Abstract:

Abstract:Escherichia coli trpBA-encoded tryptophan synthetase (TSase) and serA-encoded D-3-pho- sphoglycerate dehydrogenase (PGDH) are key enzymes in tryptophan and serine biosynthesis pathway, respectively. In order to improve bio-production of tryptophan through bioengineering means, a feedback inhibition resistant serA gene was cloned by PCR and co-expressed with trpBA gene, which was cloned and expressed before. Four recombinant plasmids were constructed successfully in the recombinant strains. SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis) showed target protein products of 37 kD (PGDH), 29 kD (TSase α subunit), 44 kD (TSase β subunit). The enzyme activity analysis indicated the specific activities of TSase was increased by 2~4-fold, and that of PGDH was increased by 2.1~3.6-fold, compared to the control. High enzyme activities could lead to high tryptophan production by the shake flask fermentation. The amount of tryptophan biosynthesis in ABA-I strain was increased by 20.2 folds compared with that of the host strains.

Abstract:Aspergillus oryzae L-09 and Saccharomyces cerevisiae Z-06 were mixed cultured, and the component of the submerged culture medium was optimized. In the optimum medium, the activities of the α-galactosidase and invertase reached 85.22 U/mL and 563.44 U/mL, which were 5.9 and 8.3-fold higher than for the single strain, respectively.

Abstract:A halobacteria strain Z4 producing extracellular halophilic lipase screened from Hypersaline lakes of Inner Mongolia was identified as Haloterrigena thermotolerans. The crude lipase from Z4 was partially characterized using p-NPB. The activity of crude lipase was markedly increased 20%~30% by metal ions (Ba2+,Fe2+,Cu2+), but was obviously decreased 20% by EDTA. The lipase was completely inhibited by PMSF. The activity and heat resistance of enzyme was increased by NaCl, suggesting that the enzyme has strong dependence and specificity on NaCl. The thermostability of the crude enzyme was increased by alcohols, the glycerin is the best one. The optimum conditions for the crude lipase hydrolyzing p-NPB were followed: 3.5 mol/L NaCl, 70°C and pH 8.0, and the optimum conditions for the crude lipase hydrolyzing p-NPP were followed: 2.5 mol/L NaCl, 80°C and pH 8.0.

Abstract:Bdellovibrios are obligate predatory bacteria, widely distribute in nature and regulate the counts of bacterium in water. Fifteen strains of predatory bacteria were isolated from marine environment using Vibrio parahaemolyticus DX-1 as host and one of them formed large plaques designated as Bd-M1. The strain was confirmed by Bdellovibrio species-specific 16S rDNA fragment amplified using PCR method. Determination of host range on species of fish pathogenic bacteria (Vibrio parahaemolyticus, Vibrio alginolyticus, Vibrio anguillarum, Vibrio anguillarum, Vibrio vulnificus and Edwardsiella tarta) indicated that Bd-M1 was able to parasitize 20 strains out of a total of 22 tested. Co-culture experiment shown that Bd-M1 have purification function on Vibrio parahaemolyticus, the number of V. parahaemolyticus decreased from 3.0′108 CFU/mL to 8.7×103 CFU/mL during 102 h. Immersion Penaeus vannamei in water at different concentration of Bd-M1 was used in protection against experimental infection with V. parahaemolyticus DX-1 infection. Results shown that the mortality of groups bathed with Bd-M1 was lower than that group without Bd-M1. These results suggest that it may be possible to use bdellovibrio to control fish disease.

Abstract:The efficacy of the method of AlCl3 sedimentation and positive-charged membrane filtration for concentrating viruses was compared in this study. In addition, the efficacy of the two methods was also compared in different waters, conditions and elution. The recovery rate of the sedimentation method of AlCl3 and the positive-charged membrane was 96.0% and 92.0% respectively when tap water served as samples. The recovery rate of the sedimentation method of AlCl3 and the positive-charged membrane was 93.9% and 69.9% respectively when sewage served as samples. Compared with the two concentration methods, there was no obvious difference in tap water but significant difference in sewage. The results showed that the positive-charged membrane was adapted to the water samples with little impurity. According to the experiment results, the two methods could be used to effectively concentrate viruses in tap water. However, the sedimentation method of AlCl3 was recommended to the primary method in other water samples.

