Abstract:[Objective] To produce and characterize metallothionein in Cordyceps hawkesii mycelia under the zinc ion stress. [Methods] C. hawkesii achieved maximum mycelia of 12.2 g/L in a fermenter as Zn2+ up to 18 g/L. Pure C. hawkesii mycelia Zn-metallothionein was obtained with Sephadex G-50 and desalting Sephadex G-25 gel filtration, dried by freeze-drying. The methods of bradford and silver saturation with atomic absorption spectrometry analysis were used to separately determine the protein content and MT content. The methods of Ellman’s reagent colorimetry and atomic flame absorption spectrometry were used to determine the sulfhydryl content and the number of zinc atoms, respectively. The molecular weight of C. hawkesii mycelia Zn-metallothionein was determined by electron spray mass spectrometry (ESMS). Automatic amino acid analyzer measured amino acid composition. The antioxidant activity was identified by scavenging capacity of hydroxyl radicals, DPPH radicals and superoxide anion radicals. [Results] The Zn-metallothionein reached 15.3 mg/g mycelium (wet weight) after 64 h of fermentation. The molecular weight of Zn-metallothionein was 7 680 Da. One molecule Zn-metallothionein contained 18 mercapto groups and combined 4 zinc atoms. Amino acid composition analysis shows that each molecule of the protein contained 60 molecules of amino acids, which contained 15 molecules of cysteine, and contained three molecules of histidine and one molecule of aromatic amino acid. The antioxidant activity was slightly stronger than glutathione and weaker than mammal metallothionein. [Conclusion] C. hawkesii can synthesize Zn-metallothionein under Zn2+ stress and the structure was similar to mammalian metallothioneins.

Abstract:[Objective] The aim of the present study was to optimize the production process technique of microcapsules of Bacillus amyloliquefaciens against sturgeon-pathogenic Aeromonas hydrophila, and to observe their characteristics. [Methods] Based on the use of gelatin as the wall materials, the influences of gelatin concentration, inlet temperature, feeding speed and air flow on the viable cells in B. amyloliquefaciens microcapsules were assayed using single factor method, the spray drying processing parameters of its microcapsules were optimized through orthogonal experimental design, and their morphology and tolerance to artificial gastric and intestinal juices were further examined. [Results] The experimental results showed that the optimum spray drying processing parameters to prepare B. amyloliquefaciens microcapsules were gelatin concentration of 3%, inlet temperature of 155 °C, feeding speed of 8 mL/min and air flow of 700 L/h, and the most leading influence factor on the production of B. amyloliquefaciens microcapsules was the gelatin concentration, followed by feeding speed, air flow and inlet temperature. In addition, B. amyloliquefaciens microcapsules were spherical, featured dimpled surface without holes and cracks, uniformly-distributed with an average size of 9.22 μm. They were also found to have good tolerance to artificial gastric and intestinal juices, and exhibited a good inhibitory effect on the growth of sturgeon Aeromonas hydrophila. [Conclusion] The present study laid a good foundation for the industrial production of B. amyloliquefaciens microcapsules.

Abstract:[Objective] To increase the yield of L-malic acid and the utilization rate of xylose, the Aspergillus parasiticus CICC40365 was used as the strain to produce L-malic acid with xylose, and the fermentation technology in shake flask was investigated in the work. [Methods] The medium components and fermentation conditions were optimized through single factor experiments and response surface methodology. [Results] The optimal medium components were as follows: the xylose, (NH4)2SO4, yeast extract powder, MgSO4, MnSO4·H2O, FeSO4·7H2O and CaCO3 were 100.0, 2.0, 3.0, 0.20, 0.15, 0.08 and 80.00 g/L, respectively. The yield of malic acid from the optimal condition was 53.58 g/L and it was 40.5% higher than that of original condition. The reasonable fermentation conditions were inoculum ratio 8% (V/V), the liquid volume in the shake flask 60 mL/250 mL, fermentation temperature 32 °C, rotation speed 170 r/min, leading to the 55.47 g/L yield of L-malic acid. Meanwhile, the effect of Mg2+, Mn2+ on the relative enzymes in the xylose metabolism indicated that the xylulokinase played an important role in the process of xylose metabolism. [Conclusion] The xylose can be better utilized to produce L-malic acid through fermentation with Aspergillus parasiticus CICC40365, and the yield of L-malic acid and utilization rate of xylose were improved effectively through this experiment.

