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1.
Phytopathology ; 109(7): 1115-1128, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30829555

RESUMO

Potato scab, a serious soilborne disease caused by Streptomyces spp., occurs in potato-growing areas worldwide and results in severe economic losses. In this paper, the pathogenicity of Streptomyces strain AMCC400023, isolated from potato scabs in Hebei Province, China, was verified systematically by the radish seedling test, the potato tuber slice assay, the potted back experiment, and the detection of phytotoxin thaxtomin A. Morphological, physiological, and biochemical characteristics were determined, and the 16S ribosomal RNA analyses of Streptomyces sp. AMCC400023 were carried out. To obtain the accurate taxonomic status of the pathogen strain, the whole genome was sequenced, and the phylogenetic tree among 31 Streptomyces genomes was formed. The average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) were analyzed, and at the same time, the toxicity-related genes between Streptomyces sp. AMCC400023 and Streptomyces scabiei were compared, all based on the whole-genome level. All of the data supported that, instead of a member of S. scabiei, test strain Streptomyces sp. AMCC400023 was a distinct phytopathogen of potato common scab, which had a relatively close relationship with S. scabiei while separating clearly from S. scabiei at least in the species level of taxonomic status. The complete pathogenicity island (PAI) composition of Streptomyces sp. AMCC400023 was identified, which contained a toxin region and a colonization region. It was conjectured that the PAI of Streptomyces sp. AMCC400023 might be directly or indirectly acquired from S. scabiei 87-22 by horizontal gene transfer, or at the very least, there was a very close homologous relationship between the two pathogens as indicated by a series of analyses, such as phylogenetic relationships among 31 Streptomyces species, ANI and isDDH analyses, PAI structure mapping, thaxtomin A synthetic gene cluster tree construction, and most important, the collinearity analysis at the genome level.


Assuntos
Ilhas Genômicas/genética , Doenças das Plantas/microbiologia , Solanum tuberosum , Streptomyces , China , Genômica , Filogenia , Solanum tuberosum/microbiologia , Streptomyces/patogenicidade
2.
Microbiome ; 7(1): 14, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30709420

RESUMO

BACKGROUND: Soil microorganisms can mediate the occurrence of plant diseases. Potato common scab (CS) is a refractory disease caused by pathogenic Streptomyces that occurs worldwide, but little is known about the interactions between CS and the soil microbiome. In this study, four soil-root system compartments (geocaulosphere soil (GS), rhizosphere soil (RS), root-zone soil (ZS), and furrow soil (FS)) were analyzed for potato plants with naturally high (H) and low (L) scab severity levels. We aimed to determine the composition and putative function of the soil microbiome associated with potato CS. RESULTS: The copy numbers of the scab phytotoxin biosynthetic gene txtAB and the bacterial 16S rRNA gene as well as the diversity and composition of each of the four soil-root system compartments were examined; GS was the only compartment that exhibited significant differences between the H and L groups. Compared to the H group, the L group exhibited a lower txtAB gene copy number, lower bacterial 16S copy number, higher diversity, higher co-occurrence network complexity, and higher community function similarity within the GS microbiome. The community composition and function of the GS samples were further revealed by shotgun metagenomic sequencing. Variovorax, Stenotrophomonas, and Agrobacterium were the most abundant genera that were significantly and positively correlated with the scab severity level, estimated absolute abundance (EAA) of pathogenic Streptomyces, and txtAB gene copy number. In contrast, Geobacillus, Curtobacterium, and unclassified Geodermatophilaceae were significantly negatively correlated with these three parameters. Compared to the function profiles in the L group, several genes involved in "ABC transporters," the "bacterial secretion system," "quorum sensing (QS)," "nitrogen metabolism," and some metabolism by cytochrome P450 were enriched in the H group. In contrast, some antibiotic biosynthesis pathways were enriched in the L group. Based on the differences in community composition and function, a simple model was proposed to explain the putative relationships between the soil microbiome and CS occurrence. CONCLUSIONS: The GS microbiome was closely associated with CS severity in the soil-root system, and the occurrence of CS was accompanied by changes in community composition and function. The differential functions provide new clues to elucidate the mechanism underlying the interaction between CS occurrence and the soil microbiome, and varying community compositions provide novel insights into CS occurrence.


