Abstract:Abstract:[ Objective] To isolate and identify the new Bdellovibrio strains from the sea mud of Shenzhen bay and to preliminarily study their biological characteristics. [Methods] We isolated Bdellovibrio strains by DNB(dilute nutrient broth) double-layer plate method. Their 16S rDNAs were sequenced and their morphologies were examined under electron microscope. We identified these strains according to the ninth edition of Bergey’s manual of determinative bacteriology. We also studied their biological characteristics through physiological tests. [Results] We isolated 2 strains of Bdellovibrio sp. (5#-12 and 5#-sh06) from sea mud of Shenzhen bay. Both strains grew between 20℃ and 35℃, with 25℃ and 30℃ as optimal temperature for 5#-12 and 5#-sh06, respectively. They grew between pH 6.1 and 8.6, and the opti℃mal pH for both was 7.2. Lysis experiments on 58 strains of pathogens were conducted and the results showed that 5#-12 and 5#-sh06 lysed 46 and 48 strains, corresponding to 79.3% and 82.8% of lysis abilities. Taken both two Bdellovibrio strains together, they lysed 96.6% (56 strains) of tested pathogens and 100% of tested vibrios (39 strains). [Conclusion] The results demonstrated that Bdellovibrio have potential and significant application prospect for elimination of pathogens.

Abstract:Abstract: There are lots of actinorhizal plants distributed in coastal area and mountains in Fujian province, China. [Objective] The aim of this study is to describe the genetic diversity of Frankia strains symbiotically associated with several species of Casuarina, Myrica, Alnus and Elaeagnus in Fujian. [Methods] Genomic DNA was extracted from Frankia strains and used as template in PCR with the primers targeting two DNA regions, one in ribosomal operon, and the other in nif D-K gene. PCR products were then digested by using a set of restriction endonucleases to generate the restriction fragment length polymorphism patterns. [Results] Except 2 strains nodulating M. rubra and a strain infecting E. oldhami, 17 Frankia strains had an amplified fragment of rrn region in 16S-23S rDNA intergenetic spacer (IGS), 12 Frankia strains nodulating C. equisetifolia, C. cunninghamiana and C. glauca living in 6 geographical origins had high homogeneity and were assigned to one group by clustering analysis, 5 strains from M. rubra and A. cremastogyne were closely related and fell to the other group. All 25 Frankia strains showed a single copy of IGS nif D-K and generated 8 PCR-RFLP patterns while clustering into 3 different groups. Frankia strains nodulating three species of Casuarina in seven different sites had a high degree of genetic similarity to cluster one group. Isolates infecting M. rubra, A. cremastogyne and A. formosana were closely related and belonged to the other cluster, Frankia from E.oldhami owed a quite different cluster. [Conclusion]These results demonstrated that there is great genetic diversity among Frankia microsymbionts in Fujian.

Abstract:Abstract: [Objective] Vairimorpha ceraces is a new microsporidium that isolated from the insect of Lepidoptera, Cerace Stipatana (Walker). We used 16S rDNA sequence to explore genetic status of Vairimorpha ceraces. [Methods] SSU rDNA (small subunit ribosomal RNA) of Vairimorpha ceraces was cloned and sequenced for constructing phylogenetic tree through Neighbor-joining. [Results] The core sequence of SSU rRNA of Vairimorpha ceraces with a length of 1228 nucleotides (GenBank EU267796) was successfully cloned and sequenced. Phylogenetic analysis showed that Vairimor-pha ceraces was closer to the species of Vairimorpha sp. Germany (GenBank AF124331) and Vairimorpha imperfecta (GenBank AJ131645), both isolated from Plutella xylostella. The three species of genera Vairimorpha included Vairi-morpha ceraces formed a clade with the Nosema spp. which from Lepidoptera host in phylogenetic tree. Conversely, other three Vairimorpha spp. from Lepidoptera (Vairimorpha necatrix, Vairimorpha sp. NISM12 and Vairimorpha lymantriae) were mixed with Nosema spp. from non-lepidopteran host in the other clade. [Conclusion] Combined with the biological characters, Vairimorpha ceraces was a member of genera Vairimorpha, Family Nosematidae.