Abstract:[Objective] To develop efficient anaerobic treatment of wastewater from lignocellulosic bioethanol production, a laboratory-scale thermophilic anaerobic digestion in a fluidized bed reactor with activated carbon was developed. [Methods] After gradient domestication for 65 days, the operating parameters of the reactor have been optimized and dominant bacteria of the thermophilic anaerobic sludge were investigated based on 16S rRNA. [Results] The COD removal rate of 90% and methane yield of 290 mL/g COD were obtained at 55±1 °C, organic loading rate (OLR) of 13.8 g COD/(L?d) and hydraulic retention time (HRT) of 48 h in the anaerobic fluidized bed reactor (AFBR). The identification and analysis of bacteria showed that Clostridia accounts for the largest proportion of all microorganism and methanogen were dominated by Methanoculleus and Methanosarcina in thermophilic anaerobic sludge. [Conclusion] Bioethanol distilled wastewater can be degraded efficiently by abundant microbial species with methane production in AFBR.

Abstract:[Objective] We developed a rapid SYBR Green I fluorescent quantitative real-time PCR technique for detection of methane-oxidizing bacteria for microbial prospection of oil and gas. [Methods] The recombinant plasmid containing pmoA gene was used as standards to optimize the experimental conditions and generate a standard curve. The sensitivity, reproducibility and specificity of the technique were evaluated, and practical soil samples were detected using the technique. [Results] The correlation coefficient (R2) of the standard curve was 0.999 9 and the amplification efficiency was 99.976%. The detection range was from 3.897×101 to 3.897×109 copies/μL and the sensitivity was about 40 copies/μL. All variable coefficients of CT values in the reproducibility test were better than 3%. In addition, no amplification was observed in the templates of 12 non-methane-oxidizing bacteria. The technique showed good sensitivity, specificity and reproducibility. Soil samples collected in the gas field, the oil field and the non-oil and gas field were detected using the technique, and the gas field had high anomalies of methane-oxidizing bacteria. [Conclusion] The fluorescence quantitative real-time PCR technique developed here could rapidly and exactly detect methane-oxidizing bacteria for oil and gas exploration. At the same time, this technique could contribute to detection of other indicator bacteria in oil and gas field soil.

Abstract:[Objective] To investigate the planktonic bacterial community structure in Lake ULanSuHai and reveal its response to eutrophic factors. [Methods] DNA of total planktonic bacteria was extracted and used as template in the PCR amplification with bacterial universal primer pair 63F/1387R, and then PCR products were subjected to constructing 16S rRNA gene clone libraries of 3 different eutrophication level lake area, XK, HGB and SJB. Canonical correlation analysis (CCA) assay was applied to reveal the responses of bacterial community to eutrophication. [Results] The highest eutrophication level lake area-HGB has the highest diversity, richness and evenness, whereas XK of lowest eutrophication has the lowest diversity indexes. Proteobacteria, bacteroidetes and actinobacteria were dominant bacterial groups in Lake ULanSuHai. Abundances of α-, γ-, δ- proteobacteria, actinobacteria and bacteroidetes were varied greatly with the shifts of eutrophic levels. A lot of functional microbes with the probable ability degrading pollutants and cycling biogenic elements were detected in all sampled lake areas. Moreover, CCA analysis suggested that TN, NH4+, NO3? and COD had the most influence on planktonic bacterial community composition. Besides, there were plenty of unknown groups in Lake ULanSuHai. Some slightly alkaphilic and halotolerent bacteria were detected and they accounted for 9.6% of total bacteria in Lake ULanSuHai. [Conclusion] The diversity of planktonic bacteria is high in Lake ULanSuHai, and the community structure is complex and its composition is closely correlated with the eutrophic level of the lake waterbody.