Assuntos
Microbiota/genética , Doenças das Plantas/microbiologia , Solanum tuberosum/microbiologia , Streptomyces/classificação , Streptomyces/isolamento & purificação , Sedimentos Geológicos/microbiologia , Raízes de Plantas/microbiologia , RNA Ribossômico 16S/genética , Rizosfera , Microbiologia do Solo , Streptomyces/genética
3.
Int J Biol Macromol ; 51(1-2): 153-7, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22542852

RESUMO

Cordyceps militaris SU5-08 was derived from an initial strain (C. militaris SU5) by ultraviolet mutagenesis of protoplasts, and the extraction parameters for C. militaris SU5-08 exopolysaccharide (EPS) produced during submerged culture were optimized. The extraction rate of EPS was 1919.16±165.27 mg/l, which was 120.38±11.36% higher than that of C. militaris SU5. The in vitro scavenging effects of EPS of C. militaris SU5-08 on hydroxyl, superoxide anion and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals at a dosage of 5 g/l were 63.64±3.52%, 75.27±5.16%, and 6.46±5.03%, respectively. The reducing power of EPS of C. militaris SU5-08 was 0.21±0.01. The results suggest that the EPS of C. militaris SU5-08 can be used as a potential antioxidant which enhances adaptive immune responses.


Assuntos
Antioxidantes/farmacologia , Cordyceps/metabolismo , Polissacarídeos/farmacologia , Cordyceps/genética , Radical Hidroxila/metabolismo , Mutação , Oxirredução/efeitos dos fármacos , Polissacarídeos/isolamento & purificação , Superóxidos/metabolismo
4.
J Biosci Bioeng ; 111(1): 50-4, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20801714

RESUMO

Response surface methodology (RSM) was used to optimize the extraction parameters for Pholiota adiposa SX-02 intracellular polysaccharide (IPS) produced during submerged culture. The optimum conditions of IPS extraction were predicted to be, ultrasonic power at 564.93 W, precipitation time 30.34 h and pH 8.28, and IPS yield was estimated at 19.75%. The actual value of IPS under these conditions was 20.51%. The in vitro antioxidant results showed that the inhibition effects of IPS at a dosage of 250 mg/l on superoxide anion, hydroxyl and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical were 74.66 ± 5.31%, 69.20 ± 5.13%, and 75.20 ± 6.73%, respectively, which were 27.51 ± 2.23%, 16.58 ± 1.33%, and 9.46 ± 0.72% higher than that of butylated hydroxytoluene (BHT), respectively. The reducing power of IPS was 0.32 ± 0.02 (absorbance at 700 nm), 39.13 ± 3.47% higher than that of BHT. The results provide a reference for large-scale extraction of IPS by P. adiposa SX-02 in industrial fermentation and the IPS can be used as a potential antioxidant which enhances adaptive immune responses.


Assuntos
Depuradores de Radicais Livres/isolamento & purificação , Pholiota/metabolismo , Polissacarídeos/isolamento & purificação , Compostos de Bifenilo/metabolismo , Meios de Cultura , Depuradores de Radicais Livres/farmacologia , Concentração de Íons de Hidrogênio , Radical Hidroxila/metabolismo , Picratos/metabolismo , Polissacarídeos/farmacologia
5.
Int J Biol Macromol ; 47(2): 116-9, 2010 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-20580645

