Abstract:

Abstract:A mangrove actinomycetes strain zxy19 that has shown strong xylanase activity was selected by plate screening. Sequencing analysis and Blast search of the 16S rDNA gene of the strain revealed that the highest identity in the database was 96% against Streptomyces sampsonii. Characterization of the xylanase enzymatic properties of zxy19 has shown that the optimal pH was 7 and the optimal temperature was 60°C. Degenerate primers were designed according to the conservative domains of actinomycetal xylanase to amplify the partial xylanase gene. The complete enzyme gene xyl696 was obtained by inverse PCR subsequently and confirmed by DNA sequence analysis. Blast search of the translated amino acid sequence suggested that the enzyme belongs to the glycosyl hydrolases family 11 with the highest similarity as 79% against the xylanase B produced by Streptomyces lividans. The xylanase gene was cloned into the expression vector to construct pET-28a-xyl696 and introduced into E. coli BL21(DE3). After IPTG inducing, the over expressed recombinant xylanase was purified by Ni2+-NTA affinity chromatography and proved to have catalytic activity.

Abstract:A possible β-Galactosidase gene (pwtsA) was discovered from soil metagenomic DNA of Taishan Mountain. PwtsA gene was inserted into the expression vector pET30a and transferred into E. coli BL21(DE3). Recombinant protein PWTSA was expressed as a soluble form at high level through IPTG induction, with a molecular mass of 57 kD analyzed by SDS-PAGE. PWTSA can produce o-nitrophenol from o-nitrophenol-β-D-galactopyranoside (ONPG), and its specific activity was determined as 13.6 U/mg. The enzymatic studies demonstrated that the recombinant protein PWTSA was a thermostable β-Galactosidase, its optimum temperature and pH were 85°C~95°C and 6.5 respectively. In standard assays, the Km for ONPG was 0.83 mmol/L.

Abstract:112 aerobic moderate halophilic bacteria were isolated from Daong Ancient Brine Well located in Zigong city, Sichuan Province, China. And they were subjected to the analysis of phenotype, physiology, 16S rRNA sequence. Furthermore, the intra specific phylogeny of closely related strains was also screened by PCR fragment length polymorphism of 16S-23S ribosomal RNA intergenic spacer regions (ISR). The result showed that the halophilic isolates found in current study were closely related to the following genera: Planococcus, Halomonas, Halobacillus, Oceanobacillus and Virgibacillus, a lineage of the domain Bacteria. 16S rRNA analysis revealed that their sequences sharing 100% and 99% similarity were obtained from the GenBank database for P. rifitiensis, H. venusta, H. trueperi, H.blutaparonensis, O. profundus and V. pciturae. However, isolates QW06、QW12、QW15 and QW18 exhibited differences from their corresponding reference strains to some degree, including colony pigmentation, gram staining, acid production and hydrolysis of gelatin, casein and starch. The ISR analysis disclosed variation of banding pattern in these isolates related to Oceanobacillus and Halobacillus which was observed with phenotypic and physiological characterizations as well. It was clear that these halophiles have adapted to the special man-made hypersaline environment by the basic physiological evolution during phylogenesis. So they could be determined according to further polyphasic taxonomy data. The current primary result also indicated the diversity of species of culture-dependent moderately halophilic bacteria colonizing in Dagong Ancient Brine Well as well as phenotypic and genotypic and phylogenetic diversity.

