Genetic diversity of phosphate-solubilizing peanut (Arachis hypogaea L.) associated bacteria and mechanisms involved in this ability

Abstract

In this study, attempts were made to analyze mechanisms involved in the bacterial phosphate-solubilizing ability of peanut isolates. Bacteria were taxonomically identified by analysis of 16S rDNA sequence. Levels of soluble P released by the isolates in unbuffered or buffered with Tris-HCl or MES NBRIP-BPB medium as well as the production of Dgluconic acid were determined in their culture. Presence of two of the genes encoding the cofactor PQQ of GDH enzyme was analyzed in the genome of this bacterial collection. 16S rDNA sequence analysis indicated that isolates belong to genera Serratia, Enterobacter, Pantoea, Acinetobacter, Bacillus and Enterococcus. All bacteria showed ability to solubilize tricalcium phosphate either in unbuffered or buffered medium. Nevertheless, addition of buffer solutions reduced levels of Pi liberated by the isolates. Although almost all isolates produced detectable amounts of D-gluconic acid, no correlation with levels of P soluble released were observed. The presence of pqqE and pqqC genes was detected only in Gram negative bacteria. It was concluded from this study that the mechanism involved in phosphate solubilization is organic acids production and, presence of pqq genes in all Gram negative bacteria analyzed encourages to confirm their role in bacterial phosphate solubilizing ability as well to identify genes involved in this PGP trait in Gram positive bacteria.

Inoculation of pqq E gene inhabiting Pantoea and Pseudomonas strains improves the growth and grain yield of wheat with a reduced amount of chemical fertilizer

“…in current study. Our results are in line with the previous studies which reported that these organic acids play a vital role in lowering the pH of the growth medium and solubilization of phosphates (Malboobi et al 2009;Andreeva et al 2011;Castagno et al 2011;Anzuay et al 2013;Tahir et al 2013). Both these strains lowered the pH of the medium and solubilized maximum amount of P (311 AE 4 by Pantoea WP-5 and 298 AE 5 by Pseudomonas NN-4) on glucose-supplemented medium.…”

“…This may be due to the reason that in DataBank (NCBI) the nucleotide sequences of pqqE gene are only available for Pseudomonas and Bacillus in BLAST search and the tested strains might have acquired this gene through horizontal gene transfer at some point of their phylogenetic history. The amplification and sequencing of pqqE gene in the phosphate-solubilizing strains of Pantoea and Pseudomonas has been reported previously (Andreeva et al 2011;Anzuay et al 2013;Kremmydas et al 2013). Our results confirmed the indirect role of pqqE gene in inorganic phosphate solubilization and this has been reported in previous studies (Ben Farhat et al 2009;Holscher et al 2009).…”

Plant growth‐promoting effects of native Pseudomonas strains on Mentha piperita (peppermint): an in vitro study

“…Direct promotion of plant growth occurs through providing the plant with a useful compound synthesised by the bacteria, or facilitating plant uptake of specific nutrients from the environment. Pseudomonas species produce siderophores (Mavrodi et al 2001) and participate in phosphate solubilisation (Anzuay et al 2013), thereby making soil iron and phosphorus accessible to the plant. Fluorescent pseudomonads also produce the phytohormone indole-3-acetic acid (IAA; Patten & Glick 2002) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which sequesters the ethylene precursor (Van Loon 2007).…”

Isolation and Characterization of Endophytic Bacteria Associated with Roots of Jojoba (<i>Simmondsia chinensis</i> (Link) Schneid)

“…The isolated Bacillus sp. (JRP 39) showed the highest phosphorus solubilization capacity compared to the other strains tested (Table 3), as it is known that this genus can solubilize tricalcium phosphate 19 . Our results suggest the possibility of using this bacterium as a plant growth promoter in arid and semiarid regions, as it increases the availability of inorganic phosphorus in the soil.…”