ISOLATION AND CHARACTERIZATION OF PHOSPHATE SOLUBILIZING BACTERIA COMPRISING PGPR TRAITS FROM CULTIVATED AS WELL AS NON-CULTIVATED SOIL
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Date
2012
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AAU, Anand
Abstract
Series of experiments were carried out to investigate P solubilization and plant growth promoting abilities of native PSB isolates obtained from cultivated as well as non-cultivated soils of Anand and Panchmahal-Vadodara hilly mining regions. Out of 115 suspected bacterial cultures isolated by modified Sperber's technique, 14 were found efficient for in vitro P solubilization and from which four prominent isolates were selected for further studies based on their efficiency to solubilize P substrates, tri calcium phosphate (TCP) and rock phosphate (RP). Isolate P 19 was most efficient for TCP and RP solubilization, making available 954.76 and 283.03 µg/ml free P. HPLC analysis revealed that P 19 was producing maximum 35,708.78 µg/ml total organic acid amongst four isolates in liquid medium. PSB isolates were characterized through morphological, biochemical as well as molecular methods. 16S rDNA sequencing analysis designated native isolates, A 37 as Burkholdeha sp., A 39 as Pseudomonas aeruginosa, P 19 as Burkholderia cepacia and P 23 as Bacillus circulans. They were able to tolerate wide range of pH, NaCl concentrations and antibiotics. Additionally, Burkholderia sp. (A 37 & P 19) were found positive for nifH gene with production of IAA up to 58.34 µg/ml. All the four isolates were found positive for PGPR traits like ACC deaminase production, insoluble potash solubilization, siderophore production as well as lytic enzyme production with growth inhibition of plant pathogenic fungi. Among the tested isolates B. cepacia P 19 inhibited 44 % growth of Macrophomina phaseolina. PSB isolates showed significant growth enhancement of soybean in laboratory and pot conditions. In pots, seed + soil and seed + soil + foliar applications of B. cepacia P 19 showed significant growth enhancement over untreated control with 25 % reduction in chemical P fertilizer.
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AGRICULTURAL MICROBIOLOGY, CHARACTERIZATION