RESULTS:
1 - 12 of 12 for "Shan Li"
An improved reverse genetics system for rotavirus vaccine strain LLR using five plasmid vectors
Species A rotaviruses (RVs) which belong to the family Sedoreoviridae and contain a genome of 11 segmented dsRNA segments are a leading cause of severe acute gastroenteritis in infants and children younger than 5 years of age. We previously developed a strategy to recover rotavirus vaccine strain LLR from 11 cloned plasmids. Here we report an improved reverse genetics system for LLR by combining two or three transcriptional cassettes in a single plasmid which substantially enhances rescue efficiency from 66.7% (8/12) to 91.7 % (11/12). Furthermore the recombinant LLR stably expressing NLuc was rescued based on the five-plasmid reverse genetics system. Improvements to the rotavirus reverse genetics system will enhance its applicability for studies of rotavirus biology and clinical use.
Ectobacillus ponti sp. nov., a novel bacterium isolated from Pearl River Estuary
A Gram-staining-positive aerobic motile and rod-shaped strain designated SYSU M60031T was isolated from a Pearl River Estuary sediment sample Guangzhou Guangdong China. The isolate could grow at pH 5.0–8.0 (optimum pH 7.0) 25–37 °C (optimum 28 °C) and in the presence of 0–1 % (w/v) NaCl (optimum 0 %). The predominant respiratory menaquinone of SYSU M60031T was MK-7. The cellular polar lipids were diphosphatidylglycerol phosphatidylethanolamine phosphatidylglycerol one unidentified aminophospholipid and one unidentified aminolipid. The major fatty acids (>10 % of total) were iso-C14 : 0 iso-C15 : 0 anteiso-C15 : 0 iso-C16 : 0 and C16 : 0. The genomic DNA G+C content was 51.2 %. Phylogenetic analyses based on 16S rRNA gene sequences and core genes indicated that strain SYSU M60031T belonged to the genus Ectobacillus and showed the highest sequence similarity to Ectobacillus funiculus NAF001T (96.16%) followed by Ectobacillus antri SYSU K30001T (95.08 %). Based on the phenotypic genotypic and phylogenetic data strain SYSU M60031T should be considered to represent a novel species of the genus Ectobacillus for which the name Ectobacillus ponti sp. nov. is proposed. The type strain of the proposed novel isolate is SYSU M60031T (=CGMCC 1.19243T =NBRC 115614T).
Berberine at sub-inhibitory concentration inhibits biofilm dispersal in Staphylococcus aureus
Staphylococcus aureus is a major human pathogen which has multiple drug resistance and can cause serious infections. Recent studies have shown that berberine has antibacterial activity and it can affect biofilm formation of S. aureus . However the berberine effect on the biofilm of S. aureus is controversial. In this study we investigate the effect of berberine on the biofilm development in S. aureus NCTC8325 and explore the possible mechanism. Susceptibility test shows that berberine inhibits growth of methicillin-sensitive S. aureus (MSSA) methicillin-resistant S. aureus (MRSA) and vancomycin-intermediate S. aureus (VISA) at different concentrations. S. aureus NCTC8325 is chosen as a model strain to explore further the berberine effect. The MIC of berberine for S. aureus NCTC8325 is 256 µg ml−1. Berberine below 32 µg ml−1 inhibits the dispersal of biofilm and stimulates clumping of cells of NCTC8325 in a concentration-dependent manner while not showing obvious inhibition on the bacterial growth. The transcription of the key negative regulator of biofilm dispersal AgrA is decreased and an agrA mutant forms biofilm reaching to a similar level of biomass to WT in the presence of berberine at 32 µg ml−1. Transcription of some genes involving synthesis of biofilm structure components including polysaccharide intracellular adhesin (PIA) proteins and eDNA were also up-regulated especially icaA for PIA synthesis. And consistently PIA content was increased in cells exposed to berberine at 32 µg ml−1. This study reveals the dependence of berberine inhibition of biofilm dispersal on the Agr system which is the first report exploring the molecule mechanism of the berberine effect on the biofilm of S. aureus .