Abstract:Phylogenetic diversity of halophilic actinomycetes from hypersaline environments in Tarim basin was investigated by using culture-dependent method and phylogenetic analysis based on 16S rRNA gene sequences. The results showed that the eighteen isolates, which were isolated from different hypersaline soil samples isolates belongs to three different families(Glycomycetaceae, Pseudonocardineae and Nocardiopsaceae) of the order Actinomycetales, and the most abundant and diverse isolates were within the Actinopolyspora(38.9%), Nocardiopsis(27.8%) and Streptomonospora(22.2%). In addition, four of the five known genera isolates were obtained for those halophilic Actinomycetes. Interestingly, strain YIM 92370 formed one distinct clade in phylogenetic tree based on 16S rRNA gene sequences among the family Glycomycetaceae, and it was noted that strain YIM 92370 is phylogenetically nearest to the genera Glycomyces and Stackebrandtia, but apparently is not a member of the two known genera or any of the other currently described actinomycetal genera. So it is proposed that the strain represents a new genus within the family Glycomycetaceae with 92% sequence similarity with the described species of this family. The results indicated that there was not only abundant phylogenetic diversity of halophilic actinomycetes, but also some unknown actionobacterial groups existed in hypersaline environments in Tarim basin.

Abstract:Poly γ-glutamate is a biopolymer material that has a good application prospect. The Vitreoscilla hemoglobin(VHb) gene was integrated into the chromosome of Bacillus licheniformis WX-02 by integrative vector pDG1730-vgb. The expression of VHb was confirmed by CO-difference spectra analysis. It was shown by the results of batch cultures in a 3 L bioreactor that biomass and γ-PGA obtained in the recombinant M2 were 25.5 % and 20% higher than those of the control respectively.

Abstract:Using PCR and RACE technique, We obtain the cDNA and genomic DNA sequence of the lac1 gene from Auricularia polytrica. The length of genomic DNA is 2514 bp, which contains 14 exons and 13 introns based on the comparison of cDNA and genomic DNA sequence. The length of the lac1 cDNA sequence is 1972 bp, which includes a complete Open Rading Frame (ORF)of 1860 bp, from N0.33 to No.1890, encoding 619 amino acides, the molecular weight is about 68 kD, and isoelectric point is about 5.15. A signal peptide sequence exists in the N-terminal of the deduced amino acids, which also contains three multi-copper oxidase domains: KOG1263, SufI and pfam00394. We blasted the deduced amino acids with the fungal laccases protein sequences on the GenBank and observed that there is higher homologous similarity: the highest identity is 41% and positive is 58% respctively, and it also includes four conserved Cu-bind domains. The full length cDNA sequence of A. polytricha lac1 gene was ligated to the pPIC9K to construct expression vector pYH3660, the recombinant plasmid pYH3660 was transformed into Pichia pastoris, laccase activity was detected from the engineering strain which was induced by methanol with the highest expression level(123 IU/L). At same time, we get the anticipative protein using the Native SDS-PAGE. Based on the analysis of the sequence structure and expression characterization, we can conclude that the lac1 gene obtained from Auricularia polytrica is laccase gene.

Abstract:16S rDNA-PCR-DGGE, a cultivation-independent approach, was used to analyze the bacterial communities in paddy soils in Fujian Province. The bulk soils and rhizosphric soils were sampled from six different ecological soil regions. Total DNA was directly extracted and amplified with the F341GC and R534 primers targeting the 16S rDNA V3. The amplified fragments were analyzed by perpendicular DGGE. Cluster analysis revealed that there was a high diversity of bacterial community compositions among different soil samples tested. Basically they could be grouped to Mindong (East), Minnan (South), Minbei (North) and Minxi (West) ecological regions. 16S rDNA-PCR-DGGE profiles from bulk and rhizospheric soil in the same region showed less bacterial diversity but more similarity. The bacterial community from bulk soil and rhizospheric soil in Longyan shared the most similar DGGE banding patterns, and the banding patterns in Yongtai exhibited the highest diversity. Eleven DGGE bands recovered were re-amplified, sequenced and aligned with Blast. The results indicated that ten of the fragments belong to uncultivated bacteria implying DGGE technique having priority in analyzing uncultivated bacteria in the paddy soils.

