Isolation of phosphate solubilizingPseudomonasstrains from apple rhizosphere in the Trans Himalayan region of Himachal Pradesh, India

Abstract

Total fifteen phosphate solubilizing bacteria were isolated from rhizosphere soil of apple tree on Kings' B medium belonging to genus Pseudomonas spp. They were characterized on the basis of morphological and biochemical characteristics. Preliminary selection as phosphate solubilizing bacteria were done on the basis of formation of transparent zone around the colony on Pikovskaya's agar medium containing 0.5% triclcium phosphate (TCP).Maximum in vitro phosphate solubilization on Pikovskaya's agar plates after 72h incubation at 28 0 C was shown by An-15-Mg (46 mm), whereas in case of broth, again this strain showed maximum tricalcium phosphate (TCP) solubilization (76 µg/ml). The pH of each inoculated broth was recorded daily and dropped significantly (pH 7.0-3.99). All the Pseudomonas isolates were further evaluated for overall plant growth promoting traits. Greatest siderophore activity was exhibited by An-14-Mg (71.23 %SU) followed by An-15-Mg (70.12 %SU) which were statiscally at par with each other. Whereas, maximum IAA production was observed again in An-15-Mg (95 µg/ml).This isolate also showed the maximum production of HCN and ammonia. 16S rDNA and phylogenetic analysis showed that strain An-15-Mg exhibits 99% level of similarity with Pseudomonas aeruginosa. Therefore, it was designated as Pseudomonas aeruginosa strain An-15-Mg. HPLC analysis showed that the Pseudomonas aeruginosa strain An-15-Mg produced maximum concentration of succinic acid, malonic, citric and malic acid with small amounts of schimic, quinic, tartaric, fumaric and lactic acids. The strain An-15-Mg possessed phosphate solubilization as major PGP trait along with different PGP traits. The potential phosphate solubilizing strain of Pseudomonas aeruginosa was reported first time as PGPR which lives in close association with apple tree without harming the plant, therefore could be used as a promising phosphate solubilizer and biofertilizer in apple crop grown in high hills of Himachal Pradesh.

The influence of biofertilization on the vegetative growth, yielding and nutritional status of 'Sampion' apple trees in first years after planting

“…Phosphorus and potassium fertilizers are not effectively used at low soil pH. Sharma et al (2017) studied the bacteria of the genus Pseudomonas inhabiting the roots of apple trees in terms of their ability to dissolve insoluble phosphorus compounds. They believe that organic compounds secreted by apple roots can stimulate the multiplication of phosphorolytic (fluorescing) Pseudomonas bacteria and Bacillus bacteria.…”

Metagenomic Analysis of Bacterial Communities in Agricultural Soils from Vietnam with Special Attention to Phosphate Solubilizing Bacteria

“…In addition, numerous PSB bacteria were previously identified as members of genus Pseudomonas with plant growth promoting ability. For instance, the phosphate solubilizing ability of a P. aeruginosa strain was reported by Sharma et al, and was reckoned as a potential phosphate solubilizer and biofertilizer in apple crops [ 76 ]. Additionally, endophytic PSB Pseudomonas fluorescens isolates were shown to stimulate the growth of Pisum sativum L. plants [ 77 ].…”

Characterization and Field Evaluation of Potential Fluorescent Pseudomonas Isolates on Growth and Yield Attributing Characters in Chickpea

“…Paul and Sinha (2017) found that Pseudomonas strain KUPSB12 demonstrated an effective phosphate solubilization index of 2.85 on Pikovskya agar plates, along with a very high production of soluble phosphate (219±0.33 µg ml -1 ) in a liquid medium. Similarly, Sharma et al (2017) reported that potential phosphate solubilizing Pseudomonas aeruginosa strain An-Mg, isolated from the rhizosphere soil of apple trees, could serve as both a biofertilizer and a potential biocontrol agent. Kloepper et al (1988) highlighted phosphorus solubilization as the most readily available form for plant growth.…”