Abstract:

Abstract:[Objective] 3-HP is an important bio-based platform compound. We wanted to isolate a strain which can produce 3-HP. [Methods] We isolated samples of soil(17) and feces(10) and did physiological-biochemical identification and 18S rDNA sequence analysis with Y-11 .Then we used UV-NTG-60Coγ to generate mutations. [Results] A yeast Y-11 which can use propionic acid to produce 3-HP was screened by us. It was identified as Candida sp.. We used UV-NTG-60Coγ to generate mutations in Y-11 and got a genetic stability mutant, designated as 5-13B. The mutant 5-13B showed the productivity of 3-hydroxypropionic acid is 11.78 g/L, 2.46 times as that of the primitive strain(Y-11). [Conclusion] The fermentation characters of primitive strain and mutant strain were compared. The results showed that the consumption rate of propionic acid, accumulation of 3-hydroxypropionic acid and tolerance of propionic acid of mutant strain are better than primitive strain.

Abstract:

Abstract:[Objective] In order to optimize precursor supply for L-valine biosynthesis, a Corynebacterium glutamicum V1 mutant with phosphoenolpyruvate carboxylase gene (pepc) in-frame deletion was constructed through crossover PCR and homologous recombination. The effect of pepc knock-out on physiological characteristics of the mutant was investigated. [Methods] The upstream and downstream fragments of pepc were cloned from C. glutamicum V1 chromosome and ligated to integration vector. The mutant C. glutamicum V1-Δpepc was screened by homologous recombination. The physiological characteristics of the mutant were investigated by fermentation experiments and enzymes activity measurement of pyruvate carboxylase (PC), pyruvate dehydrogenase (PDH) and pyruvate kinase (PK). The mutant with pepc gene in-frame deletion was screened and confirmed by PCR and phosphoenolpyruvate carboxylase activity determination. [Results] The pepc knock-out resulted in L-argine accumulation to 7.48 g/L and no accumulation of L-valine, which accompanied by increase of PDH activity and PC activity in C. glutamicum V1-Δpepc. The knock-out of pepc gene affected the metabolism of the strain to some extent. [Conclusion] Blocking the anaplerotic pathway PEPC participated increased TCA cycle, leading to the increase of L-argine and decrease of amino acids with pyruvic acid as precursor , such as L-valine and alanine.

Abstract:[Objective] The utilization of using mariculture organic waste for anaerobic hydrogen fermentation could reduce organic pollutant and obtaining clean energy hydrogen simultaneously. [Methods] We used mariculture organic waste for hydrogen production, and investigated the effect of different pretreated methods of, solubilization by thermophilic enzyme (S-TE), acid, alkaline, sterilized, and microwave on mariculture organic waste hydrogen production. The efficiency of these pretreatments and profiles of SCOD, soluble protein and carbohydrate, pH value, VFAs and ethanol during the fermentation were also monitored. [Results] The maximum hydrogen yield was 22.0 mL/g VSS, which was obtained from sterilized pretreatment, whereas the minimum hydrogen yield of 7.6 mL/g VSS was obtained from acid pretreatment. The fermentation stopped after soluble carbohydrate was largely consumed. More nutrients could be released from mariculture organic waste after S-TE pretreatment than other pretreatments, and the pH value was remained stable during the fermentation. The main composition of VFAs was acetic acid, and ethanol was produced at the end of fermentation. [Conclusion] Sterilized pretreatment was the optimum pretreatment method of anaerobic hydrogen fermentation from mariculture organic waste, and soluble carbohydrate was the main nutrient resource during the fermentation.