Abstract:[Objective] Xylose fermentation is crucial in lignocellulosic ethanol production. Acetic acid generated during pretreatment process seriously inhibits xylose fermentation of yeast strain. The effect of differential expression of transaldolase gene (TAL1), one key gene in oxidative pentose phosphate pathway (PPP), on xylose utilization as well as acetic acid tolerance of genetically engineered xylose-fermenting strain NAPX37 was studied. [Methods] The promoter of TAL1 gene (PTAL1) of the strain NAPX37 was separately replaced with three promoters, PTDH3, PAHP1 and PUBI4, through homologous recombination. By subsequent sporulation, spore segregation and mating, three homozygotes in which PTAL1 were replaced with PTDH3, PAHP1 or PUBI4 were constructed. The fermentation capacity and acetic acid tolerance of the three homozygotes and the original strain NAPX37 were compared through batch fermentation using xylose or the mixture of glucose and xylose as carbon source. [Results] Three promoters, PTDH3, PAHP1 and PUBI4, increased the transcription level of TAL1 gene differentially, which not only improved xylose consumption rate and acetic acid tolerance significantly, but also improved glucose consumption rate under the condition of 60 mmol/L of acetic acid. When xylose was used as sole carbon source without acetic acid or when mixed sugar was used, the strain with PAHP1-controlled TAL1 gene showed better fermentation results than strains with PTDH3- or PUBI4-controlled TAL1 gene, indicating the expression level of PAHP1-controlled TAL1 gene was most appropriate. When xylose was used as sole carbon source under the condition of 30 mmol/L of acetic acid, the strain with PUBI4-controlled TAL1 gene showed best fermentation results among all strains, indicating the most suitable expression level of PUBI4-controlled TAL1 gene. [Conclusion] Three promoters, PTDH3, PAHP1 and PUBI4, overexpressed TAL1 gene, which improved xylose fermentation rate and acetic acid tolerance of strain NAPX37 differentially. However, the fermentation condition affected the level of improvement.

Abstract:[Objective] The seeds of Camptotheca acuminata Decne. containing camptothecin (an anticancer agent), was investigated to explore the endophytic actinomycetes diversity and screen for new active compounds producing strain. [Methods] The seeds of C. acuminata Decne. were sliced and plated on different selective media after surface sterilization. Colonies that looked like actinomycetes were selected, and identified according to the colonial morphology and 16S rRNA sequence analysis. Strains isolated were tested for antimicrobial activity using co-culture method. [Results] Thirty-three suspected endophytic actinomycetes strains were isolated from the C. acuminata Decne. seeds collected in campus of Shanghai Jiao Tong University. Among the suspected endophytic actinomycetes isolated, twenty-one were identified as Streptomyces, one was Nocardiopsis by 16S rRNA sequence analysis. Three endophytes were left to be determined due to low sequence similarity (less than 95%). The other eight strains were failed to be identified because of failure of their 16S rRNA sequence cloning. Further study was needed to determine whether or not these eleven strains were new actinomycetes species. Preliminary antibacterial and antifungal activity survey of strains isolated showed that approximately 42.42% of them can strongly inhibit the sclerotia formation of Rhizoctonia solani Kühn, and 54.54% of them can strongly inhibit the growth of Bacillus subtilis. Further, the metabolites of one representative strain—Streptomyces sp. CXSZ1 was studied and found to contain antibacterial compounds. [Conclusion] Study of isolation and identification of endophytic actinomycetes from the C. acuminata Decne. seeds and isolation of antimicrobial substances from the endophytic actinomycetes not only revealed the origination and evolution of endophytes in C. acuminata Decne. seeds, but also provided unique material for mining new structural and new bio-active compounds.