Abstract:Abstract: [Objective] To confirm Burkholderia cepacia complex (Bcc) genomovars from agricultural niches and clinical samples, and to evaluate their possible virulence to human body on alfalfa infection model in China. [Methods] A total of 57 Bcc strains were isolated and collected from the rhizosphere, soil and clinical samples in China. The genomovars composition of the Bcc strains was analyzed by species-specific PCR tests, and the virulence of the Bcc strains was tested on alfalfa seedlings. [Results] Four genomovars of the ten genomovars were detected among the Bcc strains, including B. cepacia (genomovarⅠ), B. cenocepacia (genomovarⅢ), B. vietnamiensis (genomovarⅤ) and B. pyrrocinia (genomovar Ⅸ). Bcc genomovarsⅠandⅢA from clinic, and genomovarⅢB from rhizosphere were the most virulent in the alfalfa infection model, and caused symptoms in 69%, 68% and 55% of seedlings, respectively. There were significant variances in the mean percentage of seedlings with symptoms for genomovarsⅠ,ⅢA andⅢB compared to those for genomovarⅤandⅨ. [Conclusion] There was difference in the ability to cause disease in alfalfa for different genomovar strains from agricultural inches. The strains of Bcc genomovarⅢB from rhizosphere were more virulent similar to those of Bcc geno-movarⅢA from clinic.

Abstract:Abstract: [Objective] Based on a proteomic reference map of the important probiotic organism Bifidobacteria longum NCC2705 constructed by our previous research, we compared the proteomic profiles of Bifidobacteria longum strain NCC2705 grown on lactose or glucose to identify the catabolic route allowing lactose fermentation. [Methods] We con-sidered the proteins differentially expressed if their relative volume deviated more than 3-fold with ImageMaster 2D Elite version 5.0 software. Interesting spots were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis, and phosphorylation analysis of proteins with mobility changes by Pro-Q Diamond Stain. [Results] The identified spots represent 31 protein entries, 14 up-regulated proteins, 17 down-regulated proteins. These identified proteins, which were hydrophilic proteins and their genes with CAI value above 0.5 represented the most abundant proteins, included key stress proteins, metabolism-related proteins, and proteins related to translation. Two proteins including Tal (BL0715, transaldolase, L3) and Pyk (BL0988, pyruvate kinase, G9) exhibited clear post-translational modification. [Conclusion] Proteomic comparison of glucose- and lactose-grown cells revealed that lactose and glucose were catabolized via the same degradation pathway, and the rate of glucose assimilation was higher than that of lactose. Spot and protein analysis revealed that post-translational modifications might be common in these proteins. Pro-Q Diamond staining analysis revealed that lactose trigger Tal phosphorylation at 43 T /47 S, and inhibited Pyk phosphorylation at 65 S. These proteins were identified for the first time as bifidobacterial phosphoproteins.

Abstract:Abstract: [Objective] Lactococcus lactis with high acid adaptive capacity was screened, and the influence of acid adap-tation on membrane fatty acid profile and expression of membrane proteins were studied. [Methods] Lactococcus lactis KLDS4.0312 with high acid adaptive capacity was screened from 12 lactic acid bacteria and 8 Bifidobacterium. The change of the fatty acid profile in cell membrane of this strain was analyzed by gas chromatography-mass spectrometry, and two dimensional polyacrylamide gel electrophoresis method was used to analyze the differential expression of mem-brane proteins during the acid adaptation. [Results] After acid adaptation, Lactococcus lactis KLDS4.0312 increased the proportion of unsaturated fatty acids from 30.77% to 42.93% in its membrane lipids with a concomitant decrease in satu-rated fatty acids from 69.23% to 57.07%, and a new long-chained, mono-unsaturated fatty acid C19:1-n6 was induced. Compared with the non-adapted sample, there were at least 65 distinct protein points in the adapted sample, where 43 proteins were up-regulated and 22 proteins were down-regulated. But the acid adaptive capacity of Lactococcus lactis KLDS4.0312 was eliminated by adding chloramphenicol which can restrain the synthesis of new proteins. [Conclusion] These results showed that change in the membrane fatty acid profile by acid adaptation in Lactococcus lactis KLDS4.0312.

