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| There are 55 papers published in subject: > since this site started. | |||
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| 1. Pseudobodo sp, a new pathogen for a potential energy-producing algae: Chlorella vulgaris cultures | |||
| Chen Zhangran,Lei Xueqian,Zhang Jingyan,Zheng Wei,Zheng Tianling | |||
| Biology 28 November 2013 | |||
| Show/Hide Abstract | Cite this paper︱Full-text: PDF (0 B) | |||
| Abstract:Chlorella vulgaris, which could serve as a potential source of food and energy because of its photosynthetic efficiency, is a genus of single-celled green algae, belonging to the phylum Chlorophyta. In our study, a pathogenic organism targeting C. vulgaris was discovered. 18S rRNA gene sequence analysis revealed that it shared 99.0% homology with the protist Pseudobodo tremulans. Scanning electron microscope analysis showed that Pseudobodo sp cells were approximately 4-5 μm long, biflagellate with an anterior collar around the anterior part of the cell in unstressed feeding cells. The lytic activity relates to a sub-cellular fraction that is blocked on a 0.22 μm filter because the lytic activity was lost after its lysates were filtered through 0.22 μm membranes. Besides the initial host, Pseudobodo sp KD51 could also kill other algae, indicating its relatively wide inhibitory spectrum. Heat stability, pH and salinity tolerance were tested to understand its inhibitory activities, and the results showed that it was heat-sensitive, and pH and salinity tolerant. | |||
| TO cite this article:Chen Zhangran,Lei Xueqian,Zhang Jingyan, et al. Pseudobodo sp, a new pathogen for a potential energy-producing algae: Chlorella vulgaris cultures[OL].[28 November 2013] http://en.paper.edu.cn/en_releasepaper/content/4571332 | |||
| 2. Molecular Cloning, Characterization, and Dye-Decolorizing Ability of a Laccase from Bacillus subtilis X1 | |||
| GUAN Zhengbing,ZHANG Ning,SONG Chenmeng,LIAO Xiangru | |||
| Biology 16 October 2013 | |||
| Show/Hide Abstract | Cite this paper︱Full-text: PDF (0 B) | |||
| Abstract:Laccases from fungal origin are typically unstable at high temperatures and alkaline conditions. This characteristic limits their practical applications. In this study, a new bacterial strain exhibiting laccase activity was isolated from raw fennel honey samples and identified as Bacillus subtilis X1. The CotA-laccase gene was cloned from strain X1 and efficiently expressed in Escherichia coli in a biologically active form. The purified recombinant laccase demonstrated an extensive pH range for catalyzing substrates and high stability toward alkaline pH and high temperatures. No loss of laccase activity was observed at pH 9.0 after 10 d of incubation, and approximately 21% of the initial activity was detected after 10 h at 80 C. Two anthraquinonic dyes (reactive blue 4 and reactive yellow brown) and two azo dyes (reactive red 11 and reactive brilliant orange) could be partially decolorized by purified laccase in the absence of a mediator. The decolorization process was efficiently promoted when methylsyringate was present, with more than 90% of color removal occurring in 3 h at pH 7.0 or pH 9.0. These unusual properties indicated a high potential of the novel CotA-laccase for industrial applications. | |||
| TO cite this article:GUAN Zhengbing,ZHANG Ning,SONG Chenmeng, et al. Molecular Cloning, Characterization, and Dye-Decolorizing Ability of a Laccase from Bacillus subtilis X1[OL].[16 October 2013] http://en.paper.edu.cn/en_releasepaper/content/4564243 | |||
| 3. A soil-dwelling pseudomonas sp.593 harboring an exogenous hrpZ gene elicits a typical hypersensitive response in tobacco and soybean leaves | |||
| Long Deliang,He Huoguang,Xiong Min,Li Yang,Wu Wenhua,Wang Xingguo | |||
Biology 13 April 2013
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| Abstract: Pseudomonas sp.593 is a soil-dwelling bacterium unable to elicit any hypersensitive response (HR) in tobacco or soybean . The hrpZ gene，encoding an abundant type III secretion system (T3SS) dependent protein, was cloned from a phytopathogen Pseudomonas syringae pv. Syringae van Hall CFCC 1336. The HrpZ harpin expressed in E. coli was purified to homogeneity, and used to raise polyclonal anti-HrpZ rabbit serum. The cloned hrpZ gene was then introduced into the soil bacterium Pseudomonas sp.593 via transformation of the plasmid pMEK-hrpZ. Western blotting and HR assay showed that the hrpZ-transformed Pseudomonas sp.593 was not only able to secret HrpZ harpin but also elicited a strong HR reaction in tobacco and soybean just as P. syringae did. In addition, bacterial cells were able to grow and multiply in the HR zone. Our results demonstrate that an avirulent strain can become a virulent-like pathogen, or a pathogen strain can broaden its host range once a single exogenous hrpZ gene cloned from a phytopathogen is introduced into a bacterium displaying phylogenetic diversity. | |||
