Occurrence, distribution and genetic diversity of soil Phosphate Solubilizing Bacteria in soils of different chemical characteristics in Kenya

Phosphorus (P) availability in many soils is limited by high fixation and precipitation reactions, rendering it inaccessible for plant uptake. The ability to convert insoluble forms of P to an accessible form is an important trait in plant growth-promoting bacteria. The use of phosphate solubilizing bacteria (PSB) as inoculants has potential to increase plant P uptake and yield. Isolation of bacterial strains exhibiting high ability to solubilize insoluble P from soil and rock phosphate is therefore a matter of significant interest with practical applicability. Unfortunately this had never been done in Kenyan soils whereas natural P sources are available locally such as Minjingu phosphate rock from Tanzania. This study focused on the assessment of the native populations of PSB in thirteen Kenyan soils from five agro-ecological zones through their isolation, selection, molecular characterization and identification (sequencing of 16S rRNA gene). The occurrence and diversity of phosphate solubilizing microorganisms was investigated in cultivated land from thirteen sites. Air dried soil samples were serially diluted and plated in the National Botanical Research in Phosphate media (NBRIP). The results showed higher diversity of phosphate solubilizing fungi than PSB in low (Central, Nyanza, Trans Nzoia and Kisii) and high pH soils (Coast). The soils with a high PSB population had a near neutral soil pH (pH 5.8-6.8). Restriction fragment length polymorphism analysis revealed that the strains belonged to atleast 20 interspacer group (IGS) profiles. IGS profile II had the highest dominance among all the soils accounting for 56% dominance, and belonged mainly to Bacillus megaterium. There were 130 isolates which have been identified to genus and species level. The isolated microorganisms with phosphate solubilizing ability were either Bacillus sp., B. megaterium, Bacillus amyloliquefaciens, Paenibacillus sp. or Arthrobacter sp. Further studies on the assessment of the P solubilizing capacities of such PSB and on the interaction of the effective strains with crops are ongoing and should give us some relevant results on the potential of PSB to improve cereal and legume yields in Kenya. (Texte intégral)

Bibliographic Details

Main Authors:	Ndung'u, Keziah, Herrmann, Laetitia, Okalebo, John Robert, Othieno, Calebo O., Pypers, Pieter, Lesueur, Didier
Format:	conference_item biblioteca
Language:	eng
Published:	s.n.
Subjects:	P34 - Biologie du sol, F04 - Fertilisation,
Online Access:	http://agritrop.cirad.fr/558117/ http://agritrop.cirad.fr/558117/1/document_558117.pdf
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