Abstract:[Objective] The objective was to study the identification, degradation characteristics and the degradation pathway of the atrazine-degrading strain DNS32, and enrich the resources of atrazine-degrading bacteria. [Methods] Strain DNS32, which was isolated from black soil in this study, could utilize atrazine as the sole nitrogen source for growth, and its basic degradation characteristics were studied. The 16S rRNA gene phylogenetic analysis was used to identify of the strain DNS32. The degradation pathway was studied by degrading genes amplification and the measurement of the content of the final catabolite. [Results] The results showed that strain DNS32 had greater degradation capacity and could utilize certain amount of atrazine even under a relative low temperature. The 16S rRNA gene phylogenetic analysis showed that the 16S rRNA gene sequence of the strain DNS32 had a 99% similarity with that of Acinetobacter lwoffii. Atrazine-degrading genes trzN, atzB and atzC were amplified by PCR, and these genes enabled strain DNS32 decompose atrazine to cyanuric acid, in accordance with the degradation pathway of Arthrobacter aurescens TC1 proved by the measurement of the atrazine degradation rate and the content of the final catabolite. [Conclusion] This study enriched the resources of atrazine-degrading bacteria and provided useful informations to the study of the atrazine-degrading strains belonging to Acinetobacter.

Abstract:[Objective] Resistant strains have become increasingly prominent issues, and the development of safe and efficient antimicrobial agents becomes the focus one of researches so far. Antimicrobial peptides possess many attractive features. Exploration and recombinant expression of antimicrobial peptides with high activity have important significance for solving resistant strains problem. [Methods] A novel hybrid antimicrobial peptide LfcinB-Cecropin was designed based on the structures of LfcinB and Cecropin. The gene encoding LfcinB-Cecropin was synthesized according to codon preference of E. coli. Tandem expression plasmids contained multicopy tandem LfcinB-Cecropin genes were constructed by the method of isocaudarner, and expressed them in E. coli. [Results] LfcinB-Cecropin was successfully expressed as fusion protein by IPTG induction. After sonication, inclusion body purification, formic acid cleavage, the recombinant LfcinB-Cecropin was obtained and showed obvious antibacterial activity. [Conclusion] A novel antimicrobial peptide LfcinB-Cecropin was obtained and recombinantly expressed in E. coli in high level.

Abstract:[Objective] In order to understand the relationship between endophytic bacterial diversity of banana and fusarium wilt disease, thus providing a scientific basis for the biological control against fusarium wilt. [Methods] Endophytic bacterial diversity and communities of different plant tissues of two banana cultivars with different resistance to fusarium wilt were examined using Terminal Restriction Fragment Length Polymorphism (T-RFLP). [Results] The results indicated that resistant cultivar “Nongke No.1” showed more abundant endophytic bacterial diversity than that of susceptible cultivar “Brazil” in the root, pseudomeristem and leaves of plants. Diseased plants conserved more abundant endophytic bacterial diversity than that of healthy plants in different tissues. Endophytic bacterial diversity of “Nongke No.1” kept basically stabilized, but that of “Brazil” showed a great range of variation among healthy and different diseased stages. Dominant bacterial populations were various in the different tissues, and there were some specific dominant populations in the healthy and diseased banana plants of different cultivars. [Conclusion] The results indicated that resistant cultivar showed more abundant and steady endophytic bacterial diversity than that of susceptible cultivar. Diseased plants showed more abundant endophytic bacterial diversity than healthy plants. In addition, there is a marked diversity of dominant populations in different plants between resistant or susceptible cultivars to fusarium wilt disease.

Abstract:[Objective] Citrus (Citri) is an economically important fruit crop in the world. The anthracnose caused by Colletotrichum gloeosporioides (Penz.) Sacc. is one of the main diseases in citrus production. For exploring of an effective biocontrol measure against citrus postharvest anthracnose, a bacterial biocontrol strain T132 isolated from the rhizosphere soil of citrus was identified and characterized. The efficacy of the biocontrol strain against citrus postharvest anthracnose disease was evaluated. [Methods] Identification of strain T132 was carried out by using 16S rDNA sequence homology comparison as well as morphological, physiological and biochemical characteristics. The antagonistic stability of the strain T132 was determined by continuously transferring it on artificial media for 8 generations. The efficacy of strain T132 in controlling citrus postharvest anthracnose was performed by stab inoculation and naturally infected methods. The use of specific primers detect the strain T132 of the pathogenic factor of Burkholderia cepacia as a potential human pathogens. [Results] Strain T132 was identified as Burkholderia vietnamiensis based on its morphological traits, phyiological and biochemical characters as well as 16S rDNA sequence analysis. Less change in the suppressive ability of antagonizing against growth of C. gloeosporioides was observed during 8 generations of transfers on artificial media. The strain T132 had significant efficacy in controlling citrus anthracnose disease causing by C. gloeosporioides. The average efficacies of the strain T132 in controlling the disease were 88.2% in artificial inoculation test and 54.9% in natural infection test 20 d and 60 d after of the antangonist applications, respectively. It was no virulence gene of Burkholderia cepacia epidemic strain marker (BCESM) existed. [Conclusion] This is the first report of B. vietnamiensis as a biocontrol agent against citrus postharvest anthracnose disease and the relative safety of biocontrol strains on human.