Abstract:Chromosomally encoded toxin–antitoxin (TA) systems are thought to result in growth arrest and eventual cell death upon exposure to environmental stress in E. coli. In the chromosome of cyanobacteria Synechocystis sp. PCC6803, the genetic organization of a 360 bp open reading frame (ORF), slr0664, and another small ORF of 256 bp, ssr1114, is similar to that of TA system. The predicted protein encoded by slr0664 is homologous to RelE, but neither homologue of ssr1114 nor ssr1114-encoding protein was found in TA system. To see whether slr0664 encodes a toxin protein, ssr1114 encodes an antitoxin, an expressing plasmid containing promoter Plac and PBAD, was constructed. In this construct, Both slr0664 and ssr1114 were controlled by Plac and PBAD, respectively. Expression of slr0664 in Escherichia coli results in the inhibition of bacterial growth, the expression of ssr1114 neutralize the toxicity of slr0664 expression. These results show that slr0664 is toxin gene and ssr1114 is antitoxin gene, both ssr1114 and slr0664 constitute a chromosomal TA system in Synechocystis sp. PCC6803.

Abstract:The volatile oils of endophyte isolates R1 (Acremonium sp.) and R2 (Acremonium sp.) from Aquilaria sinensis were extracted by solvent method. Twenty and sixteen ingredients were identified from the volatile oils of R1 and R2 by GC-MS, respectively. Fatty acids, such as oleic acid, linoleic acid, hexadecanoic acid etc., were the main components, whereas terpenoids like 1,8-cineole, zingiberene, ar-curcumene were also found in both oils. It’s the first report about the volatile oil constituents of endophyte isolates from A. sinensis.

Abstract:Recent demand for biodiesel worldwide has turned vegetable fats into an ever-growing and substantial consumption resource. In this regard, microbial lipids which triacylglycerol(TAG) is similar to the vegetable fats, may be a prospective alternative feedstock for biodiesel industry. Described herein are preliminary screening studies on Cryptococcus curvatus O3 strain for assimilation glucose to produce microbial lipids. Cryptococcus curvatus O3 When cultivated by shaking flask at 30°C with glucose as sole carbon source, cellular biomass and lipid content were 51.8 g/L and 65.1%. Therefor Cryptococcus curvatus O3 strain can be defined as an oleaginous yeast. Gas chromatography analysis of microbial lipids revealed that major constituent fatty acids were palmic acid, oleic acid and linoleic acid. The percentage of SFA (saturated fatty acid)in the lipid of Cryptococcus curvatus O3 is 64%. Such compositional feature was quite similar to cocoa butter, one of the high quality vegetable fats. Therefore, the oleaginous yeast could be considered as an ideal host for fermentation of biomass for lipids.

Abstract:Pestalotiopsis photiniae is one of the predominant pathogens of strawberry root rot disease. Based on preliminary research, it was proved that crude toxins were main pathogenic substances of the pathogen. For further investigation and utilization of toxins produced by this fungus, conditions of producing toxins were analyzed with the leaf disk method in this experiment. The result showed that pH values, cultural time, vibration, and tested temperatures obviously affected the production of toxins, except for light treatment. The most suitable culture conditions for the toxin production were pH 6.2, 25°C, darkness and stillness, for 5 d~7 d. Besides, it was discovered that crude toxins could significantly inhibit seed germination and elongation growth of roots or shoots for maize, rye and mung bean.

Abstract:Effects of mannan-oligosaccharide (MOS) on the growth of Lactobacillus were investigated by pure culture of three swine originated Lactobacillus strains or co-culture with swine pathogenic E. coli. The pure culture results revealed that OD values and lactic acid concentration of three Lactobacillus strains in the MOS supplemented cultures were higher than those of the control group without MOS supplementation, a lower pH was observed for MOS supplement compared with that of the control group. The co-culture results showed that MOS were utilized by both Lactobacillus strains and swine pathogenic E. coli strain. But Lactobacillus grew faster than the latter. A significant increase in lactic acid concentration (P<0.05) and a significant decrease in pH (P<0.05) were observed in the MOS supplemented co-cultures compared with those of the control group or pathogenic E. coli pure culture. Moreover, the changes in numbers of Lactobacillus strains and the pathogenic E. coli strain, the elevation of lactic acid concentration and the reduction of pH were observed to be obvious during the first 12 h fermentation.