Abstract:Abstract: [Objective]3-deoxy-D-arabinoheptulosonate-7-phosphate synthase (EC 2.5.1.54;DS) is the key enzyme in tryptophan synthesis pathway. Cloning DSⅠgene from Corynebacterium pekinense and expression of DSⅠgene might facilitate testing the existence and function of DSⅠin Corynebacterium pekinense. [Methods] According to the homology between Corynebacterium glutamicum ATCC13032 and Corynebacterium pekinense, we designed a pair of PCR primers to clone the DSⅠgene from wild-type C. pekinense AS1.299 and its mutant PD-67, then the mutant DSⅠgene was ex-pressed in C. pekinense PD-67 by subcloning the the PCR fragment into plasmid pAK6. [Results]Analysis of PCR frag-ments revealed that they contained the whole DSⅠgene. There was no base change all over the structure genes and regu-latory sequences between C. pekinense AS1.299 and PD-67. An internal promoter was found in the upstream of the DSⅠgene from C. pekinense and it functioned in E. coli 3257. The DSⅠgene from C. pekinense PD-67 was expressed ho-mogenously, and the specific enzyme activity of DSⅠin C. pekinense PD-67(pAD1) was much higher than that of the control strain C. pekinense PD-67(pAK6). [Conclusion] This is the first report that DSⅠgene existed in Corynebaterium Pekinense, The amplification of the specific activity of DSⅠis expected to increase L-tryptophan accumulation of C. pekinense PD-67.

Abstract:Abstract: [Objective] Cloning of a Homologous Gene of PMK1 Type Mitogen-Activated Protein Kinase (MAPK) from the rice false smut fungus Ustilaginoidea virens. [Methods] According to the conserved amino acid sequence of several filamentous fungus MAPKs, which were homologous to Magnaporthe grisea PMK1, degenerate PCR primers were de-signed to amplify the MAPK internal DNA fragment from Ustilaginoidea grisea. The complete UVMK1 DNA and cDNA sequences were obtained using Thermal Asymmetric Interlaced–PCR (TAIL-PCR) and RT-PCR methods. Functional Iden-tification was done by using the M. grisea ΔPMK1 mutant stain nn78, including appressoria differentiation assay and bar-ley infection test. [Results] The total length of UVMK1 was 1435 bp. It contained 3 introns and encoded 355 amino acids. The induced amino acid sequence showed identical to Magnaporthe grisea PMK1, Fusarium oxysporum FMK1, Fusarium solani FsMAPK, Colletotrichum lagenarium CMK1, Botrytis cinerea BMK1, Claviceps purpurea CMPK1. After transfor-mation of the ΔPMK1 mutant of M. grisea using a complement vector with the complete cDNA of UVMK1 (under the M. grisea MPG1 promoter), five transformants were obtained. Furthermore, the selected two transformants fully restored their ability to form appressoria and infect a barley leaf. [Conclusion] In this study, we characterized the frst MAPK protein from U. virens, and that UVMK1 is a homologue of M. grisea PMK1.

Abstract:Abstract: [Objective] To assess the environmental release risk of genetically engineered microorganism Sphingomonas sp. m-CDS-1. [Methods] Pesticides detection, plates counting, most probable number-PCR (MPN-PCR) and denaturing gra-dient gel electrophoresis (DGGE) were used to study the pesticides degrading effects, the decline dynamics of m-CDS-1, and the effects of release of m-CDS-1 on community structure of soil microorganisms. [Results] m-CDS-1 (1.01× 107CFU/g dry soil) could degrade both 10.71 mg/kg methyl parathion and 1.29 mg/kg carbofuran in 30 days. m-CDS-1 declined quickly with time, and could not be detected anymore in 30 days. Release of m-CDS-1 would not change the number of the cultivable microorganisms notably. The similarities of PCR-DGGE profiles between the pesti-cides applied treatments and the controls in 4, 11 and 30 days were 17.16 %, 49.81 % and 75.01 %, and the similarities between the m-CDS-1 released treatments and controls were 49.57 %, 38.3 % and 83.3 %, respectively. In 60 days, DGGE profiles of all treatments and controls had high similarities. [Conclusion] m-CDS-1 could degrade both pesticides re-markably in the field, and would not be the predominant population, and would not affect the community structure of soil microorganisms in the long term.