Abstract:Field studies were conducted for a season to determine potential for alterations in the rhizosphere fungi quantity dynamics and dominant populations of 4 wild sugarcane clones(S. spontaneum L.) with different UV-B sensitivity under an enhanced ultraviolet-B (UV-B, 280 nm~310 nm) radiation. The quantity of rhizosphere fungi was most in tillering stage, second in seedling stage and lest in elongating stage and maturing stage, the sequence wasn’t alternated by UV-B radiation. The rhizosphere fungi quantity of tolerant clone was obviously increased and greater than the sensitive clone under the enhanced UV-B radiation, however, the number of dominant populations decreased and Penicillium was the dominant population during the periods of 4 wild sugarcane clones.

Abstract:Special PCR primers were designed from the sequence of 16S-23S ribosomal RNA of Pseudomonas fluorescens, then these primers were used to screening 400 bacteria strains which selected from tobacco planting soil. In the experiment, 21 Pseudomonas fluorescens strains which contain Pyrrolnitrin had been identified, and 1 Pseudomonas fluorescens strain which contain 2,4-diacetylphloroglucinal and Phenazine-1-carboxylic acid had been identified, too. The results showed that the strain which contain 2,4-diacetylphloroglucinal and Phenazine-1-carboxylic acid inhibit to tobacco anthracnose.

Abstract:Two N2-fixing isolates, B11S and B8S, were obtained from the surface-sterilized stalks of sugarcane variety GT11and RB86-7515 which were bred in Guangxi, China and introduced from Brazil, respectively. Both isolates showed acetylene reduction in nitrogen free media. Classification of both B11S and B8S was made on the basis of 16S rRNA sequence analysis, and the biological characteristics of the two isolates were studied. The 16S rRNA sequence of the isolate B11S had a 98.5% sequence similarity to those of many Stenotrophomonas maltophili and the 16S rRNA sequence of the isolate B8S had a 100% similarity to that of Agrobacterium tumefaciens (Rhizobium radiobacter). For both growth and nitrogenase activity of the isolates, the optimum temperature was about 31°C. The optimum pH was about 6.0 for their growth but 6.5~7.0 their nitrogenase activity. The two strains propagated more quickly and showed higher nitrogenase activity with the increase of carbon concentration in the culture media, and the effect of sucrose was better than that of the glucose. The growth and nitrogenase activity could be detected when the two strains were cultured in the media containing different concentration NH4+ and NO3-, and they grew better and showed higher nitrogenase activity under suitable nitrogen contents, but the growth of the two isolates was hindered more and more strongly with the increasing of the nitrogen content.

Abstract:To screen effective and affinity plant growth-promoting rhizobacteria strains (PGPR) that can react with cotton lectin from cotton rhizosphere, we isolate nitrogen-fixation bacteria, phosphate-releasing bacteria and potassium-releasing bacteria from cotton rhizosphere by Ashby medium, phosphate-releasing bacteria medium and potassium-releasing bacteria medium, respectively. The strains were re-screened by cotton lectin labeled with fluorescein isothiocyanate. According to their ability of nitrogen-fixation, p-releasing and K-releasing in pure culture condition, 2 strains of nitrogen-fixation bacteria, 2 strains of phosphate–releasing bacteria and 2 strains of potassium-releasing bacteria were inoculated as microbial fertilizers in pot experiment of cotton, respectively. About 20%~30% strains of PGPR had positive reaction with cotton lectin labeled by FITC among the PGPR. Study showed that the numbers of PGPR in cotton rhizosphere were about 10 times of those of controls sterilized. Pot test data suggested the 6 strains have certain affinity with cotton and can propagate in cotton rhizosphere. Through preliminary identification of 6 affinity strains, the strain of N1111 was identified as Azotobacter and N2121 was classified as Derxia. P2126 and P1108 were Xanthomonas and Pseudomonas, respectively. K2204 and K2116 were Bacillus.