Abstract:Six bacterial strains with malachite green decolorization ability were isolated from a sediment of aquaculture pond, and strain M6 was selected by further enrichment culture in nutrition broth with malachite green and decolorization rate comparison. The decolorization rate of strain M6 to malachite green was 97.14% in the conditon of 30°C and 150 r/min, and its morphology was observed by gram stain and electron microscopy, its physiological and biochemical characteristic was studied by ATB bacteria identification instrument for identification of bacteria, and its 16S rDNA sequence was determined following PCR amplification, the sequence was aligned and the phylogenic tree was instructed with those bacterial strains of high identity with strain M6. In addition, its growth characteristics was also studied. The experimental results showed that strain M6 was gram negative and bacilliform with a flagellum at one end. Its size was 0.45 mm ×0.84 mm. Its colony produced on common agar plate appeared as round, light blue, dense, hard to choose; 16S rDNA sequence of strain M6 had high identity of 98%~99% with Pseudomonas sp. located in GenBank and strain M6 had the most close relative relation to Pseudomonas putida OW-16 (Locus number: DQ112328.1). Combined the results of the traditional morphological, physiological, biochemical characteristics and 16S rDNA sequence analysis, strain M6 was identified as Pseudomonas putida (Locus number: EU348741.1). Additionally, its growth curve in the condition of 30°C and 150 r/min was as follows: lag phase was 0~4 h, log phase was 4 h~64 h, stationary phase was 64 h~80 h, decline phase was after 80 h. Its best growth conditions were pH 7 and 30°C,and in the rotational speed of 50 r/min to 250 r/min. Its concentration increased with the increase in rotational speed.

Abstract:This research is for the purpose of comparative analysis of the microbial flora structure in the chilled beef with no packing and cling film, which under the same terms of sale. It was used the V3 area fragment of 16S rDNA to carry on PCR-DGGE, Meanwhile used the 16S rDNA sequence to analysis the microbial flora structure of the two samples, according to the technology of clone .The research discovered that the flora structure displays a biggish difference; there was 6 OTU in the chilled beef with cling film, mainly was that Lactococcus(28%), Lactobacillus (26%), Carnobacterium(18%) and Brochothrix (10%); but there was 18 OTU in the chilled beef with no packing, mainly was that Lactococcus(28%), Brchothrix(18%), Acinetobacter (11%). The result indicates that cling film played a certain inhibitory action regarding the Staphylococcus as well as the cold pole bacteria and such bacterium. And it can provide a certain theory basis for the meat processing in the department of microorganism’s control.

Abstract:Five kinds of bacteria were isolated from disease Meretrix meretrix and culture water (two isolated from the M. meretrix, three from the culture water) in Lvsi harbor, Jiangsu province. The results of infection showed that strain WG1702 can cause disease with the mortality rate 100 percent and the same symptoms as original. It was cued that strain WG1702 was the pathogenic bacteria and caused the death in large scare, a preliminary research was done on the bacteria including morphological, physiological, biochemical characteristics, phylogenetic position and pathogenic. Strain WG1702 was a straight-rod gram negative bacterium, the physiological and biochemical indicators were lysine decarboxylase, ornithine decarboxylase, reduction of NO3- to NO2-, mannitose, oxidase and methylred reaction positive, arginine decarboxylase, arginine dihydrolase, salicin and voges-proskauer negative. In order to identify the bacteria phylogenetic position and a 16S rRNA molecular identification was done, PCR amplification got a size of about 1.5 kb gene fragment, The whole 16S rRNA sequences were determined, analyzed the homology of sequences and built the phylogenetic tree. Sequences analysis revealed that strain WG1702 exhibited the highest level of 97.4% similarity to Vibrio harveyi(DQ146937), combining morphological, physiological and biochemical identification results, the isolated strain WG1702 was identified as Vibrio harveyi.