Abstract:Abstract: [Objective] The aim of this study was to (i) isolate and characterize bacteria capable of degrading p- nitrophe-nol (PNP); (ii) determine the kinetics of biodegradation, (iii) clone and express the PNP-degrading related genes. [Meth-ods] Enrichment method and serial dilution spread-plate method were employed to isolate PNP-degrading strain. Mor-phological, physiological & biochemical tests and 16S rDNA sequence analysis were used to identify the isolate. Degra-dation kinetics was studied by flask test. PNP-degrading related genes were cloned by SEFA-PCR method. Hydroxyquinol 1,2-dioxygenase encoding gene pnpC was cloned into pET29a to construct the recombinant plasmid pETpnpC and ex-pressed in E. coli BL21 (DE3). The activity of the expressed product was determined by spectrophotometric method. [Results] Strain PDS-7 capable of utilizing PNP as the sole carbon, nitrogen and energy source was isolated and identified as Pseudomonas sp. It could tolerate the PNP concentration up to 80 mg/L, the optimal temperature for degradation was about 30°C and alkaline pH benefited PNP degradation. Hydroxyquinol 1,2-dioxygenase and maleylacetate reductase en-coding gene pnpC and pnpD were cloned and sequenced respectively, the sequence was deposited in GenBank with the accession number EU233791. pnpC was expressed in E. coli BL21 (DE3), the expressed product in cell-free crude extracts showed ortho ring cleavage activity to hydroxyquinol and catechol, with the special activity 0.45 U/mg protein and 0.37 U/mg protein, respectively, indicating pnpC gene encoding hydroxyquinol 1,2-dioxygenase was actively expressed. [Conclusion] One PNP-degrading strain Pseudomonas sp. PDS-7 was isolated and identified. Its degradation kinetics was studied. Its degradation relevant genes were cloned and expressed.

Abstract:Abstract: Acetohydroxyacid synthase (EC 4.1.3.18) is the enzyme that catalyses the first step in the synthesis of the branched-chain amino acids valine, leucine and isoleucine in plant, fungi and bacteria, and also is target of the sulfony-lurea, imidazolinone, triazolopyrimidine and other acetohydroxyacid synthase inhibitor herbicides. [Objective] The pur-pose of this study is to get the resistant gene, prepare a functional bacteria with acetohydroxyacid synthase, and investi-gate the relationship between the mutation sites of the acetohydroxyacid synthase and the herbicides-resistant. [Methods] A metsulfuron-methyl-resistant bacterium Lm10 was isolated from metsulfuron-methyl contaminated soil. Acetohy-droxyacid synthase genes ilvIH was amplified from the genome DNA of strains Lm10 by PCR. The ilvI and ilvH were cloned into the bacterial expression vector pET29a(+) respectively. [Results] Strain Lm10 was identified preliminarily as Pseudomonas sp.. It can endure 14000 mmol/L metsulfuron-methyl and showed cross resistance to diffenent acetohy-droxyacid synthase inhibitor herbicids, such as chlorsulfuron, imazethapyr, flumetsulam and penoxsulam. The alignment result of the ilvIH amino acid sequence showed that ilvI of strains Lm10 differed from that of strain KT2440 by 6 sites, While the ilvH of the two strains were the same. The gene ilvI and ilvH were functional expressed in the Escherichia coli strain BL21(DE3) respectively. The expressed production pET-I displayed acetohydroxyacid synthase activity and showed re-sistance to high concentration of metsulfuron-methyl. [Conclusion] The ilvI displayed acetohydroxyacid synthase activity. The 6 different sites in ilvI of strains Lm10 probably led to herbicids resistance.

