Abstract:

Abstract:[Objective] Analysis microbial diversity of chilled beef with MAP (modified atmosphere packaging, 65% O2 and 35% CO2) and conventional packaging during storage (4?°C). [Methods] PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) of V3 area fragment of 16S rDNA and cloning analysis method of 16S rDNA were used to analysis the microbial diversity and dynamic changes of predominant bacteria in chilled beef with MAP and conventional packaging. [Results] Psychrobacter and Pseudomonas were the initial dominant bacteria. During storage, Pseudomonas and Brochothrix turned into the dominant bacteria in chilled beef with conventional and MAP packaging. The species of bacteria in beef with conventional packing were more abundant, and bacteria changed significantly at earlier storage. [Conclusion] The results showed a big difference in microbial community structure between two kinds of packing beef, and indicated that CO2 played a certain inhibitory action in beef with MAP.

Abstract:

Abstract:[Objective] A melanin-producing actinomycete was isolated from the mud collected from Gaogong Island, Lianyungang. [Methods] The pigment seperated from the fermentation broth of HT-18 was characterized by UV-visible absorption spectroscopy and infrared spectroscopy. The strain was clarified by colonial morphology, physiological and biochemical tests and 16S rRNA sequence phylogenetic analysis. The shake flask condition for pigment fermentation was optimized using single factor test. [Results] The results showed that HT-18’s production was melanin. The strain was preliminary identified Streptomyces. The optimal fermentation process was that 70 mL of tyrosine medium was contained in a 250 mL flask for 3 d fermentation at initial pH 7.0, 31 °C. [Conclusion] HT-18 was a melanin-producing strain with research and application potential.

Abstract:[Objective] By screening of chitosanase strains in mud samples from the Fujian coastal intertidal with screening medium, studied the characteristics of the strains for enzyme production. [Methods] Through morphological observation, combined with 26S rDNA sequences were classified and identified, DNS method was use for the determination of enzyme activity. [Results] The conclusion showed a 99% similarity between the chitosanase strain KQ-1002 and Penicillium oxalicum. The strain was tentatively identified as a species of Penicillium fungus. The optimal fermentation temperature was 30 °C, the optimum carbon source was the 1.0% soluble chitosan, the optimal nitrogen source was 1.87% (NH4)2SO4, and the optimum pH was 6.0. Cultured for 72 h under liquid fermentation on the strains, the chitosanase-producing activity reached the maximum, and the maximum of enzyme production had been optimized to 18 U/mL. The molecular masses of purified enzymes was 40 kD which analyzed by SDS-PAGE. Enzymatic reactions’ optimum pH was 5.0, the optimum temperature was 55 °C, and Km was 1.293 g/L. When ion concentration reached 1.0×10?3 mol/L, metal ions of Cu2+, Hg2+, Ag+ would strongly inhibit the enzyme’ activity. There was a different degradation of chitosanase on various substrates and deacetylation of chitosan. [Conclusion] Through screening, the chitosanase activity of chitosanase-producing fungal strains KQ-1002 which had been optimized boosted by approximately 7 times, and it is a chitosanase-producing strains of research and potential applications.

Abstract:[Objective] The aim of the present study was to provide the excellent strain resources for the production of Cerasus pseudocerasus bio-fertilizer. [Methods] Bacterial isolates were isolated and screened from the rhizosphere soil of Cerasus pseudocerasus using the methods of remaining green and radish cotyledon bioassay. And then, plant hormones produced by the bacterial isolates were quantitatively detected. Additionally, a pot experiment was conducted to determine whether the use of the bacterial isolates benefits the growth of Cerasus pseudocerasus. At last, the bacterial isolates that exert beneficial effects were identified based on the results of morphologic characteristics, physiological biochemical properties and phylogenetic analysis of 16S rRNA genes. [Results] Four plant growth-promoting rhizobacteria (PGPR) with potential beneficial effects on Cerasus pseudocerasus growth were screened. According to the pot experiment results, AI5, AI21, PII17, and PI7, especially PII17 can significantly improve the root and aerial part biomass of Cerasus pseudocerasus, showing the beneficial effects on Cerasus pseudocerasus growth. AI5 and AI21 were identified as Bacillus pumilus. PII17 and PI7 were identified as Pseudomonas sp. and Enterobacter sp., respectively. [Conclusion] AI5, AI21, PII17, and PI7, especially PII17 that exert beneficial effects on Cerasus pseudocerasus growth exhibited broad application prospects in the bio-fertilizer production.

Abstract:[Objective] To identify pathogenic bacteria isolated from dead goslings suspected Riemerella anatipestifer disease. [Methods] The isolated bacterial strain was subjected to examine by the cultural performances, biochemical properties, animal text, serological identification and biological features. [Results] The results showed that the isolated strain was identified as gram-negative bacteria, which could not ferment and alcohols, and it was positive of ureolysis test and oxidase test. Pathogenic. The multiple sequence alignment from different isolated stains 16S rRNA genes showed, the strain in this study was at the same evolution branches with the Riemerella anatipestifer isolated from ducks, but it was in little relation to the Riemerella anatipestifer isolated from chicken. It belongs to the serotype I of Riemerella anatipestifer. [Conclusion] The isolated bacterium belongs to the serotype I of Riemerella anatipestifer, which was highly pathogenic to the ducking and goosing, and the self-development vaccine could protect the goslings effectively against to be infected by Riemerella anatipestifer.