Roseomonas ponticola sp. nov., a novel bacterium isolated from Pearl River estuary
A novel species of the genus Roseomonas designated SYSU M41301T was isolated from water sample of the Pearl River estuary in Guangdong China. Polyphasic taxonomic and phylogenomic analyses were used to determine the taxonomy position of the strain. Phylogenetic analysis using 16S rRNA gene sequence indicated that strain SYSU M41301T showed the highest sequence similarity to Roseomonas stagni KCTC 22213T (97.9 %) and Roseomonas riguiloci KCTC 23339T (96.4 %). The novel species could be differentiated from other species of the genus Roseomonas by its distinct phenotypic and genotypic characteristics. The isolate was Gram-staining-negative aerobic short rod-shape oxidase-positive and non-motile. The predominant respiratory quinone was ubiquinone 8 (Q-8). The major polar lipids were diphosphatidylglycerol phosphatidylethanolamine phosphatidylglycerol phosphatidylcholine and one unidentified polar lipid. The major fatty acids (>10 % of total) were 11-methyl C18 : 1 ω7c summed feature 3 (C16 : 1 ω7c and/ or C16 : 1 ω6c) and summed feature 8 (C18: :1 ω7c and/or C18 : 1 ω6c). The G+C content of the novel isolate based on genomic DNA was 72.0 mol%. On the basis of phenotypic genotypic and phylogenetic data strain SYSU M41301T should be considered to represent a novel species in the genus Roseomonas for which the name Roseomonas ponticola sp. nov. is proposed with the type strain SYSU M41301T (=KCTC 72726T=CGMCC 1.18613T).
Sphingobacterium chungjuense sp. nov., isolated from a freshwater lake
A Gram-stain-negative rod-shaped aerobic non-flagellated chemoheterotrophic bacterium designated strain IMCC25678T was isolated from an artificial freshwater reservoir Chungju Lake in the Republic of Korea. The 16S rRNA gene sequence analysis indicated that strain IMCC25678T belongs to the genus Sphingobacterium with ≤98.7 % sequence similarities to Sphingobacterium species. Whole genome sequencing of strain IMCC25678T revealed a 3.9 Mbp genome size with a DNA G+C content of 42.2 mol%. The IMCC25678T genome shared ≤89.7 % average nucleotide identity and ≤21.4 % digital DNA–DNA hybridization values with closely related species of the genus Sphingobacterium indicating that the strain represents a novel species. Summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c) iso-C15 : 0 and iso-C17 : 0 3-OH were found to be the predominant cellular fatty acid constituents in the strain. The major respiratory quinone was MK-7. The major polar lipids were phosphatidylethanolamine one unidentified phosphoglycolipid one unidentified sphingolipid and three unidentified polar lipids. Based on the phylogenetic and phenotypic characteristics strain IMCC25678T was considered to represent a novel species within the genus Sphingobacterium for which the name Sphingobacterium chungjuense sp. nov. is proposed. The type strain is IMCC25678T (=KACC 19485T=NBRC 113130T).
Leeia aquatica sp. nov., isolated from freshwater
A Gram-stain-negative rod-shaped obligately aerobic motile by a single polar flagellum chemoheterotrophic bacterium designated strain IMCC25680T was isolated from surface water in Chungju Lake Republic of Korea. 16S rRNA gene sequence analysis revealed that strain IMCC25680T was most closely related to Leeia oryzae HW7T with 95.5% sequence similarity and formed a robust clade with L. oryzae HW7T. Whole genome sequencing showed that strain IMCC25680T had a genome 3.6 Mbp long with 60.7 mol% DNA G+C content. Average nucleotide identity and digital DNA–DNA hybridization values between strain IMCC25680T and L. oryzae HW7T were 72.4% and 18.5% respectively indicating that the novel strain represents a novel species of the genus Leeia . The major cellular fatty acids of strain IMCC25680T were iso-C16:0 and summed feature 3 (comprising C16:1 ω6c and/or C16:1 ω7c). The respiratory quinone detected in the strain was ubiquinone-8. The major polar lipids were found to be phosphatidylethanolamine phosphatidylglycerol diphosphatidylglycerol and two unidentified polar lipids. On the basis of the phylogenetic and phenotypic characterization strain IMCC25680T was considered to represent a novel species within the genus Leeia for which the name Leeia aquatica sp. nov. is proposed. The type strain is IMCC25680T (=KACC 19487T =NBRC 113132T).