Abstract:The fermentation broth of one actinomycete strain ACMA006 strongly inhibited growth of many tumor cells and some microorganisms, but its cytotoxicity to human normal cells were weak. Strain ACMA006 grow well on most tested media, producing exuberant vegetative hyphae and aerial hyphae. Its optimization temperature is 28°C. Phylogenetic analysis based on 16S rDNA sequence showed that strain ACMA006 was closely related to one of the genus Streptomycetes (S.cavourensis subsp. washingtonensis) with 16S rDNA sequence similarity values of 100%, but had many differences in other features including its morphology, physiological and biochemical characteristics. The preliminary study supported the view that the strain ACMA006 represented a new strain of the S.cavourensis subsp. washingtonensis.

Abstract:To clone Rv0859 gene of Mycobacterium tuberculosis and purify its fusion protein. Genome DNAs of H37Rv was extracted. Primers for Rv0859 gene was designed, and DNA fragments encoding Rv0859was obtained by PCR and inserted into proeukaryotic expression plasmid pET30a followed by digestion with Hind III and BamH I. pET30a-Rv0859 is connected by T4 ligase which was transformed into Escherichia coli JF1125. Sequence analysis was performed to verify the recombinant plasmid. The recombinant plasmid was transfected into Escherichia coli BL21. After induction with IPTG, the expression of Rv0859 protein was identified by SDS-PAGE and mass spectrum. The expressed protein was the maximum when induced with 0.05 mol/L IPTG for 4 h at 37°C. The polyclonal antibodies were prepared to detect the subcellular localization by Western-blotting. The result is the prokaryotic expression vector pET30a-Rv0859 was constructed successfully and the recombinant Rv0859 was expressed heavily. The result of Western-blotting indicated that the protein located on the cell envelope partly and little on the cell well. The study laid the foundation for application in the tuberculosis.

Abstract:Rare-earth elements are characterized with their biological effects on some organisms. Besides the increase production effect in agriculture, rare-earth elements also have antimicrobial effect in clinic. Recently, the antimicrobial effect and mechanism of rare-earth elements are under investigation by some scholars. This paper summarized the antimicrobial activity and application of rare earth compounds and complexes, including Hormesis effect of rare-earth elements to some microorganism, synergistic effect of rare-earth elements with antibiotic, synthesis of some rare earth complexes, and the application of rare earth compounds in antibacterial materials. Then the antimicrobial mechanism of rare earth compounds and complexes have been discussed. At last, the application for foreground and essentiality of rare earth compounds and complexes in antimicrobial field will be expected.

Abstract:Antimicrobial peptides, a cluster of small peptides secreted by the majority of creatures, have been demonstrated with activity against a wide range of microorganisms including bacteria, protozoa, yeast, fungi, viruses and even tumor cells. These peptides have some features such as broad spectrum , high efficacy and stability, little drug resistance. A lack of new antibiotics combined with emerging multi-drug resistance issues demands that new antimicrobial strategies be explored for treating these infections. It has been proposed that the antimicrobial peptides might form the foundation for a new class of clinically useful antimicrobials. We review the advantages of these molecules in construction features and bioactivity, with the focus on the mechanism and clinical applications.

Abstract:Usage of reverse genetic techniques in the research area of the fundamental etiology of foot-and-mouth disease virus (FMDV), has resolved the issue about the function of viral gene of FMDV on genomic integer level. At present, a further recognition and apprehension for the molecular etiology of FMDV based on the development in reverse genetics was made. Combined with the research work in our labs, we reviewed international advances about the molecular pathogenic mechanism, the relationship between virulence and variation in the genomes, influencing factors for the viral replication, and the development of new-type gene vaccine of FMD in this article, and propose the potential research aspects in reverse genetics of FMDV in the future.

Abstract:Pathogenic microorganism always is influencing factor of the aquatic product security. In this paper, the main pathogenic microorganisms and their pollution actuality in the current aquatic products were expatiated, rapid detection of pathogenic microorganisms on the progress of new technology was introduced, and the prevention measures and proposals how to control the pollution of pathogenic microorganisms in aquatic products were put forward.