Abstract:[Objective] This work aimed to explore yeast community structure and ecological diversity in making process of Chinese light-style liquor, which would be benificial for scientifically understanding of the formation mechanism of Chinese light-style liquor. [Methods] Yeast variety and quantity during making process of Chinese light-style liquor was investigated by WL medium and 26S rRNA D1/D2 region sequence analysis. [Results] Ten yeast species were identified as Saccharomyces cerevisiae, Issatchenkia orientalis, Pichia anomala, Saccharomycopsis fibuligera, Pichia fermentans, Trichosporon asahii, Hanseniaspora osmophila, Pichia farinosa, Pichia membranifaciens and Clavispora lusitaniae. Among them, T. asahii, P. membranifaciens, H. osmophila, P. farinose and P. fermentans were firstly isolated in Chinese light-style liquor. Athough the quantity of S. fibuligera dominated in three types of Daqu, yeasts ecological distribution was different. There were the most amount and varieties of yeast species in Daqu of Qincha. Yeast community structure of fermented grain was also different from that of Daqu and difference also existed between fermented grain of Dacha and Ercha. S. cerevisiae was dominant at later stage of liquor fermentation, while the dominant species in Dacha and Ercha were H. osmophila and P. membranifaciens at early stage, respectively. [Conclusion] This work deeply studied the yeast distribution characteristics and community structure in making process of Chinese light-style liquor, which would show great value in scientifically understanding of the formation mechanism of Chinese light-style liquor.

Abstract:[Objective] The aim of the present study was to isolate and identify the pathogen of Pelteobagrus fulvidraco egg saprolegniasis, and study the drug susceptibility characteristics of the pathogen. [Methods] Filamentous fungal strains were first isolated using the traditional method from the Pelteobagrus fulvidraco eggs suffering from saprolegniasis, and the pathogenic strain was further confirmed through artificial infection experiment, identified using morphological observation and phylogenetic analysis based on its ITS rDNA sequence. In addition, its drug susceptibility was studied using the doubling dilution method. [Results] Eight filamentous fungal strains were isolated form Pelteobagrus fulvidraco eggs with saprolegniasis, and strain YC was proved to be pathogenic to Pelteobagrus fulvidraco eggs by artificial infection. Thus, morphological characterizations of strain YC were studied, the phylogenetic analysis based on its ITS rDNA sequence and drug susceptibility assay were also further conducted. The experimental results showed that the hyphae of strain YC were aseptate and transparent, its zoosporangia were cylindrical, clavate or fusiform, its zoospores were discharged from the tip of zoosporangia, clumped together and fell off or directly swam into the water after a period of time. The zoosporangia were renewed in basipetalous succession, infrequently in sympodial arrangement. Its oogonia were spherical or obpyriform with frequently diclinous and occasionally monoclinous antheridial branches, and produced one to fifteen oospores, which were centric or subcentric, and laterally generated a big oil body. The ITS rDNA sequences of strain YC was naturally clustered with ITS rDNA sequences of Achlya sp. submitted to GenBank with the homology of 99%, and had closest relationship with Achlya klebsiana strain CBS101.49 (GenBank accession numberAF119579). Combined the morphological characterization with phylogenetic analysis based on ITS rDNA sequence, strain YC was identified as Achlya klebsiana. In addition, strain YC was well inhibited by Coptis chinensis and isothiazolinone, whose minimum inhibitory concentrations to strain YC were respectively 256 mg/L and 2 mg/L. [Conclusion] A pathogenic Achlya klebsiana strain YC was isolated for the first time from Pelteobagrus fulvidraco eggs suffering from saprolegniasis, and its drug susceptibility was also determined, which could serve as a foundation for its infection in Pelteobagrus fulvidraco eggs.