RESUMO

The extraction conditions of intracellular polysaccharide (IPS) from Pleurotus sp. mycelium in submerged culture were investigated. Four parameters affecting the IPS extraction, ultrasonic treatment time, extraction temperature, extraction time and ethanol concentration, were determined by single factor tests and then optimized by orthogonal experiments. Under the optimized conditions, the extraction rates of IPS of Pleurotus nebrodensis SJ-02, Pleurotus eryngii SI-01 and Pleurotus corncopiae SS-01 were 7.1+/-0.4%, 7.5+/-0.3%, and 8.2+/-0.5%, respectively. The in vitro hydroxyl radical inhibition percentages of IPS of three mushrooms were 32.2+/-2.8%, 16.1+/-1.5%, and 38.7+/-3.1%, respectively. The scavenging effects of IPS on superoxide anion radical and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical were 19.1+/-1.5%, 16.3+/-1.3%, 20.3+/-1.8%, 17.9+/-1.6%, 16.8+/-1.4%, and 20.5+/-1.7%, respectively. The results provide a reference for large-scale production of IPS by Pleurotus sp. in industrial fermentation.


Assuntos
Depuradores de Radicais Livres/isolamento & purificação , Depuradores de Radicais Livres/farmacologia , Espaço Intracelular/química , Micélio/citologia , Pleurotus/citologia , Polissacarídeos/isolamento & purificação , Polissacarídeos/farmacologia , Compostos de Bifenilo/metabolismo , Depuradores de Radicais Livres/metabolismo , Radical Hidroxila/metabolismo , Picratos/metabolismo , Polissacarídeos/metabolismo , Superóxidos/metabolismo
6.
Bioresour Technol ; 101(12): 4564-9, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20153962

RESUMO

Response surface methodology was used to optimize extraction parameters for Morchella esculenta SO-01 exopolysaccharide (EPS) produced during submerged culture. The optimum conditions for EPS extraction were predicted to be, concentration at 84.07 degrees C, precipitation for 22.19 h and pH 8.44, and EPS production was estimated at 5.45 g/L. The actual yield of EPS under these conditions was 5.32 g/L. The antioxidant capacity of the EPS was measured in vivo after filling the stomach with different doses of EPS and results showed that the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) of blood, spleen, liver, heart, and kidney were increased by 125%, 46.11%, 23.33%, 12.19%, 41.29%, and 63.24%, 63.12%, 166.54%, 98.01%, 57.68%, respectively, and that malonaldehyde (MDA) of blood, spleen, liver, heart, and kidney were decreased by 21.80%, 67.84%, 28.48%, 56.15%, 41.62%. The results provide a reference for large-scale extraction of EPS by M. esculenta SO-01 in industrial fermentation.


Assuntos
Agaricales/química , Antioxidantes/isolamento & purificação , Antioxidantes/farmacologia , Biotecnologia/métodos , Polissacarídeos/isolamento & purificação , Polissacarídeos/farmacologia , Análise de Variância , Animais , Glutationa Peroxidase/metabolismo , Malondialdeído/metabolismo , Camundongos , Especificidade de Órgãos/efeitos dos fármacos , Superóxido Dismutase/metabolismo
7.
Wei Sheng Wu Xue Bao ; 44(6): 729-32, 2004 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-16110948

RESUMO

Sinorhizobium meliloti XJ96077 was isolated from root nodules of alfalfa (Medicago sativa) in Xinjiang Region of China. Nodulation experiments showed that both soybean and alfalfa were effectively nodulated by XJ96077. The DNA (G+ C) mol% of strain XJ96077 was 61.9%. The DNA homologies of strain XJ96077 were 93% and 80% with S. meliloti USDA1002T and 042BM, respectively. These results showed that XJ96077 belongs to Sinorhizobium meliloti. To prove the capability of XJ96077 to nodulate both soybean and alfalfa, constitutively expressed green fluorescence protein gene gfp was introduced to XJ96077, and the recombinant strain XJ96077(G) was obtained. Root nodules of the soybean and alfalfa inoculated with XJ96077(G) and the expression of gfp were observed using the confocal laser scanning microscope. XJ96077 showed various nodulation capacities with different soybean cultivars.


Assuntos
Sinorhizobium meliloti/fisiologia , Soja/microbiologia , Simbiose , Medicago sativa/microbiologia , Fixação de Nitrogênio , Raízes de Plantas/microbiologia , Sinorhizobium meliloti/classificação
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