Abstract:The total amount of colony forming units (CFU) of bacteria, fungi and actinomycetes in the rhizosphere and surrounding soils were investigated at four different growing stages of tomato plants using traditional plate-counting method. The amount of bacteria reached its peak value at the blossoming stage and the fruiting stage. From seedling stage to late period, actinomycete number decreased gradually with time, but fungi increased. For bacteria, the rhizosphere effect of tomato plant (R/S) was the highest at the early blossoming stage and the early fruiting stage. The variation and diversity of microbial populations in the rhizosphere soil of tomato plants were also studied using cultivation-independent analysis. DGGE profile indicated high diversity of microbial populations in the rhizosphere soil at different growth stages. The bacterial species kept stable but the population of particular species changed in different patterns. Manifest change in rhizosphere bacterial species and populations occurred at the early blossoming stage, and the most abundant bacterial species was observed at the early fruiting stage. This investigation successfully revealed the community features of the culturable and unculturable microbes in the rhizosphere soil of tomato plants, and indicated that the most abundant bacterial species occurred at the fruiting stage, suggesting this stage a suitable period for screening antagonistic bacteria.

Abstract:Bacillus thuringiensis strain 519-1 was tested for the antagonistic activity against the growth of hyphae of eight fungi including Aspergillium niger, Botrytis cinerea, Fusarium graminearum, Fusarium oxysporum, Penicillium chrysogenum, Physalospora piricola, Rhizoctonia solani, Rhizopus nigricans. It could notably inhibit sporangia germination of all the tested fungi. The culture of 519-1 exhibited high toxicity against Spodoptera exigua and Helicoverpa armigera, with LC50 values of 5.5 μg/mL and 12.5 μg/mL, respectively. PCR analysis with specific primers showed that the strain contained five insecticidal protein encoding genes: cry1Aa, cry1Ab, cry1Ac, cry1I, cry2 and a vegetative insecticidal protein gene, vip3A. Cry proteins with molecular weight about 135 kD~130 kD、95 kD、80 kD、70 kD and 65 kD~60 kD were detected using SDS-PAGE. The chitinase was expressed from the strain independent of any chitin. The results showed that Bt519-1 was a strain which had high activities of broad-spectrum antagonistic and high insecticidal toxicity against lepidopteran pests.

Abstract:The thermotolerant bacteria which was isolated from the Apple Juice Concentrate (AJC) was investigated by comparison with the standard strain of Aliyclobacillus acidoterrestris DSM3922 using Kirin-medium acidified with malic acid. The results shows the two polluted bacteria isolated from AJC can grow under the temperature of 21°C~55°C and pH of 2.4~6.2, which was corresponded with the characteristics of the thermo-acidiphilic Alicyclobacillus spp.. Further more, the cell morphology, colony morphology, cultural characteristics and physiological characteristics tests indicated the two isolated strains of thermotolerant bacteria have obviously similar characteristics with the standard strain of Aliyclobacillus acidoterrestris DSM3922.

Abstract:The nucleic acid fragment of porcine circovirus type 2(PCV2)was amplified using PCR from the tissues of a domesticated wild boar with suspected postweaning multisystemic wasting syndrome (PMWS). The sample were then inoculated into the Dulac cells and passaged for 8 generation. The 4 nucleic acid fragments covered the complete genome for PCV2 were obtained by over-lapping PCR and sent to sequence. The sequence of genome was compared with other 9 strains originated from piglets in the same area. The result showed that these strains were in high homology.

Abstract:It was about the initially research in the kinetics of inhibiting acetylcholinesterase(AChE)of endophytic fungi g5 which Isolated from Huperzia serrata. In addition, morphologic determination was done with this fungus. The effect of EtOH extraction from g5 fermentative product on the inhibiting AChE was detected by coloration of DTNB method, and this fungus was determinated by slide culture. The result is that g5 belongs to Penicillium rugulosum. According to Initially analysis of enzyme kinetics, it was showed that g5 was admixed competitive reversible inhibitory type, and the inhibit-constant KI against free E and KIS against comoles compound of ES is 0.0789 mL and 1.1352 mL, respectively. The metabolic product of g5 can be developed as potential drugs which is not only conspicuous but also reversible inhibiting AChE in vitro.

