Plant Growth-Promoting Endophyte Serratia marcescens AL2-16 Enhances the Growth of Achyranthes aspera L., a Medicinal Plant

An endophytic bacterium, AL2-16, was isolated from Achyranthes aspera L. It was characterized and identified as Serratia sp. AL2-16 and was experimented for the presence of plant growth-promoting properties. AL2-16 produced siderophore in iron-deficient conditions. The quantitative estimation of siderophore production unit of AL2-16 was maximum after 48 hours of incubation (83.488%) in the presence of 1 μM of ferric chloride. The fructose followed by glucose and sucrose were proved to be the best carbon sources resulting in appreciable amount of siderophore production, i.e. 77.223%, 73.584%, and 65.363% respectively. AL2-16 also has the ability to produce indole acetic acid in medium supplemented with l-tryptophan. The highest amount of indole acetic acid, in the presence of 1.0% l-tryptophan, was 123.2 μg/mL after 144 hours. This isolate solubilized inorganic phosphate and also gave positive result for ammonia production. Colonization and pot trial experiments were conducted on A. aspera L. plant. The population of AL2-16 increased from 16.2 × 106 to 11.2 × 108 colony forming unit/g between 3rd and 5th days after inoculation. It significantly (p ≤ 0.05) increased shoot length by 95.52%, fresh shoot weight by 602.38%, fresh root weight by 438%, and area of leaves by 127.2% when inoculated with AL2-16, as compared with uninoculated control

Plant Growth-Promoting Endophyte Serratia marcescens AL2-16 Enhances the Growth of Achyranthes aspera L., a Medicinal Plant

An endophytic bacterium, AL2-16, was isolated from Achyranthes aspera L. It was characterized and identified as Serratia sp. AL2-16 and was experimented for the presence of plant growth-promoting properties. AL2-16 produced siderophore in iron-deficient conditions. The quantitative estimation of siderophore production unit of AL2-16 was maximum after 48 hours of incubation (83.488%) in the presence of 1 μM of ferric chloride. The fructose followed by glucose and sucrose were proved to be the best carbon sources resulting in appreciable amount of siderophore production, i.e. 77.223%, 73.584%, and 65.363% respectively. AL2-16 also has the ability to produce indole acetic acid in medium supplemented with l-tryptophan. The highest amount of indole acetic acid, in the presence of 1.0% l-tryptophan, was 123.2 μg/mL after 144 hours. This isolate solubilized inorganic phosphate and also gave positive result for ammonia production. Colonization and pot trial experiments were conducted on A. aspera L. plant. The population of AL2-16 increased from 16.2 × 106 to 11.2 × 108 colony forming unit/g between 3rd and 5th days after inoculation. It significantly (p ≤ 0.05) increased shoot length by 95.52%, fresh shoot weight by 602.38%, fresh root weight by 438%, and area of leaves by 127.2% when inoculated with AL2-16, as compared with uninoculated control

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

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

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