| TO cite this article:Long Deliang,He Huoguang,Xiong Min, et al. A soil-dwelling pseudomonas sp.593 harboring an exogenous hrpZ gene elicits a typical hypersensitive response in tobacco and soybean leaves[J]. | |||
| 4. The tetraspanin gene MaPls1 contributes to virulence by affecting germination, appressorial function and enzymes for cuticle-degradation in the entomopathogenic fungus, Metarhizium acridium | |||
| LUO Sha,HE Min,CAO Yueqing,XIA Yuxian | |||
| Biology 25 March 2013
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| Abstract:Tetraspanins regulate cellular activities through association with other components on membrane in most eukaryote. The tetraspanin Pls1 controls an appressorial-mediated penetration in phytopathogenic fungi. However, the mode of regulation and signal pathways that Pls1 involved in are not clear. In this study, a Pls1 gene (MaPls1) was functionally characterized in the entomopathogenic fungus Metarhizium acridum. MaPls1 was highly expressed in mycelium and appressorium, and accumulated on the plasma membrane or inside the cytoplasm. The ΔMaPls1 had a delayed germination and appressorium formation and impaired turgor pressure on locust wing, but a normal vegetative growth and conidiation on medium. Bioassays showed that ΔMaPls1 had a decreased virulence and hyphal body formation in hemolymph when conidia were topically inoculated, but had no difference from wild type when the insect cuticle was bypassed. Moreover, the ability of breaching the cuticle from insect inside was impaired. Digital Gene Expression analysis between the ΔMaPls1 and wild type revealed that genes involved in hydrolyzing host cuticle and cell wall synthesis and remodeling were dramatically down-regulated. MaPls1 participated in a wide crosstalk with other signal pathways, including calmodulin-dependent pathway, and GTPase and cAMP-PKA etc. Taken together, these results demonstrated the important roles of MaPls1 at the early stage of infection-associated development in M. acridum. | |||
| TO cite this article:LUO Sha,HE Min,CAO Yueqing, et al. The tetraspanin gene MaPls1 contributes to virulence by affecting germination, appressorial function and enzymes for cuticle-degradation in the entomopathogenic fungus, Metarhizium acridium[OL].[25 March 2013] http://en.paper.edu.cn/en_releasepaper/content/4532163 | |||
| 5. Tenacibaculum yunxiaonensis sp. nov., is an algicidal speices | |||
| Li Yi,Zheng Wei,Zheng Tianling | |||
| Biology 19 March 2013 | |||
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| Abstract:In an attempt to investigate the algicidal bacteria in coastal seawater of Yunxiao county where red tides outbreak frequently, many bacterial strains were isolated and characterized taxonomically. This study focuses on one of these isolates, designated strain 1C-3T, with algicidal activity against the harmful algal species Phaeodactylum tricornutum. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 1C-3T fell within the genus Tenacibaculum and was most closely associated with Tenacibaculum aestuarii SMK-4T, with which the isolate exhibited 96.7 % 16S rRNA gene sequence similarity, lower similarities were shown to other members of the genus Tenacibaculum (<96.2 %). The strain formed a distinct lineage with species T. litopenaei B-IT (96.0 %), T. geojense YCS-6T (94.5 %) and T. jejuense CNURIC 013T (95.4 %). Growth was observed at temperatures from 16 to 38 C, at salinities from 2 to 4 % and at pH from 6 to 9. The major fatty acids were summed feature 3 (C16:1 ω6c and/or C16:1 ω7c), iso-C17:0 3-OH, iso-C15:0 and iso-C15:0 3-OH. The DNA G+C content of the strain was 33.2 mol% and the major respiratory quinone was menaquinone-6 (MK-6). Differential phenotypic properties and phylogenetic distinctiveness in this study distinguished strain 1C-3T from all other members of the genus Tenacibaculum. According to its morphology, physiology, fatty acid composition and 16S rRNA gene sequence data, strain 1C-3T represents a novel species in genus Tenacibaculum, for which the name Tenacibaculum yunxiaonensis sp. nov. is proposed. The type strain is 1C-3T. | |||
| TO cite this article:Li Yi,Zheng Wei,Zheng Tianling. Tenacibaculum yunxiaonensis sp. nov., is an algicidal speices[OL].[19 March 2013] http://en.paper.edu.cn/en_releasepaper/content/4527893 | |||
| 6. Development of a single nucleotide polymorphism (SNP) DNA Microarray for Detection and Genotyping of SARS Coronavirus | |||
| GUO Xi,LIU Bin | |||
Biology 24 January 2013