Abstract:The aim of this study was to explore the effect of inflammation-mediated by NF-κB on lung injury of mice with invasive pulmonary aspergillosis. The mice were divided into three groups including the group of normal mice, the group of normal mice with infection and the group of IPA mice. The mice were sacrificed on day 4 post-infection. The lung tissues from each group were collected for observing the pathological alteration, evaluating histological scores of NF-κB p65 with immuno-histochemistry stain, detecting mRNA expression level of TNF-α and IFN-γ in comparison to β-tublin in ratio of densitometric units using RT-PCR and measuring MPO of neutrophils with colorimetry. The pathological analysis showed the normal structure and no inflammatory reaction in the lungs of the normal mice; and the infiltration of inflammatory cells, weak injury and no germination of spore into hypha in the lungs of normal mice infected with A. fumigatus and serious injury like destruction of alveolar structure, bleeding and germination of spore into hypha in the lungs of IPA mice. The expression level of TNF-a and IFN-γ, histological score of NF-κB p65 and activity of MPO in both groups of normal mice infected with A. fumigatus and IPA were higher than in the normal mice group(P<0.05). But histological score of NF-κB p65 and activity of MPO in IPA mice were higher than in normal mice infected with A. fumigatus(P<0.05). The results suggested that the expression of TNF-a and IFN-g as well as recruitment of neutrophils that were promoted by the signal pathway mediated by NF-κB activated by infection of A. fumigatus may be one of the factors that cause the seriously pathological injury of lungs in the mice with invasive pulmonary aspergillosis.

Abstract:Recently, plant endophytes attract much attention due to their special ecological significance. Here reviewed is the recent research advances in plant-endophyte interaction. Specifically, we mainly focused on the beneficial effect of endophytes realized by growth-promoting and production of pathogen resistant substances. We also reviewed one of the recently concerned areas that endophytes obtain high adaptabilities by forming biofilms on the tissue surfaces of their host plants. Finally, using symplasmata formed by rice endophyte Pantoea agglomerans YS19 as an example, the physiological and ecological significance of these multicellular aggregations and their researching future were discussed.

Abstract:Canthaxanthin (4, 4′-diketo-β, β′-carotene) is a keto-carotenoid with strong antioxidant activity but no provitamin A activity. Canthaxanthin has potential and promising applications in human health and nutrition. The intake of canthaxanthin has proved to potentiate immune responses, enhance gap junctional communication and protect against skeletal diseases, UV-induced skin damage and some cancers. Synthetic canthaxanthin dominates the world market but recently interest in natural sources of the pigment has increased substantially. The major biological sources of canthaxanthin include crustacean and crustacean extracts, fungi, bacteria, yeasts and microalgae. Currently, only a few mutant strains of the bacteria are being considered or already being exploited for the production of high-value canthaxanthin, including Brevibacterium sp KY-4313, Haloferax alexandrinus sp. nov. TM, Gordonia jacobaea MV-26, Dietzia natronolimnaea HS-1. The current review summarized and discussed the general properties, the medicinal applications, biosynthesis, and promising natural sources of canthaxanthin, as well as recent developments in the biotechnological production of canthaxanthin.

Abstract:Antimicrobial peptides are a class of small peptides with anti-extrogenous pathogen activities. They are derived from organism and possess antibacterial, antifungus, antiviruses and anticancer cell actions. In recent years, it’s found that some microbial pathogens are able to resist antimicrobial peptides. The constitutive and inducible mechanism of a pathogen resists a given peptide were reviewed in this paper.