Abstract:Abstract: [Objective] The toxin produced by Erwinia chrysanthemi pv. zeae has not been reported so far. Toxin is one of the important pathogenic factors for plant pathogenic bacteria. The separation and purification of toxin are the key and basal work for toxin functional study. [Methods] We used several chromatography columns, chemical and biochemical methods for Erwinia chrysanthemi pv. zeae toxin separation and its characterization. [Results] We obtained a pure ingre-dient T3 of Erwinia chrysanthemi pv. zeae toxin . It was a yellow solid and dissolved in methanol, N-butyl alcohol(NBA), water and formic acid. It dissolved weakly in acetone but did not dissolve in trichloromethane and ethyl acetate. The re-sults showed that T3 toxin ingredient was neither carbohydrate nor protein, and was sensitive to ultraviolet ray. Biological assays of the toxin showed that it could inhibit rice growth, cause rice seedlings to wilt and make tobacco cells necrosis. Toxin with high content could inhibit buds and roots of rice, corn, tomato and tobacco to grow, whereas toxin with low content could promote their growth. In addition, the toxin inhibited 10 plant pathogenic bacteria with 5 genera. Further-more, toxin T3 induced the activities of phenylalanine ammonia-lysae(PAL) and peroxidase(POD) in rice. [Conclusions] It is the first report about the separation and purification of E.chrysanthemi pv.zeae toxin. The T3 toxin of E. chrysanthemi pv.zeae had the biological characters with inhibiting plant seeds germination, causing rice seedlings wilt, inhibiting some plant pathogenic bacteria and inducing defense enzyme activities in rice.

Abstract:Abstract: [Objective] To develop siRNA as a potential tool for control of porcine circovirus 2 (PCV2) infection. [Meth-ods] We designed two short interfering RNAs (siRNAs) related to the replicase (rep) gene of porcine circovirus and one related to capsid (cap) gene of PCV2 basd on the genomic sequences of the viruses deposited in GenBank. The corre-sponding DNA fragments were synthesized, annealed and ligated into the downstream of the mouse originated U6 pro-moter of the RNAi-Ready pSIREN-RetroQ ZsGreen vector. As controls, the siRNAs specific to Luciferase contained in the vector kit and negative fragments with no similarities to any known species were also included. We transformed the recombinant plasmids into the host bacterium DH5α and positive clones were selected. The positive clones were se-quenced and five clones carried the correct inserts. They were designated as Retro-SH1，Retro-SH4，Retro-SH6，Retro-Luc and Retro-NC. To test whether the siRNAs specific to PCV expressed by the vector could inhibit the virus replication, we evaluated the inhibition effect on PCV2 replication both in Dulac cells and experimental mice using real-time PCR and immunohistochemistry. [Results] The results showed that the purified plasmids could strongly inhibit the replication of the PCV2 virus and the inhibition rate reached to 99% in cell culture. In the animal experiments, siRNAs expressed by the plasmids could inhibit the replication of the PCV2 virus and the inhibition rate varied from 26% to 99%. [Conclusion] The siRNAs specific to PCV2 expressed by vectors should be potential in the control of the diseases related to PCV2 in-fection.

Abstract:Abstract: [Objective] We tested the antigenicity of porcine rotavirus Vp7 gene expressed in Lactobacillus. [Methods] We studied the condition of electroporation and transformed the plasmid pW425et-Vp7 into thyA gene-mutant L. acidlophilus. Then the positive clone was selected and its expression was detected by SDS-PAGE and Western blot. In our test, the BALB/c mice were drenched by the above-mentioned recombinant strain and SIgA was detected by ELISA. In addition, we also tested the protection of the recombinant strain through attacking porcine rotavirus to the mice immunized (content of virus was 15 mg/mL). [Result] Vp7 gene expressed in Lactobacillus with approximate 40.77 kDa fusion protein was observed by SDS-PAGE. The protein had the reactionogenicity with the antibody of porcine rotavirus through Western blot. We also detected the specific SIgA from the mice immunized by ELISA. Moreover, we observed that only 23% mice had diarrhea after attacking porcine rotavirus, which was immunized by recombinant strain. [Conclusion] Vp7 gene was expressed in Lactobacillus successfully. It had good immunogenicity and protection against porcine rotavirus. Moreover, the test further proved that the recombinant strain could be applied in the study on porcine rotavirus vaccine in the future.