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| Abstract:A novel coronavirus, severe acute respiratory syndrome coronavirus (SARS-CoV), has been identified as the causative agent of severe acute respiratory syndrome. It has been known that the spike (S) glycoprotein is required for both viral attachment to its permissive cells and fusion of the viral envelope with the host cell membrane. There are 27 single nucleotide variations(SNVs) in the s gene encoding for the spike glycoprotein which are maybe related to the epidemic of this virus[10]. In our study, a SNP detecting microarray system including 108 probes was developed and the utility of this system was demonstrated in the parallel analysis of 25 point mutations from s gene. The efficiency and specificity of this microarray was evaluated by analysis of 20 samples and the veracity was 95%, this result showed that our microarray may be a promising tool for SARS-CoV detection and genotyping and analysis of its prevalence. | |||
| TO cite this article:GUO Xi,LIU Bin. Development of a single nucleotide polymorphism (SNP) DNA Microarray for Detection and Genotyping of SARS Coronavirus[OL].[24 January 2013] http://en.paper.edu.cn/en_releasepaper/content/4517710 | |||
| 7. Development of the specific DNA-typing method for Escherichia coli O156 serogroup | |||
| GUO Xi,LIU Bin | |||
| Biology 10 January 2013 | |||
| Show/Hide Abstract | Cite this paper︱Full-text: PDF (0 B) | |||
| Abstract:Escherichia coli O156 strains are frequently isolated from diarrheic and healthy animals and always express intimin, which is a virulence-associated factor and required for the formation of attaching-effacing (AE) lesions. The O antigen gene cluster of E. coli O156 type strain was sequenced, and 16 open reading frames were assigned functions on the basis of homology. The identity of the putative wzy gene was confirmed by comparison of LPS phenotypes between a wzy deficient mutant and the wild type of E.coli O156. By screening against 186 E. coli and Shigella type strains, two genes specific for E. coli O156 were identified. A PCR assay based on the specific genes were developed and tested on 10 clinical and environmental isolates of O156 and 20 isolates of other serogroups in a double-blind test. The sensitivity of the PCR assay was also determined, and as little as 1.92 pg per μl of chromosomal DNA and as few as 0.1 CFU per g of contaminated beef and water samples can be detected. The PCR assay developed in this study can be used for detection and identification of E.coli O156 strains from environmental samples rapidly and accurately, and it is especially useful when dealing with large number of samples. | |||
| TO cite this article:GUO Xi,LIU Bin. Development of the specific DNA-typing method for Escherichia coli O156 serogroup[OL].[10 January 2013] http://en.paper.edu.cn/en_releasepaper/content/4513807 | |||
| 8. Anti-biofilm Activity of Resveratrol and Ursolic Acid Against MRSA Pathogens in Vitro | |||
| TAN Xiaojuan,YANG Dongting,QIN Nan,HUANG Zongjun,JIA Aiqun | |||
| Biology 09 January 2013 | |||
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| Abstract:Methicillin-resistant Staphylococcus aureus (MRSA) is one of main pathogens of medical device-related infections due to its adhesion and biofilm-forming capacity on the organ surfaces of host. Traditional antibiotic therapy is only able to eliminate planktonic cells, leaving the sessile forms to propagate within the biofilm and continue to disseminate when therapy is terminated. Recently, some quorum sensing inhibitors (QSIs) could be an alternative tool to suppress the emergence and the spread of these organisms by inhibiting or removing the bacterial biofilm. Here, we found that two isolated natural compounds in our group, TUE-1 and TUE-2, could block biofilm formation of MRSA. Although the inhibiting effects of ursolic acid and resveratrol on planktonic bacteria have been investigated in a few studies, their capacities of inhibiting biofilm formation or removing mature biofilm of MRSA have not been reported to date. In this study, in vitro viability assays of biofilm were performed that TUE-2 at 30μg/ml and TUE-1 at 100μg/ml inhibited biofilm formation of MRSA with 18h incubation time, and TUE-1 at 150μg/ml may partly remove established biofilm. Although the mechanisms of inhibiting biofilm formation and disrupting mature biofilm by TUE-1 and TUE-2 are not fully understood, data investigated here indicated a potential application for TUE-1 and TUE-2 as adjuvant therapeutic agents for the prevention of biofilm-related infection. | |||
| TO cite this article:TAN Xiaojuan,YANG Dongting,QIN Nan, et al. Anti-biofilm Activity of Resveratrol and Ursolic Acid Against MRSA Pathogens in Vitro[OL].[ 9 January 2013] http://en.paper.edu.cn/en_releasepaper/content/4512794 | |||
| 9. Cloning of the gene encoding endo-1, 4-β-mannosidase from Bacillus subtilis HB002 and expression in Pichia pastoris | |||
