomic DNA from wetland soil was established, namely Calcium Chloride-SDS-Enzymatic. Calcium chloride rather than EDTA chelating agent was used to remove humic acids in the process of direct DNA extraction. The extracting time is less than 4 hours. In comparing with other two methods, this method is more efficient in removing humic acids from wetland soil, and the purity of extracted DNA is higher which can be applied to PCR amplification. It provides an efficient technology to extract and purify microbial genome DNA from soil for microbial ecological studies.

Abstract:The diversity of aerobic anoxygenic phototrophic bacteria (AAPB) has been well examined in marine habitats, but that in eutrophic lake are little known. Gene pufM is related to biosynthesis of photosynthetic reaction center and is widely used in diversity analysis of AAPB. This study constructed and analyzed pufM gene library, to reveal the distribution and phylogenetic diversity of AAPB and discuss their role of AAPB in eutrophic zone of Lake Ulansuhai. 52 clones of the library were obtained, analyzed and clustered into 28 operational taxonomic units (OTUs). Coverage analysis showed that the library coverage value was of 71.4%, which indicated that the clone library could provide a fine inventory of AAPB diversity in the lake. Phylogenetic and statistical analysis of clone library revealed a higher AAPB diversity in the lake, which has a sharp contrast with lower total bacteria diversity of the same lake according to our previous study. Sequences obtained in this study belonged to seven subgroups, namely γ-Proteobacteria (44.2%, including Group-1, -2 and -3), β-Proteobacteria (21.2%), Rhodobacter-like (7.69%) and unknown Group-1 (21.2%) and Group-2 (5.77%). Higher proportion of γ-Proteobacteria in lower salinity lake like Ulansuhai, has not been reported before. Some unique AAPB ecotypes were probably related to eutrophic lake habitat. This suggested that AAPB play an important role in maintenance and stability of eutrophic lake ecosystems.

Abstract:The ptsHIcrr operon of phosphoenolpyruvate: sugar phosphotransferase system (PTS) of Escherichia coli DH5α was deleted to generate DH5α△ptsHIcrr strain, and its characteristics of growth and metabolism were compared with that of DH5α△ptsG. DH5α△ptsHIcrr and DH5α△ptsG were successfully constructed by using a one-step markerless deletion method that is a modified Red homologous recombination combined with specific cutting of I-SceⅠ. In LB medium, DH5α△ptsHIcrr has a significant different characteristic of growth with DH5α and DH5α△ptsG, and the maximum biomass of DH5α△ptsHIcrr is about two times of that of DH5α or DH5α△ptsG. However, there was no difference between the growth of DH5α and that of DH5α△ptsG. In LB medium supplemented with 1% glucose, DH5α△ptsHIcrr and DH5α△ptsG both grew better than DH5α, and the maximal cell densities were approximately 2 times and 2.8 times of that of DH5α respectively. In the end of culture, the concentrations of acetic acid of DH5α△ptsHIcrr, DH5α△ptsG were12.2%, 47% of that of DH5α. In a modified M9 medium, the specific growth rate (1/h) and the specific glucose consumption rate [g/(g·h)] of DH5α△ptsHIcrr were much slower than that of DH5α and a little slower than that of DH5α△ptsG. Altogether, the ptsHIcrr operon-deleted mutant changed the specific glucose consumption rate and showed many different characteristics of growth and metabolism from that of the △ptsG-deleted mutant.

Abstract:The novel lectin was isolated from the mycelium of Hypoxylon sp. by phosphoric acid buffer, precipitation of 20%-70% (NH4)2SO4, DEAE-Cellulose and Sephadex G-100 chromatography. It turned out to be a single band in PAGE. SDS-PAGE showed the subunit of Hypoxylon sp. lectin (HSL) was 15.9 kD. HSL was glycoprotein through dyed by Periodic acid-Schiff reaction, and the carbohydrate content was 15.5%. β-Elimination revealed the bond between the polysaccharide and the protein of HSL was O-type glucopeptide one. The HSL could agglutinate erythocytes regardless of blood type or animal species. HSL was less thermostable, and the hemagglutinating activity declined obviously after being heated 10 min under 50°C. The HSL was alkali-stable but not acid-stable. Its activity was affected by Al3+, Fe3+, Ca2+ and Zn2+. The hemagglutination of the lectin on mouse erythrocytes was inhibited by galactose and lactose among the sugars tested.

Abstract:A Bacillus sp. strain P-25 was isolated from soil nearby the henhouse of Institute of Animal Sciences, Chinese Academy of Agricultural Sciences. This bacterium was identified as Bacillus cereus by analyses of its morphological and biochemical properties and 16S rRNA sequence.

Abstract:L-7, a bacterium which was able to degrade chlorimuron-ethyl, was isolated from the soil of long term applied with chlorimuron-ethyl by enrichment culture. Base on physiological and biochemical characteristics and 16S rRNA sequence analysis, the strain L-7 was identified preliminarily as Stenotrophomonas sp.. The effect of initial concentration of chlorimuron-ethyl, inoculation amount, temperature and pH on degradation efficiencies was studied. The optimal degrading conditions were: initial concentration of chlorimuron-ethyl 100 mg/L, inoculation amount of 5%, pH 4.0, respectively, under the optimal conditions, the degrading efficiency could reach more than 80% after 5 days at 30°C.