Abstract:Abstract: [Objective] To screen the Madin-Darby bovine kidney cell strains for stable expression of capsid protein of foot-and-mouth disease virus (FMDV ). [Methods] We obtained two genes coding for capsid precursor protein (P1-2A) and protease (3C) of FMDV by PCR from recombinant plasmids pMD-P1-2A and pMD-3C.The recombinant retroviral vector pBABE-puro/P1-2A-3C was constructed by inserting P1-2A gene and 3C gene into pBABE-puro. Both the recombinant plasmid pBABE-puro/P1-2A-3C and the plasmid pVSV-G were co-transfected into packaging cells GP2-293 by liposome-mediated transfection method. As a result, the recombinant pseudovirus was produced. The pseu-dovirus infected the interesting target cell MDBK. The infected MDBK cells were selected by puromycin(2.5 mg/mL) for 2 weeks. The monoclonal cells were selected using cloning rings. The expression of capsid protein was detected by indirect immunofluorescence and sandwich-ELISA. The empty capsids of FMDV were observed under electron microscope. [Re-sults] The capsid protein of FMDV was expressed in MDBK cells. The expression levels in screened cell strains of various passages showed no significant difference. [Conclusion] The MDBK cell strains for stable expression capsid protein of FMDV were successfully screened, which laid a foundation of development of FMDV subunit vaccine.

Abstract:Abstract: [Objective] We report a new molecular technique for the analysis of four categories of diarrheagenic Es-cherichia coli based on the separation of PCR-amplified target fragments by denaturing high-performance liquid chroma-tography (DHPLC). [Methods] Enteropathogenic E.coli, enterotoxigenic E.coli, enterohemorrhagic E.coli and enteroin-vasive E.coli were identified by analyzing four specific virulence genes. [Results] A total of 32 bacterial strains were tested, giving no false-positive or false negative results. The detection limits were as low as: ETEC 27 CFU/mL, EPEC 33 CFU/mL, EHEC 25 CFU/mL and EIEC 42 CFU/mL. [Conclusion] The data suggest that PCR-DHPLC will be useful for diarrheagenic Escherichia coli detection and identification.

Abstract:Abstract: C-di-GMP [Bis-(3′,5′)-cyclic dimeric guanosine monophosphate] is a novel global second messenger in bacteria. The diguanylate cyclase and phosphodiesterase involve in c-di-GMP synthesis and degradation, respectively. alr3504 in Anabaena PCC7120 possibly encodes diguanylate cyclase with a coserved GGDEF domain. [Objective] For functional characterization, [Methods] the deletion mutant of alr3504 was constructed by using marker exchange method. [Results]No significant differences were found in the cell morphology, growth rate or heterocyst development between the deletion mutant and the wild type strain. But the mutant was more sensitive to Na+-salt under salt-stress. [Conclusion] The results show that alr3504 did not affect heterocyst development directly, but involved in other signaling pathway, which lay a foundation for exploring the abundant and complex signal transduction of cyanobacteria.

Abstract:Abstract: [Objective] To obtain the crystal of 5′,5′′′-P1,P4-tetraphosphate phosphorylaseⅠ(Apa1) of Saccharomyces cerevisiae for X-ray crystal structure and function analysis. [Methods] We amplified the coding region of an N-terminally truncated version of Saccharomyces cerevisiae diadenosion 5′,5′′′-P1,P4-tetraphosphate phosphorylase I (Apa1dn16) , and cloned it into the pET28 derived expression vector. After having screened the recombinant plasmids by PCR and confirmed them by DNA sequencing, we transformed a positive recombinant plasmid into the Escherichia coli BL21(DE3) cells for efficient expression. Then the expression and solubility of the recombinant Apa1dn16 protein were analyzed by SDS-PAGE after proper concentration of IPTG induction. Following that, we collected the soluble Apa1dn16 protein and purified it to homogeneity by sequential Ni-NTA affinity chromatography and Superdex 75 gel filtration, and then detected the purity and molecular weight of the desired protein by SDS-PAGE and mass spectrometry . In addition, we screened the crystallization conditions of Apa1dn16 with Hampton Research kits using the hanging drop vapor diffusion method. [Results] We efficiently expressed an N-terminally truncated Saccharomyces cerevisiae diadenosion 5′,5′′′-P1, P4-tetraphosphate phosphorylaseⅠin Escherichia coli BL21(DE3). The recombinant protein was partially soluble and was purified to homogeneity with a single band of ~36 kDa after SDS-PAGE. Mass spectrometry analysis further confirmed the purity and intactness of the recombinant protein.Moreover, we obtained the needle crystals of Apa1dn16 by hanging drop vapor diffusion method. [Conclusion] Escherichia coli BL21(DE3) is an efficient expression system for producing enough quantity of Apa1dn16 protein. The purified recombinant Apa1dn16 protein is suitable for crystallization and further structural investigation.

