Phosphate Soluting Actinomycetes In The Rhizosfer Of Corn (Zea Mays) Plant In Gorontalo

Actinomycetes are Gram-positive bacteria with morphological characteristics in the form of unicellular filaments that have the potential to dissolve bound phosphate into a form available to plants. This study aims to isolate and identify phosphate-solubilizing Actinomycetes from the rhizosphere of corn (Zea mays) in Gorontalo, Indonesia. Rhizosphere soil samples were taken at a depth of 15-30 cm from three corn farming locations in Mohiyolo Village, Asparaga District. Parameters analyzed included environmental characteristics, isolate morphology, phosphate solubility index, and soluble phosphate concentration. Identification was based on the morphology of aerial mycelium and substrate mycelium, as well as physiological tests of phosphate solubilization ability. Phosphate solubility index was calculated from the ratio of halo zone diameter to colony on Pikovskaya agar medium, while soluble phosphate concentration was measured using spectrophotometry. The results showed that RFZm-Pg isolate had the highest solubility index of 2.98 mm, while RFZm-Pw isolate was 1.54 mm. The highest dissolved phosphate concentration in liquid media was 2.0929 ppm (RFZm-Pg) and 1.0744 ppm (RFZm-Pw). The phosphate-solubilizing Actinomycetes isolates obtained have potential as biofertilizers, so further testing is needed.