Halioglobus maricola sp. nov., isolated from coastal seawater
A Gram-stain-negative rod-shaped aerobic non-flagellated chemoheterotrophic bacterium designated IMCC14385T was isolated from surface seawater of the East Sea Republic of Korea. The 16S rRNA gene sequence analysis indicated that IMCC14385T represented a member of the genus Halioglobus sharing 94.6–97.8 % similarities with species of the genus. Whole-genome sequencing of IMCC14385T revealed a genome size of 4.3 Mbp and DNA G+C content of 56.7 mol%. The genome of IMCC14385T shared an average nucleotide identity of 76.6 % and digital DNA–DNA hybridization value of 21.6 % with the genome of Halioglobus japonicus KCTC 23429T. The genome encoded the complete poly-β-hydroxybutyrate biosynthesis pathway. The strain contained summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c) summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) and C17 : 1 ω8c as the predominant cellular fatty acids as well as ubiquinone-8 (Q-8) as the respiratory quinone. The polar lipids detected in the strain were phosphatidylethanolamine phosphatidylglycerol diphosphatidylglycerol five unidentified phospholipids an unidentified aminolipid an unidentified aminophospholipid and four unidentified lipids. On the basis of taxonomic data obtained in this study it is suggested that IMCC14385T represents a novel species of the genus Halioglobus for which the name Halioglobus maricola sp. nov. is proposed. The type strain is IMCC14385T (=KCTC 72520T=NBRC 114072T).
Group 16SrXI phytoplasma strains, including subgroup 16SrXI-B and a new subgroup, 16SrXI-D, are associated with sugar cane white leaf
Sugar cane white leaf (SCWL) is a serious disease caused by phytoplasmas. In this study we performed nested PCR with phytoplasma universal primer pairs (P1/P7 and R16F2n/R16R2) for the 16S rRNA gene to detect SCWL phytoplasmas in 31 SCWL samples collected from Baoshan and Lincang Yunnan China. We cloned and sequenced the nested PCR products revealing that the 16S rRNA gene sequences from 31 SCWL samples were all 1247 bp in length and shared more than 99 % nucleotide sequence similarity with the 16S rRNA gene sequences of SCWL phytoplasmas from various countries. Based on the reported 16S rRNA gene sequence data from SCWL isolates of various countries we conducted phylogenetic and virtual RFLP analysis. In the resulting phylogenetic tree all SCWL isolates clustered into two branches with the Lincang and Baoshan SCWL phytoplasma isolates belonging to different branches. The virtual RFLP patterns show that phytoplasmas of the Lincang branch belong to subgroup 16SrXI-B. However the virtual RFLP patterns revealed by HaeIII digestion of phytoplasmas of the Baoshan branch differed from those of subgroup 16SrXI-B. According to the results of phylogenetic and virtual RFLP analysis we propose that the phytoplasmas of the Baoshan branch represent a new subgroup 16SrXI-D. These findings suggest that SCWL is caused by phytoplasmas from group 16SrXI including subgroup 16SrXI-B and a new subgroup 16SrXI-D.
Phytoactinopolyspora endophytica gen. nov., sp. nov., a halotolerant filamentous actinomycete isolated from the roots of Glycyrrhiza uralensis F.
A novel endophytic actinomycete designated strain EGI 60009T was isolated from the roots of Glycyrrhiza uralensis F. collected from Xinjiang Province north-west China. The isolate was able to grow in the presence of 0–9 % (w/v) NaCl. Strain EGI 60009T had particular morphological properties: the substrate mycelia fragmented into rod-like elements and aerial mycelia differentiated into short spore chains. ll-2 6-Diaminopimelic acid was the cell-wall diamino acid and rhamnose galactose and glucose were the cell-wall sugars. MK-9(H4) was the predominant menaquinone. The major fatty acids of strain EGI 60009T were iso-C15 : 0 anteiso-C15 : 0 anteiso-C17 : 0 iso-C17 : 0 iso-C17 : 1 and I/anteiso-C17 : 0 B. Mycolic acids were absent. The DNA G+C content of strain EGI 60009T was 70.4 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain EGI 60009T belongs to the family Jiangellaceae and formed a distinct clade in the phylogenetic tree. 16S rRNA gene sequence similarities between strain EGI 60009T and other members of the genera Jiangella and Haloactinopolyspora were 96.1–96.4 and 95.7–96.0 % respectively. Based on these results and supported by morphological physiological and chemotaxonomic data and numerous phenotypic differences a novel species of a new genus Phytoactinopolyspora endophytica gen. nov. sp. nov. is proposed. The type strain of Phytoactinopolyspora endophytica is EGI 60009T ( = KCTC 29657T = CPCC204078T).