Abstract:[Objective] To investigate and discover some rare and important stilbellaceous entomogenous fungi from China. [Methods] The classical morphological and ecological characters were used for identification of specimens. [Results] A few Tilachlidiopsis specimen parasitic to coleopteran was identified as T. scarabaei L.S. Olive. The morphological characters of T. scarabaei were described as follows: Synnemata about 36 mm long, 1.8 mm wide, dark brown below, white above, sometimes branched, polycephalous. Phialides with palisade arrangement in a compact hymenium-like covering the heads, but terminal or lateral phialides occurring on the simple conidiophores in the stipe close to the heads, mostly conical, rarely clavate, and tapering toward the top, (19.4?25.9) μm×(1.1?2.2) μm. Conidia, mostly elliptical, (2.2?3.2) μm×(1.1?2.2) μm; subcylindric, (4.3?5.4) μm×(1.1?2.2) μm; rarely spherical, 1.1?2.2 μm. [Conclusion] The specimen is reported as T. scarabaei L.S. Olive, which is a new record species in China.

Abstract:[Objective] We evaluated the effect of inoculating Lactobacillus plantarum on the quality of small-scale forage paddy rice silage. [Methods] We analyzed the forage paddy rice inoculated with L. plantarum by comparing with the naturally fermented samples in sensory qualities, microflora and fermentation qualities (using V-Score evaluation method). [Results] L. plantarum was dominant, and harmful and pathogenic bacteria were inhibited in inoculated samples. [Conclusion] Inoculating L. plantarum can improve the qualities of silage, and they can be considered as starter culture for forage paddy rice silage.

Abstract:[Objective] Genetic diversity and relationship of the rhizobia isolated from Leucaena leucocephala in Panzhihua City of Sichuan were analyzed. [Methods] We studied genetic diversity of these isolates with combined RFLP patterns of 16S rDNA and IGS (16S-IGS RFLP), AFLP fingerprinting, and constructed 16S rDNA, atpD, recA gene phylogenetic trees and phylogenetic tree based on the concatenated sequences of the three genes. [Results] Fifteen distinct 16S-IGS genotypes and 27 AFLP genotypes were distinguished among the 31 isolates based on 16S-IGS RFLP and AFLP, respectively. In 16S-IGS RFLP dendrogram, all isolates were not clustered with Bradyrhizobium reference strains, but were grouped into three groups such as genus level required at similarity level of 71.4% for Sinorhizobium (28 isolates, S group), Mesorhizobium (2 isolates, M group), Rhizobium (1 isolate, R group). At similarity of 84%, 28 Sinorhizobium strains were divided into three, nine clusters in 16S-IGS RFLP, AFLP dendrograms, respectively. Analyses of multi-locus housekeeping genes of 16S rDNA, atpD and recA indicated representative strains SCAU215, SCAU231 were closely related to M. Plurifarium, R. huautlense, nevertheless SCAU222 and SCAU228, SCAU213, SCAU216 might represent three new Sinorhizobium groups. [Conclusion] The rhizobia isolated from L. leucocephala in Panzhihua City had rich genetic diversity, these isolates were assigned as Sinorhizobium, Mesorizobium and Rhizobium, and Sinorhizobium was the predominant genus.

Abstract:[Objective] To determine the presence and genetic diversity of Papaya ringspot virus (PRSV) in Yunnan province. [Methods] Twenty-four symptomatic samples of Carica papaya, Cucurbita moschata and Siraitia grosvenorii were collected from 9 regions of Yunnan province in 2011 and 2012, and tested the presence of PRSV by RT-PCR. The amplicons of 940-bp covering partial coat protein (CP) and 3′-untranslanted region (UTR) were cloned and sequenced. Pairwise comparisons and phylogenetic analysis were performed. [Results] PRSV was detected in 17 samples (70.8%), indicating the virus is common in Yunnan. Sequence analyses revealed the high genetic diversity among the isolates. [Conclusion] PRSV was detected in three different host crops in Yunnan province. Sequence analysis indicated a high genetic diversity among the isolates. Phylogenetic analyses indicated the existence of both PRSV groups, but further research is needed to reveal the correlation between molecular variations of PRSV and geographic regions or the symptoms PRSV causes.