Abstract:Abstract: [Objective] In order to display extracellular lipase Lip2 from Yarrowia lipolytica on the surface of yeast Saccharomyces cerevisiae for whole cell catalysts. [Methods] The mature Lip2 encoding fragment was amplified from Yarrowia lipolytica total DNA, and was inserted into the 3′terminal of AGA2 to give the plasmid pCTLIP2 for surface display of Lip2. Olive oil, tributyrin and p-nitrophenyl palmitate (pNPP) were used as substrates to measure lipase activity. Moreover, the characterization of displayed lipase and its free form was analyzed. [Results] The surface displayed lipase was confirmed to be active towards olive oil, tributyrin and p-nitrophenyl palmitate (pNPP), and reached its highest expression level at 182 U/g dry cell after induced by galactose for 72h. The optimum temperature of cell surface displayed Lip2 was 40℃ After incubated at 50℃ for 4h, the surface displayed lipase retained 23.2% of its full activity, improved a little compared to free Lip2. The surface displayed lipase showed a preference to medium-chain and long-chain fatty acids p-nitrophenyl esters (C8-C16). [Conclusion] The cell surface display system based on a-agglutinin is an effective system for displaying Lip2, and the whole cell EBY100-pCTLIP2 will be probably suited to a different range of applications.

Abstract:Abstract: CRISPRs (Clustered Regularly Interspaced Short Palindromic Repeats), the basis of spoligotyping technology, can provide prokaryotes with heritable adaptive immunity against phages’ invasion. Studies on CRISPR loci and their associated elements, including various CAS (CRISPR-associated) proteins and leader sequences, are still in its infant period. We introduce the brief history1, structure, function, bioinformatics research and application of this amazing immunity system in prokaryotic organism for inspiring more scientists to find their interest in this developing topic.

Abstract:Abstract: The bacterial antioxidant defense system, including oxyR; soxRS; perR and ohrR, is employed to cope with oxidative stress induced by respiration or environmental assaults. oxyR, encompasses the gene encoding OxyR and some other genes and operons regulated by it, has captured the highest attention among these regulons. To date, members of oxyR regulon have been confirmed to participate in many physiological processes including antioxidant defense, repression of spontaneous mutagenesis, virulence, iron metabolism and out membrane protein phase-variation. Though controversy still exists among researchers, molecular mechanism of transcription regulation by OxyR has been intensively investigated in Escherichia coli. The diverse physiological processes participated by oxyR regulon have facilitated its applied research, such as screening for mutagens and dealing with antimicrobial resistance problems frequently occurring in industrial plants. This paper reviewed the recent progress of oxyR regulon, focusing on members regulated; physiological processes participated; mechanics and factors affected its transcription regulation activity, in order to bring some insights to further investigation of antimicrobial resistance and mutagens screening.

Abstract:Abstract: Anoxygenic phototrophic bacteria (APB) are good model organisms used to study the origin and evolution of life, photosynthesis and nitrogen fixation mechanism. With increasingly available genetic information and establishment of sequencing techniques for nucleic acid, more attention has been paid to exploration of APB resources from various habitats especially extremely environment. The pace of new species description has been increasing in recent years, and some new taxonomic taxa are also proposed, therefore, it?is?necessary?to?redefine?APB?and?provide the?newest?taxonomic?system of APB. We reviewed the problems and prospect about taxonomy of anoxygenic phototrophic bacteria. The definition, situation of the taxonomy, characteristics for APB identification are noted and commented from the discovery of APB up to now.