Assessment of Phosphate Solubilization, Indole Acetic Acid and Ammonia Production by Bacteria and Fungi Isolated from the Rhizosphere of Guinea Corn (Sorghum bicolor)

The rhizosphere is known to harbour a number of bacteria and fungi that can improve plant growth and productivity. This study investigated the abilities of bacteria and fungi isolated from the rhizosphere of guinea corn to solubilize phosphate, Idole Acetic Acid (IAA) and ammonia production. Purified isolates were confirmed through biochemical test and Gram staining. Phosphate solubilization was quantified using Pikovskaya’s, medium on standardized isolates using standard curve. IAA, production was observed using spectrophotometer and ammonia production was confirmed using Mcfaland standard. Serratia marcescens, exhibited the highest phosphate solubilization activity (547.52 ug/ml), while Micrococcus luteus, exhibited the least (1.45 ug/ml). However, Escherichia coli, had the highest (1821.4 ug/ml), IAA, production and Serratia marcescens had the least (100.71ug/ml). Bacillus licheniformis, had the highest ammonia production (2452.65 ug/ml), while Lactobacillus bulgaricus, had the least (1495.77 ug/ml). Among the fungal isolates, Aspergillus niger had the highest phosphate solubilization effects (679.31ug/ml), while Mucor pusillus had the least ((1.82 ug/ml). Ammonia production was observed from all isolates screened. B. lichiniformis had the highest (2452.65ug/ml) and L. bulgaricus, had the least (1495.77ug/ml). The findings imply that rhizosphere soil of guinea corn harbours bacteria and fungi which can help to improve the availability of solubilized phosphate, production of IAA and ammonia. Keywords: Rhizosphere, phosphate solubilization, IAA, Guinea corn