Abstract:[Objective] Pseudomonas aeruginosa is a typical opportunistic pathogen which often causes serious and persistent infections in hospitals. As antibiotics have been used extensively and constantly, P. aeruginosa developing higher multi-drug resistance. Hence, investigating the mechanisms of antibiotic resistance in P. aeruginosa has significant clinical value. [Methods] A clinical isolated strain PA68 was adopted to construct a Mu transposon insertion mutant library. One mutant strain named M122 with abnormally high streptomycin resistance was isolated from the library. Southern blotting confirmed that the insertions had occurred as single event. DNA microarray was used to analyze the genomic expression in M122. [Results] Gene cloning and sequencing indicated that the alteration of M122 phenotype was due to the insertional activation of a novel gene PA0058. Mutation of PA0058 gene resulted in a higher resistance to several kinds of aminoglycoside antibiotics. After transforming a plasmid containing gene PA0058 into M122, the resistance phenotype restored partially. To exclude the strain specific, gene PA0058 was knocked-out in P. aeruginosia PAK. The results indicated that the mutation of gene PA0058 causes multiple gene expression change in P. aeruginosa, especially the significantly up-regulated antioxidant enzyme genes. [Conclusion] This is the first time the gene PA0058 was identified and reported to be involved in upward aminoglycoside resistance in P. aeruginosa.

Abstract:[Objective] In this study, we investigated the influence of HSV-2 2.2 kb latency associated transcript on the growth characteristics of Hela cells in vitro. [Methods] We observed the growth of Hela cells transfected with recombinant expression plasmids pcDNA3.1-2.2 kb LAT along with pcDNA3.1 control. In 4 °C or 43.5 °C, vitality of cells and apoptosis rate of cells was detected by MTT and Hoechst33258 staining. [Results] The transcription of 2.2 kb LAT was detected in Hela cells transfected with pcDNA3.1-2.2 kb LAT. The number of cells transfected with pcDNA3.1-2.2 kb LAT was higher than that transfected with pcDNA3.1 (1.7±0.09×105/mL and 1.45±0.14×105/mL, respectively, P<0.05) at 2 days. The apoptosis rate of cells transfected with pcDNA3.1-2.2 kb LAT was lower than that transfected with pcDNA3.1 (27.6%±5.7%和7.8%±1.5%, respectively, P<0.01) at 4 °C. The apoptosis rate of cells transfected with pcDNA3.1-2.2 kb LAT was lower than that transfected with pcDNA3.1 (30.5%±4.6%和5.3%±2.0%, respectively, P<0.01) at 43.5 °C. [Conclusion] The Hela cells transfected with pcDNA3.1-2.2 kb LAT showed promoted proliferation, heightened vitality and reduced apoptosis. These experiments demonstrated that 2.2 kb LAT could play an important role in HSV-2 infection.

Abstract:Pathogens is a major cause of gastrointestinal illness and hazardous to human health. Application of probiotics to the prevention of pathogen infection has received much attention due to safety and decreasing drugtolerance. Here we summarize the recent progress in mechanism of probiotic bacteria inhibition of pathogens including competition for adhesion sites with pathogens, coaggregation with pathogens and production of antimicrobial substances.