Abstract:[Objective] To screen the 1-deoxynojirimycin producing strains by employing high performance liquid chromatography with pre-column derivatization and then perform phylogenetic identification. [Methods] High performance liquid chromatography with 9-fluorenylmethyl chloroformate (FMOC-Cl) pre-column derivatization was a way of screening the DNJ producing strains. The polyphasic taxonomic characteristics, including morphological, physiological and biochemical characteristics, as well as comparative sequence analysis of 16S rDNA were used to identify strain. Then, a fermentation study was carried out on the scale of 10 L fermentor and DNJ content was determined by high performance liquid chromatography with 9-fluorenylmethyl chloroformat (FMOC-Cl) pre-column derivatization. [Results] A DNJ producing strain, namely PW409, which was subsequently identified as Streptomyces gobitricini, was obtained from 80 actinomycetes strains possessing α-glucosidase inhibitory activity. Fermentation study showed that DNJ belonged to a secondary metabolism of strain PW409, and the concentration of DNJ in fermentation broth was 12.1 mg/L. [Conclusion] This article first applies high performance liquid chromatography with 9-fluorenylmethyl chloroformat (FMOC-Cl) pre-column derivatization to screen DNJ producing strains as well as first identifies DNJ from the fermentation broth of Streptomyces gobitricini.

Abstract:[Objective] Microorganisms from high temperature seaweed beds on Kalianda Island of Indian Ocean were isolated, cultivated, and identified based on 16S rDNA sequences. Study on characteristics of thermo and salt tolerances of selected isolates were also carried on. [Methods] Samples of alga Sargasso sp., sediment and water from seaweed beds were collected. Using MGYTC medium, microorganisms from the samples were cultivated and purified at 55 °C and 30 °C, respectively. Species identification was determined based on 16S rDNA sequences and phylogenetic tree was built afterwards. Effects of culture temperature and salinity on bacterial growth were determined. [Results] A total of 12 strains belonged to four classes and nine genuses were obtained, and the maximum similarities were higher than 98% with known species. Two strains belonged to different genus of thermophilic actinomycetes, and two Bacillus strains obtained at 55 °C were thermophile. Laceyella sacchari and Bacillus thermoamylovorans can survive at the range of 0–90 salinity. Shewanella upenei, Shewanella algidipiscicola and Shewanella haliotis belonged to γ-Proteobacteria could grow at the temperature of 30 °C–55 °C. [Conclusion] The strains obtained had features of thermo and salt tolerances, or adaptability to wide temperature range, which were expected to be new resources in biotechnology field. The isolates of Tepidibacter formicigenes, Exiguobacterium profundum and Vibrio diabolicus had been originally reported from the deep-sea hydrothermal area, suggesting the internal relations of marine hot spring system and deep-sea hydrothermal environment.

Abstract:[Objective] In order to study the antimicrobial activity of Gal-7 mature peptide in vitro, we constructed an engineered E. coli strain contains chicken beta-defensin-7 (gal-7) gene encoding Gal-7 mature peptide published previously. [Methods] Based on the gene sequence, we synthesized the gal-7 gene, cloned into pGEX-6p-1 prokaryotic expression vector and subsequently transformed into the E. coli BL21(DE3). The E. coli strain contains the expression vector was induced with IPTG and the fusion protein GST-Gal7 was purified by affinity chromatograph, then Prescission protease was used to remove GST-label to form Gal-7 mature peptide. The molecular weight of purified Gal-7 mature peptide was monitored by MALDI-TOF-MS and antimicrobial activity was tested by the agar well diffusion assay. Besides 2-fold dilution method was used to determine the minimum inhibitory concentration of Gal-7 mature peptide. [Results] We successfully constructed the engineered E. coli strain expressing pGEX-6p-Gal7 and GST-label was cleaved by Prescission protease. The molecule weight of purified Gal-7 mature peptide was 5 516 D, it exhibited antimicrobial activity against Micrococcus flavus (NCIB 8166), S. aureus (ATCC 25923), E. faecalis (ATCC 29212), E. coli (CMCC 44102) with MICs 16.875, 67.5, 67.5, 135 mg/L respectively. [Conclusion] The GST-Gal7 protein was successfully expressed in E. coli, besides the Gal-7 mature peptide without GST-label showed antimicrobial activity against several indicator strains.

