Endophytic actinomycetes were isolated from Combretum latifolium Blume （Combretaceae）, Western Ghats of Southern India and identified by its characteristic culture morphology and molecular analysis of 16S rRNA gene ...Endophytic actinomycetes were isolated from Combretum latifolium Blume （Combretaceae）, Western Ghats of Southern India and identified by its characteristic culture morphology and molecular analysis of 16S rRNA gene sequences. In this survey of endophytic actinomycetes, a total of 117 isolates representing 9 different genera of endophytie actinomycetes were obtained using four different isolation media and several of them seemed to be novel taxa. Streptomyces genera （35%） was the most frequently isolated strains, followed by Nocordiopsis （17%） and Micromonospora （13%）. ISP-4 medium recovered more isolates （47%） when compared to rest of the media used. Preliminary antibacterial activity of the isolates was carried out by confrontation test. Ethyl acetate fraction of selected isolates in disc diffusion assay exhibited broad spectrum antimicrobial activity against test human pathogens. All Streptomyces spp. strains displayed significant antimicrobial activity against test pathogens. Strain CLA-66 and CLA-68 which are Nocordipsis spp. inhibited both bacterial and fungal pathogens where as other isolates inhibited atleast three test human pathogens in disc diffusion assay. Antimicrobial screening of endophytic actinomycetes from this host may represent a unique potential niche for antimierobial compounds of industrial and pharmaceutical applications. This work is the first comprehensive report on incidence of potential endophytic actinomycetes inhabiting C. latifolium Blnme.展开更多
Drought and salinity are major environmental stresses that impair crop growth and productivity worldwide. Improving drought and salt tolerance of crops with microbial mutualists is an effective and environmentally sou...Drought and salinity are major environmental stresses that impair crop growth and productivity worldwide. Improving drought and salt tolerance of crops with microbial mutualists is an effective and environmentally sound strategy to meet the demands of the ever-growing world population. In the present study, we found that the Streptomyces albidoflavus Osi Lf-2, a moderately salt-tolerant endophytic actinomycete, produced abundant osmolytes, including proline, polysaccharides, and ectoine. Inoculation with Osi Lf-2 increased the osmotic-adjustment ability of the rice host by increasing the proline content(by250.3% and 49.4%) and soluble sugar(by 20.9% and 49.4%) in rice under drought and salt conditions, relative to the uninoculated control. Osi Lf-2 increased stress responses in the rice host at the physiological and biochemical levels(photosynthesis efficiency, osmolytes and antioxidant content), and the gene level(osmolytes synthesis, stress-responsive and ion-transport related genes), raising rice yields under both greenhouse and saline–alkaline soil conditions. The use of endophytic actinomycetes offers a promising biotechnological approach to developing stress-tolerant plants.展开更多
文摘Endophytic actinomycetes were isolated from Combretum latifolium Blume （Combretaceae）, Western Ghats of Southern India and identified by its characteristic culture morphology and molecular analysis of 16S rRNA gene sequences. In this survey of endophytic actinomycetes, a total of 117 isolates representing 9 different genera of endophytie actinomycetes were obtained using four different isolation media and several of them seemed to be novel taxa. Streptomyces genera （35%） was the most frequently isolated strains, followed by Nocordiopsis （17%） and Micromonospora （13%）. ISP-4 medium recovered more isolates （47%） when compared to rest of the media used. Preliminary antibacterial activity of the isolates was carried out by confrontation test. Ethyl acetate fraction of selected isolates in disc diffusion assay exhibited broad spectrum antimicrobial activity against test human pathogens. All Streptomyces spp. strains displayed significant antimicrobial activity against test pathogens. Strain CLA-66 and CLA-68 which are Nocordipsis spp. inhibited both bacterial and fungal pathogens where as other isolates inhibited atleast three test human pathogens in disc diffusion assay. Antimicrobial screening of endophytic actinomycetes from this host may represent a unique potential niche for antimierobial compounds of industrial and pharmaceutical applications. This work is the first comprehensive report on incidence of potential endophytic actinomycetes inhabiting C. latifolium Blnme.
基金financial support from the National Natural Science Foundation of China(31672093 and 31871595)National Key Research and Development Program of China(2018YFD1000603)+1 种基金Hunan Provincial Important Science and Technology Specific Projects(2018NK1010)Key Research and Development Project in Hunan Province,China(2019NK2192)。
文摘Drought and salinity are major environmental stresses that impair crop growth and productivity worldwide. Improving drought and salt tolerance of crops with microbial mutualists is an effective and environmentally sound strategy to meet the demands of the ever-growing world population. In the present study, we found that the Streptomyces albidoflavus Osi Lf-2, a moderately salt-tolerant endophytic actinomycete, produced abundant osmolytes, including proline, polysaccharides, and ectoine. Inoculation with Osi Lf-2 increased the osmotic-adjustment ability of the rice host by increasing the proline content(by250.3% and 49.4%) and soluble sugar(by 20.9% and 49.4%) in rice under drought and salt conditions, relative to the uninoculated control. Osi Lf-2 increased stress responses in the rice host at the physiological and biochemical levels(photosynthesis efficiency, osmolytes and antioxidant content), and the gene level(osmolytes synthesis, stress-responsive and ion-transport related genes), raising rice yields under both greenhouse and saline–alkaline soil conditions. The use of endophytic actinomycetes offers a promising biotechnological approach to developing stress-tolerant plants.