Rufibacter roseus sp. nov., isolated from radiation-polluted soil
A rose Gram-stain-negative aerobic rod-shaped bacterium that was motile by gliding and designated strain H359T was isolated from radiation-polluted soil (with high Cs137) from the Xinjiang Uygur Autonomous Region of PR China and subjected to a polyphasic taxonomic analysis. The isolate grew optimally at 30 °C and pH 7.0. It grew with NaCl up to 4 % (w/v). 16S rRNA gene sequence analysis indicated that strain H359T belonged to the genus Rufibacter a member of the family Cytophagaceae with Rufibacter tibetensis CCTCC AB 208084T as its closest phylogenetic relative having 96.1 % 16S rRNA gene sequence similarity to the type strain. Strain H359T contained menaquinone-7 (MK-7) as the predominant menaquinone and the major fatty acids were iso-C15 : 0 summed feature 4 (iso-C17 : 1 I and/or anteiso-C17 : 1 B) summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 1ω5c. The polar lipid profile had phosphatidylethanolamine as the major component. The DNA G+C content was 43.9 mol%. Based on phenotypic genotypic and phylogenetic evidence strain H359T represents a novel species of the genus Rufibacter for which the name Rufibacter roseus sp. nov. is proposed. The type strain is H359T ( = CPCC 100615T = KCTC 42217T).
The pleitropic regulator AdpAch is required for natamycin biosynthesis and morphological differentiation in Streptomyces chattanoogensis
The complete natamycin (NTM) biosynthetic gene cluster of Streptomyces chattanoogensis was cloned and confirmed by the disruption of pathway-specific activator genes. Comparative cluster analysis with its counterpart in Streptomyces natalensis revealed different cluster architecture between these two clusters. Compared with the highly conserved coding sequences sequence variations appear to occur frequently in the intergenic regions. The evolutionary change of nucleotide sequence in the intergenic regions has given rise to different transcriptional organizations in the two clusters and resulted in altered gene regulation. These results provide insight into the evolution of antibiotic biosynthetic gene clusters. In addition we cloned a pleitropic regulator gene adpAch in S. chattanoogensis. Using the genetic system that we developed for this strain adpAch was deleted from the genome of S. chattanoogensis. The ΔadpAch mutant showed a conditionally sparse aerial mycelium formation phenotype and defects in sporulation; it also lost the ability to produce NTM and a diffusible yellow pigment normally produced by S. chattanoogensis. RT-PCR analysis revealed that transcription of adpAch was constitutive in YEME liquid medium. By using rapid amplification of 5′ complementary DNA ends two transcription start sites were identified upstream of the adpAch coding region. Quantitative transcriptional analysis showed that the expression level of the NTM regulatory gene scnRI decreased 20-fold in the ΔadpAch mutant strain while the transcription of the other activator gene scnRII was not significantly affected. Electrophoretic mobility shift assay (EMSA) showed that AdpAch binds to its own promoter but fails to bind to the promoter region of scnRI indicating that the control of scnRI by AdpAch is exerted in an indirect way. This work not only provides a platform and a new potential target for increasing the titre of NTM by genetic manipulation but also advances the understanding of the regulation of NTM biosynthesis.
Origin and evolutionary characteristics of antigenic reassortant influenza A (H1N2) viruses isolated from man in China
During the 1988/1989 influenza season five antigenic reassortant influenza A (H1N2) viruses not previously isolated from man were isolated in Hebei province People’s Republic of China. All isolates contained haemagglutinins (HAs) and neuraminidases (NAs) which were antigenically similar to those of the recent Russian (H1N1) and Hong Kong influenza A (H3N2) viruses respectively. The results of antigenic and nucleotide sequence analyses revealed that the genes encoding the polymerase nucleoprotein NA matrix and non-structural proteins of the reassortant A/Hebei/24/89 (H1N2) virus were derived from the H3N2 parent virus whereas its HA gene was from the H1N1 parent virus. The nucleotide sequences of the HA (encoding the HA1 subunit) and NA genes of the reassortant viruses were also determined. Phylogenetic trees constructed from these data by the neighbour-joining method revealed that the HA gene of the reassortant virus was closely related to those of recent human H1N1 viruses whereas the NA gene was related to a recent human Hong Kong (H3N2) virus lineage.