Gibberellin production and phosphate solubilization by newly isolated strain of Acinetobacter calcoaceticus and its effect on plant growth.
ABSTRACT Plant growth-promoting rhizobacteria with gibberellins (GA)-producing potential were isolated from soil and screened for plant growth promotion. A new strain, Acinetobacter calcoaceticus SE370, produced extracellular GA and also had phosphate solubilising potential. It produced 10 different gibberellins, including the bioactive GA(1), GA(3) and GA(4) which were at, respectively, 0.45, 6.2 and 2.8 ng/100 ml. The isolate solubilised tricalcium phosphate and lowered pH of the medium during the process. Culture filtrates of the organism after growth on broth promoted growth of cucumber, Chinese cabbage and crown daisy.
Article: Isolation, characterization, and use for plant growth promotion under salt stress, of ACC deaminase-producing halotolerant bacteria derived from coastal soil.[show abstract] [hide abstract]
ABSTRACT: In total, 140 halotolerant bacterial strains were isolated from both the soil of barren fields and the rhizosphere of six naturally growing halophytic plants in the vicinity of the Yellow Sea, near the city of Incheon in the Republic of Korea. All of these strains were characterized for multiple plant growth promoting traits, such as the production of indole acetic acid (IAA), nitrogen fixation, phosphorus (P) and zinc (Zn) solubilization, thiosulfate (S2O3) oxidation, the production of ammonia (NH3), and the production of extracellular hydrolytic enzymes such as protease, chitinase, pectinase, cellulase, and lipase under in vitro conditions. From the original 140 strains tested, on the basis of the latter tests for plant growth promotional activity, 36 were selected for further examination. These 36 halotolerant bacterial strains were then tested for 1- aminocyclopropane-1-carboxylic acid (ACC) deaminase activity. Twenty-five of these were found to be positive, and to be exhibiting significantly varying levels of activity. 16S rRNA gene sequencing analyses of the 36 halotolerant strains showed that they belong to 10 different bacterial genera: Bacillus, Brevibacterium, Planococcus, Zhihengliuella, Halomonas, Exiguobacterium, Oceanimonas, Corynebacterium, Arthrobacter, and Micrococcus. Inoculation of the 14 halotolerant bacterial strains to ameliorate salt stress (150 mM NaCl) in canola plants produced an increase in root length of between 5.2% and 47.8%, and dry weight of between 16.2% and 43%, in comparison with the uninoculated positive controls. In particular, three of the bacteria, Brevibacterium epidermidis RS15, Micrococcus yunnanensis RS222, and Bacillus aryabhattai RS341, all showed more than 40% increase in root elongation and dry weight when compared with uninoculated saltstressed canola seedlings. These results indicate that certain halotolerant bacteria, isolated from coastal soils, have a real potential to enhance plant growth under saline stress, through the reduction of ethylene production via ACC deaminase activity.Journal of Microbiology and Biotechnology 11/2010; 20(11):1577-84. · 1.38 Impact Factor
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ABSTRACT: a b s t r a c t Plant growth promoting rhizobacteria (PGPR) has been a focus of research for its potential as an eco-friendly alternative to chemical fertilizers in the agriculture industry. In current study, the effect of culture suspension (CS) of a novel gibberellins (GAs) producing bacterial strain Burkholderia sp. KCTC 11096BP, was observed on shoot length, shoot fresh and dry biomass, root fresh and dry biomass, chlorophyll contents, endogenous bioactive GAs (GA 1 and GA 4) and their immediate precursors, abscisic acid (ABA), soluble sugar contents and crude protein contents of cucumber (Cucumis sativus L.). We found that growth attributes of cucumber were significantly promoted by the application of CS of Burkholderia sp. KCTC 11096BP. The quantity of GA 1 and GA 4 and their immediate precursors GA 20 and GA 9 respec-tively, were also significantly promoted as compared to their respective controls. Contrary to GAs, the quantity of endogenous free ABA in cucumber leaves was much lower in bacterial CS treated plants. Soluble sugar contents and crude protein contents of cucumber leaves were also significantly higher in bacterial CS treatments as compared to control. It was concluded that Burkholderia sp. KCTC 11096BP can be used as an eco-friendly bio-fertilizer in our farming systems.Scientia Horticulturae 04/2010; · 1.53 Impact Factor