Abstract:Identification and typing of Cronobacter spp. was performed by matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI-TOF-MS). Protein mass spectrometric profiles obtained from reference strains and isolates of Cronobacter spp. and Enterobacter cloacae, Enterobacter aerogenes were compared and analyzed, characteristic peak at about 5740 (m/z) was selected as biomarker for identification of Cronobacter spp., 27 of 28 isolated strains could be identified by this marker. Cluster analysis of whole protein mass spectrometric profiles of 32 Cronobacter spp. strains shown that Cronobacter spp. could be divided into 6 different types. MALDI-TOF MS can be used as a new technology for identification as well as typing of Cronobacter spp. based on the protein mass spectrometric profiles.

Abstract:Based on the principle of homologous recombination, we construct gene knock-out mutant of the pilus backbone gene in Streptococcus suis serotype 2 virulent strain 05ZYH33. PCR analysis, Southern hybridization and RT-PCR analysis showed that the target gene was replaced by SpcR cassette. Analysis of biological characteristics showed that there were no differences in mycelial morphology, hemolytic activity and dyeing properties between the mutant and the wild type strain 05ZYH33. Virulence assays with murine model confirmed that the mutant is significantly less virulent than the wild type strain. The results suggest pili plays an important role in the pathogenesis, which laid the foundation for the study of the mechanisms of pilus assembly and biological function in the S. suis serotype 2.

Abstract:An antimicrobial actinomycete, labelled Y-71, was selected from the putrilage soil collected from Yunnan, China. We identified it Streptomyces exfoliatus, by light microscope and SEM observation, physiological and biochemical characterization, cellwall components analysis and 16S rRNA sequence alignment. Its fermentation liquor had wide antimicrobial spectrum, effectively against the Gram-positive and Gram-negative bacteria. The antimicrobial substance was sensitive to high temperature and the 70°C condition could deprive its antimicrobial activity thoroughly. However, it was rather stable under the 2-8 pH value, and couldn’t be degraded by proteases. Based on these results, we proposed that its antimicrobial substances may not be proteins or peptides. Our research revealed the basic features of strain Y-71 and may help a lot to its further study and application, such as the isolation and purification of antibiotics.

Abstract:To evaluate the virulence roles of vjbR, the mutant and complementary strains of vjbR were constructed, and their survival capabilities in macrophage and mice were assayed. By using homologous recombination, the vjbR (BMEII1116) was replaced by kanamycin gene, resulting the deletion mutant 16MΔvjbR. The ORF was PCR amplified and cloned into pMD-18T, which was transformed into mutant strain to generate the complementary strain 16MΔvjbR-C. The three strains, 16M, 16MΔvjbR and 16MΔvjbR-C, were used to infect macrophage and mice, and their survival capability were assayed and compared. The vjbR mutant strain16MΔvjbR showed reduced survival in macrophage and mice, indicating that vjbR is a virulence gene of Brucella, and is essential for establishment of choronic infection.

Abstract:Aspergillus sp. YN1, with cellulase activity, was screened from sheep and cattles feces compost. Different conditions for liquid fermentation which including carbon source, nitrogen source, temperature, pH, capacity of oxygen and inoculum age for the production of cellulases had been studied. The CMCase activity was 0.53 U/mL and the Filter-Paper activity was 0.15 U/mL when YN1 was cultured in the optimized condition for 3 d. In the study of characteristics of cellulases, the optimal reaction temperature was at 70°C and the optimal reaction pH was at 4.0 (in a 30-min reaction period). The cellulase activity retained above 80% when the celluases were treated under the conditions that the temperature was from 30°C to 50°C for 1 h or the pH from 3.0 to 4.0 for 2 h, which showed the celluases produced by YN1 have resistance to heat and acid.

Abstract:We isolated 640 isolates from sunflower rhizosphere. Eighteen antagonistic bacteria screening have against Sclerotinia sclerotiorum. Isolate XRK5 has obviously and steady antibiosis against the pathogenic fungus, and it implys that XRK5 has good application potentiality. Based on the results of morphological characteristics, physiological and biochemical properties and phylogenetic analysis of 16S rRNA, XRK5 was identified as Lysobacter capsici. The sequence of 16S rRNA obtained in this study has been submitted to GenBank and the accession number is FJ959348.

Abstract:A filamentous fungus F02Z2172 which is able to produce ophiobolins was isolated from Wuyishan Nature Reserve in Fujian province. The strain was identified as Aspergillus pseudodeflectus by cultural and morphological characteristics and phylogenetic analysis based on ITS rDNA, Calmodulin and β-tubulin sequences. The relation between A. pseudodeflectus and other species of Aspergillus Section Usti was also discussed. This was the first report of ophiobolins produced by A. pseudodeflectus.

