Functional characterization and molecular fingerprinting of potential phosphate solubilizing bacterial candidates from Shisham rhizosphere

Abstract

Phosphate solubilizing bacteria (PSB) are important role players in plant growth promotion. In the present study, we aimed to screen the functionally active phosphate solubilizing bacteria (PSB) associated with Dalbergia sissoo Roxb. (Shisham) from different provenances. Screening for phosphate solubilization was done on Pikovskaya's agar, and 18 bacteria positive for the tri-calcium phosphate (Ca3(PO4)2 solubilization showing visible dissolution halo zones were identified. All 18 isolates showed zinc solubilization, indole acetic acid (IAA), siderophore, and hydrogen cyanide (HCN) production. The morphological and biochemical characterization with 16S rDNA gene-based phylogenetic analysis identified bacterial strains as belonging to the genus Pseudomonas, Klebsiella, Streptomyces, Pantoea, Kitasatospora, Micrococcus, and Staphylococcus. Among all the isolates, one of the isolates named L4, from Lacchiwala region was the most efficient P solubilizer with a high P solubilization index (4.75 ± 0.06) and quantitative P solubilization activity (891.38 ± 18.55 μg mL−1). The validation of phosphate solubilization activity of PSB isolates was done by amplification of the Pyrroloquinoline quinone (PQQ) genes, pqqA and pqqC. Based on this study, we have selected the bacterial strains which are efficient phosphate solubilizers and could be economical and eco-friendly in plant growth promotion, disease suppression, as an antioxidant, and for subsequent enhancement of yield.

Pseudomonas taetrolens ULE-PH5 and Pseudomonas sp. ULE-PH6 Isolated from the Hop Rhizosphere Increase Phosphate Assimilation by the Plant

“…The characterization of the 5 best phosphate solubilizers in solid NBRIP medium indicated that 4 of them (isolates ULE-PH1, ULE-PH5, ULE-PH6, and ULE-PH12) belonged to the Pseudomonas genus, whereas 1 belonged to the Bacillus genus (isolate ULE-PH10). Pseudomonas species were also the most frequently isolated PSBs from the rhizosphere of barley plants (9 out of the 17; 52.94%) [21], and the rhizosphere of shisham plants (7 out of 18 isolates; 38.89%) [49]. They were also dominant [50].…”

Microbial composition and diversity of the tobacco leaf phyllosphere during plant development

“…Enterobacter favorably maintained an advantage on the tobacco phyllosphere during the squaring development, and thus mediated significantly different metabolic functions, like carrying out the process of 3-phenylpropanoate and 3-(3-hydroxyphenyl) propanoate degradation, cinnamate and 3-hydroxycinnamate degradation to 2-oxopent-4-enoate, and aerobactin biosynthesis ( Supplementary Table S2 ). Similarly, studies have showed that some of Enterobacter species are capable to solubilize phosphate and/or potassium necessary for plant growth and development ( Joshi et al, 2023 ). They produce plant-growth regulators or establish quorum sensing systems on leaves, which enable them to hold in check pathogens on leaves ( Przemieniecki et al, 2019 ).…”

Soil phosphorus transformation and plant uptake driven by phosphate-solubilizing microorganisms

“…Gluconic acid is synthesized by the oxidation of glucose by GDH, which requires pyroquinoline quinone (PQQ) as a cofactor to participate in the reaction ( Karagoz et al, 2020 ; Wu et al, 2022 ). PQQ synthesis involves six core genes ( pqqA , pqqB , pqqC , pqqD , pqqE , and pqqF ) associated with dehydrogenase activity and mineral phosphate dissolution in microorganisms ( Wan et al, 2020 ; Dudeja et al, 2021 ; Joshi et al, 2023 ). The pqqA gene plays an important role in PQQ biosynthesis and P solubilization.…”