Occurrence and genetic diversity of phosphate-solubilizing bacteria in soils of differing chemical characteristics in Kenya

Ndung'u-Magiroi Keziah Wairimu, Herrmann Laetitia, Okalebo John Robert, Othieno Calebo O., Pypers Pieter, Lesueur Didier. 2012. Occurrence and genetic diversity of phosphate-solubilizing bacteria in soils of differing chemical characteristics in Kenya. Annals of Microbiology, 62 (3) : 897-904.

https://doi.org/10.1007/s13213-011-0326-2

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Quartile : Q3, Sujet : BIOTECHNOLOGY & APPLIED MICROBIOLOGY / Quartile : Q3, Sujet : MICROBIOLOGY

Résumé : This study focused on the isolation, identification (sequencing of 16S rDNA gene) and determination of the phosphorus (P)-solubilizing efficiency of native populations of phosphate-solubilizing bacteria (PSB) in 13 Kenyan soils with differing chemical characteristics. Air-dried soil samples were serially diluted and plated on NBRIP media and enumerated. Their phosphate-solubilizing efficiency was assessed on Frioni's agar. Pearson correlation coefficients were determined between PSB populations and soil properties. The PSB populations varied among the sites tested and had a positive and significant correlation (p ≤ 0.05) with organic carbon (r = 0.76), exchangeable calcium (r = 0.93) and exchangeable magnesium (r = 0.92). A total of 150 isolates were identified to the genus and species level. Among the isolates, Bacillus megaterium, Bacillus sp. and Arthrobacter sp. were the most abundant and well-distributed strains. However, only 5% of the total isolates were efficient in terms of phosphate-solubilizing efficiency. The results indicate that although there were many PSB strains in the soils tested, only a few (5%) were effective in terms of their phosphate-solubilizing ability. It is therefore unlikely that native PSB contribute significantly to solubilizing phosphate in the soils tested, which would ultimately benefit plant growth. Therefore, inoculation with effective strains with a high P solubilization potential is necessary.

Mots-clés Agrovoc : Bacteria, micro-organisme du sol, phosphate, solubilisation, efficacité, composition chimique, propriété physicochimique du sol, variation génétique, génétique des populations, identification, isolement, technique analytique