Abstract:Isomaltulose as a functional isomer of sucrose has attracted much more attention in the industrial application due to its attractive features such as non-cariogenic, prebiotic and diabetics-acceptable nutrient and resistance to most bacteria and yeasts. It has been proved that sucrose isomerase not only transforms sucrose to isomaltulose and trehalulose, but also produce a small amount of glucose and fructose as by-products, which is a considerable industrial problem because elaborate purification are necessary to remove them. In this paper, we discuss the characteristics and functions of isomaltulose as well as potential problems in its production. Particularly, we focus on the catalytic mechanism of sucrose conversion by sucrose isomerase, which is in favour of developing isomaltulose in the application of foodstuff.

Abstract:In this communication, the construction of web-based laboratory for the improvement of microbial teaching and management was discussed. It was found that web-based laboratory can help students to be familiar with experiments and alter the situation that laboratory condition is limited. In addition, the simulated experiments on web-based laboratory platform can offset the deficiencies existing in traditional experimental teaching. Besides, it can be used to not only expand students’ experimental skills, but also effectively strength the process management of graduation and improve the advice efficiency. Moreover, this platform can contribute to the improvement of the operation efficiency of real laboratory. Last but not the least, this web-based laboratory can be used to display students’ experimental results and their study achievements, thereby promoting them for success.

Abstract:In order to improve the microbiological experiment skill of the students, through experimental teaching research, the microbiology experimental teaching in higher vocational education reform discussion. Experimental design of logical coherence, strengthening basic experiment teaching and the creation of comprehensive experiments enhance experimental skills training. Creative experimental teaching methods, using multimedia displays, enhance practical ability of speaking practice fusion. Implementation of fitness exercises, strengthen the experimental process guidance and strictly regulate the operation, establish a better comprehensive assessment mechanisms to mobilize students' enthusiasm and initiative of the experiment to enhance experimental skills upgrading and improve the quality of teaching.

Abstract:[Objective] To explore an effective method for accurately getting fungal strain isolates from the genus Psilocybe and Panaeolus. [Methods] Twenty-eight freshly collected fruit bodies were used as study materials. The cultures isolated from gill and basdiospores were identified based on morphology and sequence of ITS rDNA. [Results] Twenty-four isolates (86%) were purified successfully by gill inoculation method and seven (25%) by basidiospore discharge. [Conclusion] Gill is the spore-bearing tissue of agarics, and easy to germinate. Furthermore it is no need to sterilize the surface of the gill for purification in culture medium. This isolation approach may be extended in other groups of the saprophytic fungi characterized by small fruiting body size and thin pileus, similar to these two genera.

Abstract:[Objective] In order to construct dysbacteriotic mice model of diarrhea and understand the curative effect of ultra-micro Qiweibaizhusan. [Methods] The dysbacteriotic mice models were constructed by using traditional Chinese medicine compound and combination antibiotics to cause diarrhea, and then treated with ultra-micro powder of Qiweibaizhusan. [Results] Traditional Chinese medicine dachengqitang had quick effect on diarrhea. The symptom of insufficiency of the spleen would appeared in mice with long time traditional Chinese medicine dachengqitang treatment. But it had low effect on intestinal microbes (P>0.05). The combining using of gentamycin sulfate and cefradine had the best effect on diarrhea. After treated with ultra-micro powder Qiweibaizhusan, traditional Chinese medicine dachengqitang group were cured quickly and the symptom of insufficiency of the spleen disappeared. The quantities of intestinal lactobacillus and fungus in antibiotic group were much higher than the normal group (P<0.01). [Conclusion] A dysbacteriotic mice modeling method of diarrhea was constructed. There were some kinds of probiotics contained in ultra-micro powder Qiweibaizhusan which could promote the growth of intestinal lactobacillus and fungus.

Abstract:[Objective] To confirm the detecting property of TEMPO/TVC method in foods. [Methods] TEMPO/TVC method compared with national food safety standard GB4789.2 aerobic plate count method in foods, including cooked meat products, convenience food, quick-frozen food, puffed food, candy, pastry, condiment. [Results] The results of TEMPO/TVC method and national food safety standard method showed good agreement; and the P value was greater than 0.05, no significance difference between the two methods. [Conclusion] TEMPO/TVC method is a rapid and accurate method, worthy of promoting in routine examination.