Abstract:[Objective] The effects of photosynthetic bacteria on growth and photosynthetic function of wheat was researched. [Methods] Yaomai16 was employed as the research material of this research. Different kinds of photosynthetic bacteria were spread during different growth phase of wheat in order to investigate the effect of photosynthetic bacteria to the wheat in terms of growth, productivity and photosynthetic function. [Results] Different composition of culture medium of photosynthetic bacteria culture can improve the SPAD value of flag leaves, as well as photosynthetic reaction speed and dry-weight accumulation. After fertilized with photosynthetic bacteria during the elongation phase, the mixed bacteria has the largest promoting effect on the amount of SPAD in leaves, which is 33.6% higher than control groups without treatment of photosynthetic bacteria. Moreover, the dry weight accumulation and the seed weight of individual plant are increased for 25.7% and 14.3% respectively than control groups. Rhodopseudomonas palustris has the largest promoting effect which increases both the dry weight accumulation and the seed weight of individual plant for 13.1% respectively comparing to the diluted medium controls. The results from the treatment at different period indicate that Rhodopseudomonas palustris culture medium has the strongest promoting effect in jointing period and milk filling period. Additionally, the resting cell can extend the functional period of leaves and further continuously increase the photosynthetic product, the culture medium without cells can increase the productivity of wheat through improving the vegetative growth of wheat. [Conclusion] The photosynthetic bacteria can promote the growth and enhance the photosynthetic related function effectively during the developmental process of wheat. Jointing period and milk filling period are suggested to be the two of the best spread period. The increase of growth and productivity of wheat by photosynthetic bacteria is the integrated consequence of interaction between resting cell and active metabolites.

Abstract:[Objective] To identify and characterize a bacterial strain S1-2 isolated from the imported Trachurus japonicas and express the flagellin in Escherichia coli BL21. [Methods] The physiological and biochemical characteristics were elucidated by employing VITEK 2 compact automated microbiology system and Gram-positive identification card. Real-time PCR method aiming for the amplication of the iap gene was used to detect strain S1-2. The flaA gene from S1-2 was amplified by PCR and cloned into prokaryotic expression vector pET-22b. The recombinant product was purified by nickel affinity chromatography. Western blot was employed to test the immunogenicity. [Results] Strain S1-2 was identified as Gram-positive and exhibited the highest levels of 99% probability to be Listeria monocytogenes based on the conventional physiological test. An enhanced zone of β-haemolysis at the intersection of Staphyloccocus aureus was found. SDS-PAGE indicated that the molecular weight was about 32 kD. Western blot showed that the recombinant protein FlaA had immunogenicity. [Conclusion] These results would provide basis for the further studies on the development of monoclonal antibody against Listeria monocytogenes and the establishment of the detection methods.

Abstract:[objective] To identify and construct an infectious clone for an isolation of porcine circovirus type 2 (PCV2). [Methods] PCR was used to identify an isolate, PCV2 GD-zq strain, from the tissues of clinical pigs with postweaning multisystemic wasting syndrome (PMWS). The complete sequence of the isolate was megaligned with other 5 PCV2 Guangdong isolates (GD-pz, GD-gj, GD-jm, GD-ss and GD-sz) from GenBank by DNAstar. Two copies of the whole genomic sequence was amplified and cloned into pUC18 with the restriction enzymes EcoRⅠ, SalⅠ, SalⅠand Hind Ⅲ, and the positive clone pPCV2-2GD-zq was identified by enzyme analysis. By purification and quantitation, the pPCV2-2GD-zq DNA was transfected to PK-15 cell lines to rescue the infectious PCV2 GD-zq. [Results] PCV2 GD-zq strain was isolated and identified from the lymphonodus of clinical pigs with PMWS. Sequence analysis shows that the isolate’s complete genome was composed of 1 767 nucleotides, which shares 96.0%–99.6% homology between other 5 Guangdong reference strains, and shares 97.1%?99.7% homology in ORF1, 93.2%?99.6% in ORF2, respectively. Amino acid homology alignment shows 98.7%?100% in ORF1 and 93.2%?99.6% in OFR2. Seventy two hours post transfection of pPCV2-2GD-zq, GD-zq strain could be detected by immunofluorescence assay (IFA). [Conclusion] A PCV2 was isolated, and its infectious DNA clone was constructed successfully.