Abstract:In order to obtain genomic DNA which meets the requirements of DNA-DNA hybridization, CTAB method combined with liquid nitrogen grinding was investigated. Cultures from different media added with glycine were harvested in different time. Quality of extracted genomic DNA was assessed by electrophoresis and OD260/OD280 value. Mycelia of shaking culture in yeast extract & malt extract (YE) medium containing 0.3% glycine for 3 days were subjected for DNA extraction. The genomic DNA obtained was about 20 kb, with the OD260/OD280 value around 1.8.

Abstract:Phenols are important secondary metabolites in plant tissues, and provide well protection against the attacks by pathogenic microbes. Arbuscular mycorrhizal (AM) fungi can induce the biosynthesis of phenols in plants both locally and systematically. Recently, research has been intensively reported on this aspect. In this paper, the localized and systematic induction of phenols by AM fungi is reviewed. The possible signaling molecules (SA, H2O2) in the induction process are put forward, and the putative action model involved in the biosynthesis of phenols induced by AM fungi is further presented. Some research perspectives for the future are also pointed out.

Abstract:Luminescent bacteria are those ubiquitously distributed microorganisms that emit visible light due to their naturally existed light-production genes: lux. A bioluminescent test, which offers benefits of rapidity, sensitivity and reproducibility for routine toxicity monitoring, gained growing attention these years, and it is usually chosen as an effective tool for early warning system based on its quick response and low cost. Genetic manipulation involvement equips the bioluminescent assays using several specific responsive strains with the ability of toxicity classification. This paper reviews the latest progress in luminescent bacteria for environmental toxicity testing. Description of the luminescent bacteria assays including natural luminescent bacteria test, light-emitting genetically modified bacteria test, as well as the recent research of the utilization of the bioluminescent assay for determination of water quality are all reviewed in this article.

Abstract:Loop-mediated isothermal amplification (LAMP) is a novel nucleic acid amplification method that amplified DNA with high specificity, efficiency and rapidity under isothermal conditions using a set of four specially designed primers and a DNA polymerase with strand displacement activity. The cycling reaction continues with accumulation of 109-1010 copies of target in less than an hour. The final products are stem-loop DNA with several inverted repeats of the target and cauliflower-like structures with multiple loops. A positive reaction would be shown as a ladder-like pattern in a gel electrophoresis analysis. Because of its simplicity, high sensitivity and specificity, the LAMP method has been widely applied to the field of food safety inspection.

Abstract:In order to explore the application effects of WPBL didactics in the education of “Microbiology Laboratory”. 66 students majoring in laboratory diagnostic medicine were respectively divided into two teaching groups. The WPBL didactics was carried out in the experimental group while the traditional didactics was used in the control group. Theoretical tests were performed to both groups and questionnaire was given to the experimental group at the end of the class. The statistical the experimental group test results clearly superior to the controls (P < 0.01), and the pass-level differences of theoretical test between two groups have statistical significance (P < 0.05); and over 90% of the students were interested in the WPBL didactics as they considered it effective to improve their learning interests, self-learning ability and problem-solving skills. From the result, WPBL didactics can enhance the teaching quality of “Microbiology Laboratory”.

Abstract:Biochemistry is a fundamental and advanced subject in the field of life science. It’s also a course with difficulties in both teaching and learning. These features make it necessary for teachers to ceaselessly update teaching concepts, explore and create new teaching methods and means. Practice shows that satisfactory in-class teaching efficiency of this course can be achieved by flexibly adopting frameworks and icons, PBL methodology, comparative methodology, CBS methodology, and metaphorical teaching methods. Meanwhile, the integrated use of multimedia, bilingual education and other teaching methods also contributes to the improvement of the in-class teaching efficiency. With the help of the above teaching methods and means, abstract and difficult knowledge will become definite and easy. Students can also systematically master theoretical knowledge.

Abstract:Staphylococcus aureus can cause alimentary toxicosis, contamination of which could exert a great influence on food safety and export processing of aquatic products. In this study, TEMPO/STA method was used for enumeration of Staphylococcus aureus in 535 aquatic samples, and compared with PetrifilmTM Staph Express Count Plate method. TEMPO/STA method was demonstrated to be a rapid and accurate method, with a good agreement (96.6% compliance rate, no difference in accuracy) with the other one.

Abstract:To analyze the diversity and dynamic changes of predominant bacteria during ensiling, the silage fermented in natural and silage treated with inoculants,which named CK and unit 1 respectively, were sampled in the case of days 0, 1, 3, 5, 15, 30, 60. The pH of each sample was measured and the genomic DNA of microorganism was extracted respectively. After purified by DNA gel Recovery kit, the genomic DNA was subjected to PCR with 16S rDNA (V3 region) primers (341F-GC and 518R). The amplified DNA fragments were separated by denaturing gradient gel electrophoresis (DGGE) and the dominant bands were excised for sequence analysis. The results showed that the pH of unit 1 dropped more rapidly than that of CK, the species of predominant bacteria and numbers of each species also more abundant.