Abstract:Black yeasts are a group of polymorphic yeast like fungi which produce melanin. They always grow slowly and have high stress resistance ability. The taxonomy, ecology, stress resistance, pathogenicity, and melanin of black yeasts are reviewed in this paper. Hortaea werneckii is an interesting novel model organism for studies on salt stress-responsive proteins as well as on sterol biosynthesis in eukaryotes. Aureobasidium pullulans is also like a model organism for studies on the regulation of polymorphic cell development.

Abstract:Malolactic fermentation (MLF) is performed principally by Oenococcus oeni in order to improve the stability and quality for winemaking. MLF usually occurs either spontaneously or after inoculation with selected bacteria. The functions of Saccharomyces cerevisiae, phenolic compounds and winetechnics to Oenococcus oeni were summarized in this review. The effects of wine physic-chemically harsh conditions on the Metabolism of Oenococcus oeni were discussed. We look forward to the information being the references for MLF controlling.

Abstract:Phospholipase D (PLD) is ubiquitous in bacteria, fungi, and mammal. In pathogenic microorganisms, PLD can be pathogenic determinant and play a role in spore generation. In mammalian cells, PLD functions in several signal transduction pathways, such as membrane transportation, mitosis regulation, and actin cytoskeleton regulation. In the process of pathogens invasion host cells, both of the pathogen and host cells’ PLD will be activated and a series of cascade reaction will be generated. During this process, pathogen’s PLD can regulate the polymerization and reorganization of its own actin filaments and induce the polymerization or reorganization of the host cell actin filaments near the foci, thus to promote the phagocytosis of the pathogen by host cell. Investigating the role of PLD activation in the infection will be significance for further understanding the molecular mechanism of pathogen-host cell interaction.

Abstract:Nitrite oxidoreductase (NXR) is the key enzyme responsible for the oxidation of NO2- to NO3- in nitrite-oxidizing bacteria. Since NXR is a dissoluble enzyme, located at the inner side of the membranes of cells, its function is dependent on the electron transfer chain related to membranes. This paper reviews the advances in study on NXR, including the structure, catalysis mechanism and the impact of different factors. New techniques applied in recent studies and research prospects are also presented.

Abstract:The spermosphere as an important habitat in plant micro-ecosystem is rich in temporal succession of microbial communities form and function. The indigeous and inoculated microbial community diversity, proliferation and activity could be regulated by the temporal succession and exudation of germinating seed exudates. The microbial chemotaxis in spermosphere is essential for their colonization , antagonistic activity to pathogens and bio-control of plant diseases. It shoud be assured that all the determination carried out are within the ephemeral time frame of germinating seed exudation and microbial activity with the unique experimental conditions in studies on the spermosphere micro-ecology. And some new insights would be proposed for the origin of microbes in rhizosphere and the reasonable application of benificial microbial inoculants in further investigation with the culture-independent as well as culture-dependent approaches in this area.

Abstract:Bioprocess equipment is of great importance in application of modern industrial biotechnology. With the rapid development of industrial biotechnology, demands for talents capable of understanding the theory, design and manipulation of modern bioprocess equipment increased. The experiences in aspects such as the building of teachers' contingent, construction of teaching materials, innovation of teaching method from the top-quality course construction of Bioprocess Equipment was discussed in this paper.

Abstract:A new teaching method was developed in the curriculum of Harmful Microorganisms Control Technology. It is characterized by students’ self-learning followed by student’s instruction. Both students and teacher have succeeded in this model after four stages of practice, in which a pleasant learning atmosphere was created in the classroom. An effective interaction between teacher and students was achieved. Students are viewed as main objects in the classroom and they are encouraged to ask questions, to formulate their own ideas, or to find things out for themselves. Thus, students’ abilities including presentation, communication, competition, and cooperation were enhanced. By adapting their role to the new teaching method, teachers have also improved their teaching skill and strategies.