Abstract:Ubiquitination, as a regulating mechanism of cell reactions, exists extensively in plant and is involved in regulating plant disease resistance. This paper reviewed the function and mechanism of ubiquitination system in regulating plant disease resistance. Particularly, we mainly introduced how CRLs and RING/U-box type E3 ubiquitin ligases mediate plant disease resistance signaling and the molecular mechanism of regulation in plant disease resistance through effectors and virulent factors of pathogens. This paper provides reference for illustrating the mechanism of plant disease resistance and controlling the plant diseases.

Abstract:Marine environments harbor a large variety of microorganisms that play an important role in the ecological system, most of them are closely related with human life. So far, only less than 1% marine microorganisms have been cultured by conventional methods. This paper discusses the importance of marine microbes, the reasons why most of marine microorganisms cannot be cultivated and progress in high-throughput culturing and sorting methods of marine microorganisms. With further research, more practical and effective high-throughput culturing and sorting methods will emerge.

Abstract:Phosphopantetheinyl transferases (PPTases) play essential role in the biosynthesis of fatty acids, polyketides, and nonribosomal peptides. PPTases phosphopantetheinylate carrier proteins in polyketide synthases (PKSs), fatty acid synthases (FASs) and nonribosomal peptide synthetases (NRPSs). In this review, we discuss current studies on the substrate specificities of PPTases to carrier proteins in Streptomyces. The substrates of type Ⅲ PPTases are acyl carrier proteins (ACPs) which locate within the same PKSs. The favorite substrates of typeⅠ PPTases are ACPs in typeⅡ FASs and typeⅡ PKSs. The favorite substrates of typeⅡ PPTases are ACPs in typeⅠ PKSs and peptidyl carrier proteins (PCPs) in NRPSs. The favorite substrates of a typeⅠ/Ⅱ PPTase, whose encoding gene locates in a gene cluster, are ACPs/PCPs whose encoding genes locate in the same gene cluster.

Abstract:Abundant of microorganism colonized in the gastrointestinal tract. They constructed a mutually dependent and restrained micro-ecological environment with the host. The composition of gut microbiota was closely related with the gene, dietary, health state and environment of the host. Furthermore, the gut microbiota was regarded as a post natal acquired organ and they played important roles in nutrient absorption and digestion, energy supply, fat regulating, intestinal epithelium renewal stimulating and immune system directing. This review focused on the research advancement of some modern molecular biotechnology in intestine microorganism research, including fluorescence in situ hybridization (FISH), polymerasechain reaction denaturing gradient gel electrophoresis (PCR-DGGE), real-time polymerase chain reaction (RT-PCR), gene chip and pyrosequencing platform as the representative of the second generation sequencing technology. In additions, it also made a future prospect for the study of intestinal flora.

Abstract:A major group of obligate marine bacteria (designated MAR 1) within the order Actinomycetales has been discovered from tropical and sub-tropical ocean sediments, and was proposed to establish a novel genus Salinospora based on morphological, physiological, biochemical characteristics and 16S rRNA gene sequence analysis. The genus was validly published in 2005 and the name proposed for this novel taxon was corrected as Salinispora, which is the first obligate marine genus within the order Actinomycetales. Moreover, Salinispora is a rich source of novel biologically active secondary metabolites. In recent years, lots of research achievements on the genus Salinispora were reported. The objective of this review is to summarize the research advance, such as establish process of the genus, the taxonomic characteristics, physiological and ecological research, as well as recent studies in molecular biology and secondary metabolites in the genus Salinispora.

