Phosphate Solubilization Index Research Articles

Induced Inorganic Phosphate Solubilization Through N-Methyl-N´-Nitro-N-Nitrosoguanidine Treated Mutants of Pseudomonas koreensis Strain AK-1 (MTCC Number 12058) Under Polyethylene Glycol

In the present study, a wild type and mutant strain of Pseudomonas koreensis strain AK-1 (MTCC number 12058) was used for enhanced inorganic phosphorus solubilization under drought stress. Five mutants namely AK-1a, AK-1b, AK-1c, AK-1d and AK-1e were found to solubilize inorganic phosphates more than that of wild type strain in drought stress of 0–10 % polyethylene glycol. On the basis of solubilization index on Pikovskaya agar medium the highest phosphate solubilization index was recorded by mutant strain AK-1c as compared to the wild type strain (AK-1). AK-1c gave the highest Phosphate solubilization index (7.67) at 0 % of polyethylene glycol concentration and lowest (3.6) at the 10 % of polyethylene glycol. AK-1e showed the lowest (4.85) at 0 % and 2.6 at 10 % P solubilization index among the five mutant strains while AK-1 wild type strain showed 4.12 at 0 % and 2.33 at 10 % polyethylene glycol. A highest (19.82) μg/ml at 2 % and 9.73 μg/ml at 10 % PEG inorganic phosphate was solubilized by AK-1c mutant strain which was more than that of wild type variety (17 μg/ml at 2 % and 7.5 μg/ml at 10 % PEG). In plant growth promoting experiment, mutant (AK-1c and AK-1a) bacterial treated soybean plants showed increased shoot length, root length, shoot fresh weight, root fresh weight and number of lateral roots under drought stress as compared to untreated control plants. Bacteria treated soybean plants in Murashige Scoog media showed significant increase in number of lateral roots as compared to the control.

Characterization of phosphate solubilizing bacteria isolated from Pb contaminated soils and their potential for dissolving tricalcium phosphate

Phosphorus solubilizing bacteria (PSB) enhances P availability in soils through dissolving inorganic P pools. The characteristics of PSB and the potential of three Pb tolerant phosphate solubilizing rhizobacteria, i.e. Pseudomonassp, Bacillus sp., and Actinomycites sp. were evaluated. PSB were isolated from soil samples contaminated with 300 and 500 mg Pb/kg after incubation for 30 days. Phosphate solubilizing bacteria were screened on for phosphate solubilisation ability in Pikovskaya agar medium (PA). In addition, two of the three indentified PSB strains (Pseudomonas sp. and Bacillus sp.) were characterized for their ability to solubilize tricalcium phosphate in Pikoskaya broth (PB) and also were examined their growth during culture medium incubation. The isolates exhibited different phosphate solubilization index, ranging from 1.87 to 2.98. Pseudomonas sp. had the highest ability to solubilize tricalcium phosphate: 9.82 mg P/ L and 12.23 mg P/ Lin Pikoskaya broth following the addition of 4 mg Pb/L and 2 mg /Pb L, respectively.Â

Solubilization of inorganic phosphate and production of organic acids by bacteria isolated from a Moroccan mineral phosphate deposit

Three efficient inorganic-phosphate solubilizing bacteria (PSB) were isolated from a phosphate rock deposit of a Moroccan mine. The phosphate solubilization index of these isolates, determined in National Botanical Research Institute's phosphate (NBRIP) medium supplemented with tribasic calcium phosphate, ranging from 2.8 to 4.4. The medium pH dropped from 7.0 to 3.5 units after growth under continuous agitation for seven days. PSB6, the most efficient PSB, closely related to

Biochemical and Molecular Characterization of High Population Density Bacteria Isolated from Sunflower

Natural and beneficial associations between plants and bacteria have demonstrated potential commercial application for several agricultural crops. The sunflower has acquired increasing importance in Brazilian agribusiness owing to its agronomic characteristics such as the tolerance to edaphoclimatic variations, resistance to pests and diseases, and adaptation to the implements commonly used for maize and soybean, as well as the versatility of the products and by-products obtained from its cultivation. A study of the cultivable bacteria associated with two sunflower cultivars, using classical microbiological methods, successfully obtained isolates from different plant tissues (roots, stems, florets, and rhizosphere). Out of 57 plantgrowth- promoting isolates obtained, 45 were identified at the genus level and phylogenetically positioned based on 16S rRNA gene sequencing: 42 Bacillus (B. subtilis, B. cereus, B. thuringiensis, B. pumilus, B. megaterium, and Bacillus sp.) and 3 Methylobacterium komagatae. Random amplified polymorphic DNA (RAPD) analysis showed a broad diversity among the Bacillus isolates, which clustered into 2 groups with 75% similarity and 13 subgroups with 85% similarity, suggesting that the genetic distance correlated with the source of isolation. The isolates were also analyzed for certain growth-promoting activities. Auxin synthesis was widely distributed among the isolates, with values ranging from 93.34 to 1653.37 microM auxin per microng of protein. The phosphate solubilization index ranged from 1.25 to 3.89, and siderophore index varied from 1.15 to 5.25. From a total of 57 isolates, 3 showed an ability to biologically fix atmospheric nitrogen, and 7 showed antagonism against the pathogen Sclerotinia sclerotiorum. The results of biochemical characterization allowed identification of potential candidates for the development of biofertilizers targeted to the sunflower crop.