RESUMO
Exopolysaccharides (EPS) are macromolecules with environment beneficial properties. Currently, numerous studies focus on the absorption of heavy metals by EPS, but less attention has been paid to the effects of EPS on the plants. This study explored the effects of EPS from Lactobacillus plantarum LPC-1 on the structure and function of cell walls in rice seedling roots under cadmium (Cd) stress. The results showed that EPS could regulate the remodeling process of the cell walls of rice roots. EPS affects the synthesis efficiency and the content of the substances that made up the cell wall, and thus plays an essential role in limiting the uptake and transport of Cd in rice root. Furthermore, EPS could induce plant resistance to heavy metals by regulating the lignin biosynthesis pathway in rice roots. Finally, the cell wall remodeling induced by EPS likely contributes to plant stress responses by activating the reactive oxygen species (ROS) signaling.
Assuntos
Metais Pesados , Oryza , Oryza/metabolismo , Cádmio/metabolismo , Plântula/metabolismo , Raízes de Plantas/metabolismo , Parede Celular/metabolismo , Metais Pesados/metabolismo , Plantas/metabolismoRESUMO
Antifungalmycin 702, a new polyene macrolide antibiotic produced by Streptomycespadanus JAU4234, has a broad antifungal activity and may have potential future agricultural and/or clinical applications. However, the mechanism of antifungal action of antifungalmycin 702 remains unknown. Antifungalmycin 702 strongly inhibited mycelial growth and sclerotia formation/germination of Rhizoctonia solani. When treated with antifungalmycin 702, the hyphae morphology of R. solani became more irregular. The membrane and the cellular organelles were disrupted and there were many vacuoles in the cellular space. The lesion in the plasma membrane was detected through the increase of membrane permeability, lipid peroxidation and leakage of cell constituents. In summary, antifungalmycin 702 may exert its antifungal activity against R. solani by changing the structure of cell membranes and the cytoskeleton and interacting with the organelles.
Assuntos
Antifúngicos/farmacologia , Oryza/microbiologia , Rhizoctonia/efeitos dos fármacos , Streptomyces/metabolismo , Antibacterianos/biossíntese , Antibacterianos/química , Antibacterianos/farmacologia , Antifúngicos/química , Antifúngicos/metabolismo , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Relação Dose-Resposta a Droga , Hifas/citologia , Hifas/efeitos dos fármacos , Hifas/ultraestrutura , Macrolídeos/metabolismo , Macrolídeos/farmacologia , Testes de Sensibilidade Microbiana , Permeabilidade/efeitos dos fármacos , Doenças das Plantas/microbiologia , Polienos/metabolismo , Polienos/farmacologia , Rhizoctonia/crescimento & desenvolvimento , Rhizoctonia/ultraestruturaRESUMO
Antifungalmycin 702, a novel polyene macrolide antibiotic produced by Streptomyces padanus JAU4234, strongly inhibited mycelial growth of the rice blast fungus, Magnaporthe grisea, with EC50 of 37 µg/ml and EC90 of 136 µg/ml. Significant reduction in the number of conidia was observed at above 20 µg/ml. Conidia germination and appressorium formation were also suppressed and were not viable with >40 µg/ml. When treated with antifungalmycin 702, hyphae morphology became irregular. Based on microscopic examination, antifungalmycin 702 may exert its antifungal activity by changing the structure of cell membranes and the cytoskeleton and interacting with the organelles. Antifungalmycin 702 thus has potential as a new fungicide in the treatment of rice blast disease.
Assuntos
Fungicidas Industriais/farmacologia , Macrolídeos/farmacologia , Magnaporthe/efeitos dos fármacos , Polienos/farmacologia , Streptomyces/metabolismo , Membrana Celular/efeitos dos fármacos , Citoesqueleto/efeitos dos fármacos , Fungicidas Industriais/isolamento & purificação , Macrolídeos/isolamento & purificação , Magnaporthe/crescimento & desenvolvimento , Viabilidade Microbiana/efeitos dos fármacos , Micélio/efeitos dos fármacos , Micélio/crescimento & desenvolvimento , Organelas/efeitos dos fármacos , Oryza/microbiologia , Polienos/isolamento & purificaçãoRESUMO
Acarbose, a competitive α-glucosidase inhibitor, is clinically and widely used in the treatment of type II diabetes mellitus. In order to improve the industrial acarbose productivity by Actinoplanes sp. A56, the classical fermentation conditions such as total sugar concentration in broths, pH value and dissolved oxygen (DO) level were systematically investigated in a 30000-l fermenter, respectively. It was observed that a high-concentration total sugar (75-80 g/l), 7.0-7.2 of pH value and 40-50% of DO concentration were favorable for acarbose production. As a result, the final acarbose yield was elevated to approximately 5000 mg/l at 168 h of fermentation.
Assuntos
Acarbose/metabolismo , Fermentação/fisiologia , Microbiologia Industrial/métodos , Micromonosporaceae/metabolismo , Metabolismo dos Carboidratos , Concentração de Íons de Hidrogênio , Oxigênio , SolubilidadeRESUMO
Strain JAU4234, identified as Streptomyces padanus, was isolated from soil collected in Jiangxi Province, China. It produced actinomycin X2, fungichromin, and a new polyene macrolide compound with antifungal activity, antifungalmycin 702. Antifungalmycin 702 had good general antifungal activity and may have potential future agricultural and/or clinical applications.
Assuntos
Antifúngicos/metabolismo , Dactinomicina/análogos & derivados , Macrolídeos/metabolismo , Streptomyces/classificação , Streptomyces/metabolismo , Antifúngicos/química , Antifúngicos/isolamento & purificação , China , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Dactinomicina/química , Dactinomicina/isolamento & purificação , Dactinomicina/metabolismo , Macrolídeos/química , Macrolídeos/isolamento & purificação , Dados de Sequência Molecular , Filogenia , Polienos/química , Polienos/isolamento & purificação , Polienos/metabolismo , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Microbiologia do Solo , Streptomyces/genética , Streptomyces/isolamento & purificaçãoRESUMO
To explore the practical application value and action mechanisms of Ag-antibiotic 702 against pathogenic fungi, the inhibition spectrum of Ag-antibiotic 702 was studied by measuring the mycelium growth rate of pathogenic fungi, and the effects of Ag-antibiotic 702 on the membrane permeability of Rhizoctonia solani, a typical pathogenic fungus, were investigated, with the variations of mycelium electrolyte leakage and protein, nucleic acid, and Mg2+ and K+ contents under the action of Ag-antibiotic 702 determined, and the effects of Ag-antibiotic 702 on the cell membrane ergosterol biosynthesis and ultramicrostructure observed. The results showed that the active products of Ag-antibiotic 702 had stronger inhibition effect on 13 test pathogens, among which, Sclerotinia sclerotiorum was most sensitive, with the EC50 being 0.23 microg x mL(-1). As compared with the control, the relative electric conductivity of R. solani treated with Ag-antibiotic 702 was increased by 72.2%, the contents of protein, nucleic acid, and Mg2+ and K+ leaked from the R. solani cells were all increased, while the ergosterol content was decreased by 92.0%. The cell membrane outline was not clear, organelles were badly damaged, and vacuole appeared. It was suggested that the inhibition of ergosterol biosynthesis and the increase of membrane permeability could be the main action mechanisms of Ag-antibiotic 702 against pathogenic fungi.