Abstract:Ballistosporous yeasts can catapult spores (called ballistospore), which consist of genera Bullera, Sporobolomyces and Sporidiobolus. They widely distribute in various environments. Ballistosporous yeasts mostly grow in the morphology of budding, ballistospore and mycelium in laboratory Sporidiobolus form the sexual spores by pairing. Owning to the development of molecular biology, the phylogenetic relationship between all kinds of ballistosporous yeasts become more clearly. This paper indicates that cell differentiation phenomenon exist in ballistosporous yeasts in combination with the research results in our lab, and conjectures cell differentiation would contribute to resist environmental stress. Consequently, ballistosporous yeast would be a potential model organism to explore mechanisms for stress resistance. Because the problems in food and environment are increasingly prominent, ballistosporous yeasts, which have ability to accumulate a large amount of useful metabolites (such as esters, pigments, enzymes) and also take part in environmental management, are paid more and more attention.

Abstract:Macrofungi are those fungi with large fruit bodies, and they are a rich source of foods and medicines. Many of them have significant antioxidant activity. The present review documented the chemical structures and antioxidant activity of the low-molecular-weight secondarymetabolites from macrofungi. The aim of this review is to help the researches on the activity screening, chemical analysis and exploitation and utilizing of macrofungi.

Abstract:The existing textbooks, with the contradiction between the expression on the formulation of influenza virus capsid and the general definition of virus capsid, has made both teachers and students confusing. Therefore, this article explores this issue, with a view to arousing the concern of textbook writers and users, and thus contributes to establish a relatively accurate concept and give a reasonable description.

Abstract:[Objective] To develop polyclonal antibody against MurA protein and combine immunomagnetic with selective plate to rapidly detect Listeria monocytogenes (LM). [Methods] Prokaryotic expression vector of MurA was constructed and transformed into E. coli to optimally express. Product after expression was purified by nickel affinity chromatography, mass spectrometry analysis was used to identify the recombinant protein; after correct identification, the protein was applied to immune mice in order to prepare polyclonal antibodies. The antibodies we acquired were used to develop immunomagnetic beads, which combined with selective medium to detect artificial contaminated milk samples. [Results] A soluble fusion protein with a molecular weight of 72 kD was expressed in E. coli, this protein was identified as MurA protein; antiserum possessed a titer as high as 10 000, with no cross-reaction to Salmonella typhi, Vibrio prholyticus, E. coli and other pathogenic bacteria. Despite a little cross reaction with Listeria innocua, the method combined specific immunomagnetic beads with selective medium managed to detect LM of a concentration of 103 CFU/mL or above. After nine hours enrichment, milk samples within an original concentration of more than 0.4 CFU/mL were successfully detected, which was 39 hours less than the regular enrichment method. [Conclusion] Recombinant MurA protein was highly expressed in E. coli and showed high purity after purification, the polyclonal antibodies showed high affinity and specificity against LM. The immunomagnetic beads-selective medium method for detecting LM was able to detect milk samples within 24 hours, which was 42 hours less than national standard method with the same sensitivity.

Abstract:

Abstract:[Objective] The purpose of this project was to isolate a newly formaldehyde-degrading bacterium from soil of dyeing and printing plant activated sludges. [Methods] Strain was isolated by pure culture method and classified based on standard morphological identification, physiological and biochemical tests, 16S rRNA gene sequence analysis and formaldehyde dehydrogenase genes amplification. And the orthogonal design was used to study the capability of degradation characteristics of strains W1. [Results] The strain was identified as Pseudomonas putida. The optimum conditions of formaldehyde degradation were as follows: concentration of formaldehyde 500 mg/L, incubation temperature of 30 °C, pH 6.0, rotating rate of 200 r/min, bottled fluid volume of 3%. [Conclusion] The results showed that under optimum conditions, strain W1 had strong formaldehyde degradation capability in this study. The removal efficiency of formaldehyde can be as high as 98% in 24 h.

Abstract: