Isolation and Identification of Phosphorussolubilizing Bacteria from Soil Andtomatorhizosphere in Iree Town, Osun State.

ABSTRACT
Phosphorus (P) is a critical macronutrient essential for plant growth, playing key roles
in energy transfer, root development, and photosynthesis. However, despite its
abundance, phosphorus often exists in insoluble forms in soil, making it unavailable
to plants. This study aimed to assess the physicochemical and microbiological
properties of phosphorus-solubilizing bacteria (PSB) in soil and the tomato
rhizosphere in Iree, Osun State, Nigeria. Soil samples were collected from Campus,
Eyinade and Baptist area before and after planting to evaluate pH, temperature, and
bacterial counts. Initial pH values ranged from 8.2 to 8.8, while post-planting samples
showed a slight decrease to a range of 8.4 to 8.6, likely due to acid production by PSB.
Bacterial counts decreased after planting, with the highest count observed at 4.3 x 10⁶
CFU/g in campus soil before planting, which dropped to 1.8 x 10⁶ CFU/g post
planting. The PSB isolates were identified and characterized based on colonial,
morphological, and biochemical features, with predominant bacteria including
Bacillus spp., Pseudomonas putida, Enterococcus spp., and Alcaligenes spp., known
for their phosphorus-solubilizing abilities. Bacillus spp. and Pseudomonas putida
showed significant potential for improving phosphorus bioavailability, supporting
existing research on their role in sustainable agriculture. This study highlights the
effectiveness of using PSB as biofertilizers, as their natural solubilizing mechanisms
reduce the need for chemical fertilizers, mitigate environmental risks, and promote
sustainable agricultural practices. Future research should explore large-scale
applications and interactions between PSB and different crops to enhance nutrient
uptake and optimize crop yields.
Keywords: Phosphorus, phosphorus-solubilizing, samples, bacterial