Abstract:[Objective] Establish purification methods of fibrinolytic enzyme with high purity and fibrinolytic activity from Paecilomyces militaris submerged culture liquid and determine its characterization. [Methods] The fibrinolytic enzyme Ⅱ of Paecilomyces militaris was purified by ammonium sulfate precipitation, Sephadex G-25 gel filtration chromatography, Phenyl-Sepharose HP hydrophobic interaction chromatography, CM-Sepharose FF ion exchange chromatography and Superdex 75 gel filtration chromatography. The protein concentration of enzyme Ⅱwas determined by Lowry method. The fibrinolytic activity was determined by Fibrin plate method. The purity and molecular weight was estimated by SDS-PAGE. The isoelectric point was estimated by isoelectric focusing electrophoresis. [Results] We found that Paecilomyces militaris produced at least two kinds of fibrinolytic enzymes by submerged cultivation, sucrose and bean cake as major materials. The specific activity of purified fibrinolytic enzyme Ⅱ was 800.46 U/mg and the purification protocol resulted in 30.07-folds purification of the enzyme Ⅱ. The molecular weight and isoelectric point of the enzyme Ⅱ was 32 kD and 9.3±0.2, respectively. The enzyme Ⅱwas a glycoprotein, the total sugar content of it was 0.98% (w/v). The enzyme Ⅱ could degrade α, β and γ chains of human fibrinogen. The optimal pH and temperature of the enzyme were 7.4 and 41°C. The fibrinolytic activity was completely inhabited by Aprotinine and PMSF, which indicated that it might be a serine protease. [Conclution] The acquisition of enzyme with single and high fibrinolytic activity and the determination of its characterization, which provides theoretical basis for the enzyme to become a new thrombolysis drug.

Abstract:Staphylococcus employs SrrAB, a two-component signal transduction system (TCSTS), to sense and respond to changes in oxygen tension by regulating transcriptions of downstream genes. It has been demonstrated that under aerobic condition SrrAB upregulates the expression of virulence factors and inhibits biofilm formation in S. aureus, however under anaerobic condition it downregulates the expression of virulence factors, and enhances biofilm formation. In addition, SrrAB plays different roles in growth and metabolism under aerobic and anaerobic conditions in S. aureus. Little is known about the function of SrrAB in S. epidermidis, which shares considerable homology with SrrAB of S. aureus. In combination with previous work of our laboratory, we review the advances of current research of staphylococcal SrrAB, with the comparison of SrrAB modulation mechanism under aerobic and anaerobic conditions highlighted.

Abstract:Benzoic acid is becoming a common pollutant in the environment because of its widely use in industry. We summarized different pathways of the aerobic and anaerobic degradation of benzoic acid by microorganism. Both the two- and three-component benzoic acid dioxygenases play important roles in the process of benzoic acid degradation. Gene clusters of benzoic acid degradation and regulation were introduced, and also the direction of pollution degradation by microorganism in the future.

Abstract:To establish the experimental evaluation system taken the experiment process management as the foundation, the reasonable evaluation index as the core, and the evaluation of students’ comprehensive experimental ability as the goal, with the implementation of the reform of medical microbiology disciplines experimental teaching. To construct a reasonable evaluation index, to evaluate students’ basic technical ability, scientific experimental thought, and comprehensive exploring ability scientifically at different levels. To issue questionnaires and to interview with students in order to find out whether the reform is successful. As can be seen from the questionnaires and interviews, the reform of evaluation system turned out to be successful. The new experimental evaluation system can reflect students’ experimental and comprehensive abilities with the incomparable superiority to the traditional one.

Abstract:The core curriculum reform of the bioengineering major has been investigated focusing on emphasizing the comprehensive qualities, enhancing the education of engineering ability and accomplishment, improving the knowledge structure. The engineering qualities contents were illuminated with the five kinds of capabilities and five kinds of awareness, which must be possessed by the bioengineer. The main core curriculum was determined for training the engineering qualities. Based on the cooperation of Industry-University-Research, the double qualified teachers’ were improved. Focusing on training the engineering ability, the characteristic course group was constructed by the main lines of bioengineering factory design and the technology improvement. The teaching methods of some core curriculum, for example, heuristic teaching, group discussion, comparison and summary method, etc. were put forward to increase the teaching efficiency and enhance the engineering qualities of the students.

Abstract:[Objective] To develop a loop-mediated isothermal amplification (LAMP) method for detection of Saprolegnia. [Methods] Four specific LAMP primers (two inner primers and two outer primers) were designed by targeting ITS gene of Saprolegnia. After optimizing reaction condition, the positive results of LAMP assay were judged through visible green colour. To evaluate the sensitivity and specificity of the assay by detection of Saprolegnia spore samples. [Results] The method of a loop-mediated isothermal amplification (LAMP) for detection of Saprolegnia was established. The sensitivity was 103 spores per mL and was 100 times higher than normal PCR. [Conclusion] LAMP assay is specific and simple to operate without the need of special equipment, our assay presents a promising method for detection of Saprolegnia and its spores.

Abstract:[Objective] To differentiate two strains of Escherichia coli from different sources by fourier transform infrared spectroscopy (FT-IR). [Methods] FT-IR fingerprint absorption spectra of two strains of E. coli from different sources were collected and analyzed by chemometric methods. [Results] Two cluster models of principal component analysis (PCA) and hierarchical cluster analysis (HCA) were established and could differentiate well the two strains of E. coli. [Conclusion] As a rapid, easy-to-use and accurate technique, FT-IR spectroscopy can be used to differentiate microorganisms at the strain level from different sources.