Streptomyces manipurensis MBRL 201T as potential candidate for biocontrol and plant growth promoting agent for rice

741-749Globally, there is a need to enhance agricultural productivity safely to feed the growing human population without massive use of chemical pesticides and fertilizers, as it causes adverse effects on environment. Biocontrol activities and use of plant growth promoting (PGP) bacteria holds great promise for an ecofriendly sustainable organic agriculture. In this context, here, we studied a novel species, Streptomyces manipurensis MBRL 201T for its biocontrol and growth promoting potential in rice. It was found to exhibit antagonistic activity against 6 important rice fungal pathogens by diffusible and volatile compounds production. The culture filtrates also exhibited significant inhibition. The strain was positive for PKS-II and NRPS genes. The strain produced fungal cell wall degrading enzymes, such as chitinase, β-1,4-glucanase, lipase and protease, and volatile compound, such as ammonia. The strain could produce 50.05 µg mL-1 of IAA, highest siderophore in starch casein nitrate broth (88.05%) and solubilize 76 µg mL-1 of phosphate. The strain was also positive for ACC deaminase activity. Highest vigor index was observed when rice seeds were treated with 6×107cfu mL-1 of MBRL 201T. The strain could enhance seeds germination and growth of rice seedlings even under pathogen challenged conditions. Treatment of the strain through seeds dipping and foliar spray exhibited significant effects on growth of rice under greenhouse and field conditions. The strain has the potential to be used as biocontrol and/ biofertilizing agents for application in rice plant

Acidotolerant Streptomyces sp. MBRL 10 from limestone quarry site showing antagonism against fungal pathogens and growth promotion in rice plants

Acidotolerant Streptomyces sp. MBRL 10 isolated from limestone deposit site on Gauze’s medium No. 1 (pH 5.3) showed significant antagonism against the tested fungal pathogens. It exhibited the highest mycelial growth inhibition by diffusible and volatile compound(s) production against Rhizoctonia solani. Culture filtrates also exhibited significant inhibition zone but the inhibition activities vanished when sterilized. The strain produced chitinase, β-1,3-glucanase, lipase, protease and ammonia but not β-1,4-glucanase. It could produce 25 μg/ml of indole acetic acid, solubilize up to 140 μg/ml of phosphate with a concomitant decrease in pH of the medium. The bioactive actinomycete strain produced hydroxamate type of siderophore. Casamino acid was found to be the best medium for siderophore production (87% siderophore units).MBRL 10 showed the highest rice seedlings vigor index corresponding to an inoculum size of 0.3 × 108 cfu/ml. Strain treated rice seeds at an inoculum size of 0.3 × 108 cfu/ml showed higher germination percentage and significantly enhanced (P ⩽ 0.05) the growth of seedlings. Strain treated rice seedlings challenged with pathogens also exhibited higher germination percentages and significantly enhanced (P ⩽ 0.05) growth over seedlings challenged with pathogen alone in the absence of the bioinoculant. Rice plants treated with the strain significantly promote (P ⩽ 0.05) the growth under nethouse conditions. Keywords: Streptomyces sp. MBRL 10, Acidotolerant, Antagonism, Plant growth promoting traits, Vigor index, Rice plant

Biocontrol and plant growth promoting activities of a Streptomyces corchorusii strain UCR3-16 and preparation of powder formulation for application as biofertilizer agents for rice plant

Streptomyces corchorusii strain UCR3-16, obtained from rice rhizospheric soils showed antifungal activities against 6 major rice fungal pathogens by diffusible and volatile compounds production. The strain was found positive for production of fungal cell wall degrading enzymes such as chitinase, beta-1,3-glucanase, beta-1,4-glucanase, lipase and protease. The strain was also positive for plant growth promoting traits. It produced up to 30.5 mu g/ml of IAA and solubilized a significant amount of inorganic phosphate (up to 102 mu g/ml). It also produced 69% siderophore units. The strain also produced ammonia and gave positive result for ACC deaminase activity. Highest vigor index of inoculated seedlings was observed when rice seeds were treated with cell suspension of UCR3-16 corresponding to 4.5 x 10(8) cfu/ml. Bioinoculant-treated seeds also showed similar results under pathogen challenged conditions. In pot trial experiments, UCR3-16-treated rice plants showed significantly increased growth and grain yield production. Powder formulation of the strain was developed using talcum and corn starch as carriers and the shelf-lives were monitored. Talcum formulation showed higher cell-count than corn starch even after 6 months of storage, and optimum condition for storage of the powder formulation were found to be at 4 degrees C. Pot trial experiments using talcum powder formulation also showed significant positive effects on growth of rice plants. Field trial using talcum powder formulation also exhibited significant enhancement in shoot length and weight of shoot and root, and total grain yield and weight of grains in rice plants. Talcum formulation also significantly reduced the sheath blight disease in rice leaves. (C) 2016 Published by Elsevier GmbH

Acidotolerant Streptomyces sp. MBRL 10 from limestone quarry site showing antagonism against fungal pathogens and growth promotion in rice plants

AbstractAcidotolerant Streptomyces sp. MBRL 10 isolated from limestone deposit site on Gauze’s medium No. 1 (pH 5.3) showed significant antagonism against the tested fungal pathogens. It exhibited the highest mycelial growth inhibition by diffusible and volatile compound(s) production against Rhizoctonia solani. Culture filtrates also exhibited significant inhibition zone but the inhibition activities vanished when sterilized. The strain produced chitinase, β-1,3-glucanase, lipase, protease and ammonia but not β-1,4-glucanase. It could produce 25μg/ml of indole acetic acid, solubilize up to 140μg/ml of phosphate with a concomitant decrease in pH of the medium. The bioactive actinomycete strain produced hydroxamate type of siderophore. Casamino acid was found to be the best medium for siderophore production (87% siderophore units).MBRL 10 showed the highest rice seedlings vigor index corresponding to an inoculum size of 0.3×108cfu/ml. Strain treated rice seeds at an inoculum size of 0.3×108cfu/ml showed higher germination percentage and significantly enhanced (P⩽0.05) the growth of seedlings. Strain treated rice seedlings challenged with pathogens also exhibited higher germination percentages and significantly enhanced (P⩽0.05) growth over seedlings challenged with pathogen alone in the absence of the bioinoculant. Rice plants treated with the strain significantly promote (P⩽0.05) the growth under nethouse conditions