| FU Lin,ZHAI Chao,KANG Lixin,MA Lixin | |||
| Biology 12 November 2012
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| Abstract:Endo-1, 4-β-mannosidase (E.C. 3.2.1.78), which is also called mannanase, catalyzes the random hydrolysis of β-1, 4-mannosidic linkages in the main chain of mannan and its heteropolysaccharides. Therefore, mannanases are widely applied not only in researches, but also in industries. Mannanases can be produced by various organisms, including bacteria, fungi, plants, and as well as animals. Bacillus subtilis is a major source of this enzyme. A gene from Bacillus subtilis HB002 coding an endo-1, 4-β-mannosidase belonging to glycoside hydrolyase family 26 (GH26), was first cloned from the genome with shot-gun method and the enzyme was heterogenously expressed in Pichia pastoris GS115, driven by a mutant of AOX1 promoter, the d1+2x201 AOX1 and the MF4I signal peptide. The expression of this enzyme was confirmed by SDS-PAGE and plate assay. The molecular weight of the recombinant protein is about 42 kDa. The expression of target protein is up to 0.25mg/mL and the enzyme activity is about 222 U/mL. According to the analysis of enzyme characteristics, the optimal pH is between pH5.6-7.0 and the optimal temperature is 55 C when locust bean gum is used as substrate. This enzyme is fairly stable at various pH and temperature. Accordingly, it is still stable at pH5.0 to 7.0 after incubation at room temperature for 5h. The enzyme remains about 95% activity after 10h incubated at 50 C. In addition, it shows strong substrate specificity to galactomannans and konjac powder. The enzyme activity is strongly inhibited by Co2+ and Mn2+, but it is not sensitive to other ions. Analysis of hydrolytic products by thin layer chromatography (TLC) and MALDI-MS revealed that the degrees of polymerization of products are mostly less than 13, which indicated it's suitable for animal feed and industry. This study is the first report on the cloning, and heterogenous expression of an endo-1, 4-β-mannosidase from Bacillus subtilis HB002 in Pichia pastoris. In addition, the expression level of this endo-1, 4-β-mannosidase increases dramatically when the AOX1 promoter and α-mating factor signal of Sacchromyces cerevisiae in the Pichia pastoris expression system are replaced with the combination of d1+2x201 AOX1 promoter and the MF4I signal peptide coding sequence, respectively. This improvement implies a potential of its application in large-scale. | |||
| TO cite this article:FU Lin,ZHAI Chao,KANG Lixin, et al. Cloning of the gene encoding endo-1, 4-β-mannosidase from Bacillus subtilis HB002 and expression in Pichia pastoris[OL].[12 November 2012] http://en.paper.edu.cn/en_releasepaper/content/4492023 | |||
| 10. MaHog1, a Hog1-type MAP kinase gene, contributes to stress tolerance and virulence of the entomopathogenic fungus, Metarhizium acridum | |||
| Jin Kai,Ming Yue,Xia Yuxian | |||
| Biology 03 September 2012
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| Abstract:Fungal biocontrol agents have great potential in integrated pest management. However, the poor efficacy and secnsitiveness to various adversities have hampered their wide application. In eukaryotic cells, Hog1 kinase play a critical role in stress responses. In this study, MaHog1 (GenBank accession number EFY85878) encodeing a member of the Hog1/Sty1/p38 MAPK family was identified from M. acridum. Targeted gene disruption was adopted to analyze the role of MaHog1 in virulence and tolerance to adverse factors. Mutant depleted for MaHog1 showed increased sensitivity to high osmotic stress, high temperature and oxidative stress and exhibited remarkable resistance to the cell wall disturbing agents. These results suggested that Hog1 kinase has conserved function in regulating multistress responses among fungi, and that MaHog1 might influence the cell wall biogenesis in M. acridum. Bioassays conducted with topical inoculation and intrahaemocoel injection revealed that MaHog1 is required for both the penetration and the postpenetration development of M. acridum. Disruption of MaHog1 resulted in a signi?cant reduction in virulence, likely due to the combination of a decrease in conidial germination, a reduction in appressorium formation, and a decline in growth rate in insect haemolymph, which might be caused by impairing the fungal tolerance to various stresses during infection. | |||
| TO cite this article:Jin Kai,Ming Yue,Xia Yuxian. MaHog1, a Hog1-type MAP kinase gene, contributes to stress tolerance and virulence of the entomopathogenic fungus, Metarhizium acridum[OL].[ 3 September 2012] http://en.paper.edu.cn/en_releasepaper/content/4488394 | |||
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