Journal des sciences agricoles et de la recherche alimentaire
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Abstrait

Isolation, Screening and Biochemical Characterization of Phosphate- Solubilizing Rhizobacteria Associated with Coffea arabica L.

Befekadu Teshome, Misganaw Wassie and Endeshaw Abatneh

This study focused on screening, identifying and characterizing P-solubilizing rhizobacteria associated with Coffea arabica L. growing in Southwestern Ethiopia. Samples were collected from Kaffa and Jimma zones in the Southwestern part of Ethiopia which are not only the major coffee growing areas of Ethiopia but also the origin of Coffea arabica L. Natural forest, agroforestry-based and monoculture plantations were included. A total of 110 Coffee roots with adhering soil samples were collected in sterile plastic bags. At each sampling site, plant roots with adhering soil (approximately 50 g) were collected from each corner of a randomly selected square meter (One from each of 4 quadrants) which lied around coffee plant at a depth of 10-20 cm and placed into a sterile plastic bag to give a composite sample. One composite sample was taken at each coffee plant. Care was taken to keep rhizosphere soil intact around the root. The shade trees at each sampling site were also registered. A total of 169 bacteria were isolated on nutrient agar from root washing solutions (61 isolates), surface sterilized roots (45 isolates) and soil (63 isolates). These bacteria isolates were subjected to GEN III Micro-plate tests of Biolog bacterial identification system kits and evaluated for their ability to solubilize phosphates on Pikovskaya’s agar plates. Members of the isolated rhizobacteria were dominated by the genus Pseudomonas (44.1%) followed by Bacillus (11.6%), Enterobacter (10.5%) and Stenotrophomonas (10.5%). Over 32.5% of the Rhizobacteria (both Gram-negative and Gram-positive) associated with the coffee rhizosphere could solubilize mineral P on Pikovskaya’s agar, indicating a high proportion of such species is associated with coffee plants.