Isolation, selection of phosphate and potassium solubilising rhizosphere bacteria from coffee cultivated soil of the Central Highlands

Abstract

In this study, 16 phosphate (P) and potassium (K) solubilising bacterial strains were isolated from the rhizosphere of coffee trees cultivated in the Central Highlands. Among them, ‘CF19’ strain was determined to exhibit the highest phosphate solubilisation (145.55 mg/l PO43-). This strain also showed an ability to solubilise two phosphate types, AlPO4 and Fe2(SO4)3. The typical colonies of ‘CF19’ strain were recorded to have circular, concave, sleek and wet surface with white colour. This train has the ability to produce catalase enzyme and siderophore. ‘CF19’ strain showed the highest phosphate solubilisation on the medium with glucose (C resource), (NH4)2SO4 and yeast extract (N resources). This strain could grow in the medium pH 4-5, and salt resistance up to 10%. CF19 could synthesise plant regulator IAA. After 4 days of culture on NBRIP medium containing L-Tryptophan, the maximum amount of IAA approximately reached 68.79 μg/ml. This strain also showed the antagonistic activity against Fusarium oxysporum.