Abstract:It is a trend that innovate the traditional bilingual education model and select a new teaching model. Code-switching is a lingual phenomenon when a passages or articles are expressed with two or more language. To guarantee effect of bilingual education and improve education quality, penetration bilingual education was applied during microbiology teaching. Professional English vocabulary, words, passages or articles were introduced to students timely and by measure by the way of language code-switching. The results showed that bilingual teaching mode with language code-switching inspire study emotion and self-confidence of English expression from students.

Abstract:The astaxanthin-hyperproducing mutants of oceanic red yeast were efficiently screened with β-ionone. As shown by the result, the biomass and astaxanthin content of oceanic red yeast was reduced due to the presence of β-ionone which inhibited the synthesis of carotenoids. The lethality rate of oceanic red yeast would attained 92.3% if 370 mg/L of the β-ionone concentration was contained in the plate medium. The oceanic red yeast mutated by ethyl methane sulfonate was cultured on plate medium containing 370 mg/L of the β-ionone. 200 mutants were randomly screened, positive mutants with increased the biomass, astaxanthin volumetric yield and astaxanthin specific yield accounted for 18% of the total strain, the mutants with higher biomass, astaxanthin volumetric yield and astaxanthin specific yield higher occupied 22.5%, 45% and 46%, respectively. The results indicated that the astaxanthin-hyperproducing strains of oceanic red yeast could be efficiently isolated on the selective medium containing β-ionone.

Abstract:In order to investigate the application potential of electrolyzed oxidizing seawater in reducing bacteria contamination, antibacterial effects of electrolyzed oxidizing (EO) seawater against harmful bacteria in suspensions and on food processing surfaces were studied in this paper. EO seawater was prepared from seawater and diluted seawater with tap water after electrolysis for 7 and 15 minutes. Bacteria suspensions including Escherichia coli O157:H7 (4.8×108 CFU/mL), Salmonella enteritidis (8.4×107 CFU/mL), Listeria monocytogenes(7.8×107 CFU/mL), Morganlla morganii (6.6×107 CFU/mL) and Vibrio parahaemolyticus (2.0×107 CFU/mL) were individually treated with EO seawater. The populations of all bacteria cells in suspensions were reduced hardly to zero after EO seawater treatment for 1min. Chips of stainless steel sheet, ceramic tile, floor tile, cleaning towels and gloves were inoculated with the bacteria and soaked in EO seawater for 5 min. Viable cells of bacteria were detected on all food processing surfaces after being hold at room temperature. Treatment of EO seawater reduced food-borne pathogens to undetectable level on stainless steel sheet, ceramic tile and floor tile. The results suggest that EO seawater be an ideal disinfection agent and used for decontamination of harmful bacteria on food processing surfaces.

Abstract:Six DNA extraction methods and four DNA purification methods were compared and analyzed in this study to get higher quality DNA from the rhizospheric soil of Fritillaria thunbergii Miq. Results showed that higher purity DNA were harvested by pretreating the soil with 20 mmol/L EDTA (pH 7.5), then isolating soil DNA with CTAB-SDS-frozen-thawing, and further purified by agarose method. The recovery rate of this soil DNA was about 44.00 μg/g ± 2.65 μg/g soil, and they were qualified for the microbial diversity analysis in the rhizospheric soil of F. thunbergii Miq based on the 16S rDNA sequence.

Abstract:To identify the 16S-23S rRNA gene in Enterobacter sakazakiis, a PCR-DHPLC assay was performed in this study. Primers specific for the 16S-23S rRNA gene of Enterobacter sakazakii in food were selected to conduct the DHPLC assays. The specific testing was performed with Enterobacter sakazakii and 59 strains, and various grads of Enterobacter sakazakii was used for the sensitivity testing. The good specificity was found in the study. Also, the method showed nicer sensitivity with the lowest amount of detecting was 181 CFU/mL, so it can detect and identify Enterobacter sakazakii quickly and correctly. The DHPLC could be a new method for detecting food pathogens.