Abstract:Succinic acid is regarded as C4 platform chemical, which has a huge potential market with wide applications in biopolymer, food, medicine, and so on. Production of succinic acid by microorganism fermentation has attracted much attention in recent times. By fermentation, succinic acid could be produced from renewable resources in place of petroleum with low cost and low pollution; especially CO2 could be fixed by microorganism to form the product, which is a promising way to deal with the green gas. Some E. coli have been chosen as good succinic acid producing strains because of their clear genetic backgrounds, convenience to be modified and controlled, and good growth properties with low nutrients requirements. The progress of genetic engineering strategy and metabolic engineering technology for construction of succinic aicd producing recombinant E. coli has been introduced in this paper with the discussion of the future research in this area.

Abstract:This paper reviewed the research progression in lactic acid bacteria which can reduce the cholesterol in vivo and in vitro. It also approached the function and the mechanism of lactic acid bacteria in decreasing serum cholesterol, proposed some problems existing in the research. All these will be useful to the exploitation and utilization of lactic acid bacteria.

Abstract:Hepatitis E, a newly emerging zoonotic infectious disease, is of major public health concern worldwide. Its pathogen is hepatitis E virus (HEV), which is in most cases enterically transmitted. Pigs are regarded as the major virus reservoir. The epidemic state of the disease is complicated in China. There exist genotype 4 and/or 3 HEV in pig farms. Gene recombination and quasispecies of HEV is providing genetic foundation to the evolution of the viruses. Consuming contaminated pig meat and organs is the major cause of infection with the zoonotic pathogen. Research is needed to throw light on the relationship of swine HEV with other epidemic pathogens in pig farms. Real time inspection of genetic and pathogenic variation of swine HEV will provide valuable information for taking proper prophylaxis measures. Analysis of epidemic state of swine HEV should be one of the key issues in Veterinary Public Health (VPH) system.

Abstract:This paper discussed the application of designing experiments from scientific research in Microbiology courses and its effects on the teachers and students. The problems of the application of designing experiments in Microbiology courses were analyzed. The practice of the teaching reform showed that it give great advantages for the undergraduates with the enhancement of their ability on theory application and scientific innovation. This teaching reform could be widely popularized.

Abstract:“Microbiological Examination” is an important core course for medical examination technology major with a strong attribute of practicality and operability. A method of “Cooperation between school and hospital” is employed in the teaching of the course. It is based on the standards for medical professional education required by the hospitals, coupled with our teaching program. In the course of teaching, emphasis is laid on the philosophy of work-learn combination, using methods such as the analysis of individual cases to broaden students’ thinking and develop a sound scientific attitude. By way of “training-on-job learning-interning”, we can cultivate students’ ability of working with their own hands, as well as that for analyzing and solving problems. In this way, our school will be able to provide “talents with medical examination skill that can be put to practical use” for clinical application.

Abstract:The major goal of microbial ecology is to study the structure and function of complex microbial communities. New molecular biological techniques have been successfully applied to analyze microbial community structure. However they do not provide information on the physiologic properties of the detected microorganisms. A new tool for structure-function analyses in microbial ecology, microautoradiography combined with fluorescence in situ hybridization (MAR-FISH) can be used to simultaneously examine the phylogenetic identity and the specific activity of microorganisms within a complex microbial community at a single-cell level. This article reviews the principle, experimental steps of MAR-FISH technique. The application of this technique in study of the environmental microbial community and function is also summarized.

Abstract:To clone, express and primarily use human autoantigen Sm D1 in methylotrophic yeast Pichia Pastoris. The gene Sm D1 was cloned by PCR.The PCR product was inserted into the vector pPIC9k. The recombinant plasmid pPIC9k- Sm D1 was transformed into yeast SMD1168 by electroporation. The positive clones were screened in MD plates. The high copy number transformants were rapidly selected by using G418 and were induced by methanol. Supernatants after induction were analyzed by SDS-PAGE and immunodot. The PCR product was showed about 360 bp in size which was in accordance with predicted. The pPIC9k-Sm D1 showed the same seqencing result with GenBank’s report and restriction enzyme analysis confirmed our prediction. The pPIC9k-Sm D1 positive clone produced an about 16 kD protein which had natural immunogenicity of human autoantigen Sm D1 by SDS-PAGE and immunodot. The sensitivity and specificity of immunodot were 96% and 100%, respectively. The agreement between immunodot and immunoblot was 98%. Successfully cloning and high-level expression of human autoantigen Sm D1 in methylotrophic yeast Pichia pastoris laid a foundation for further research work.