Harnessing indigenous PGPR to enhance soil phosphorus availability and maize growth

This study investigated indigenous plant growth-promoting rhizobacteria (PGPR) isolated from Nigerian soils for their potential to enhance phosphorus availability and promote maize (Zea mays L.) growth. Five bacterial isolates obtained from soil collected at the Federal University Oye-Ekiti field were screened for key plant growth-promoting traits, including phosphate solubilization, indole-3-acetic acid (IAA) production, ammonia production, and hydrolytic enzyme activities (α-amylase and pectinase). Two promising isolates, IS-4 and IS-5, were selected for molecular identification. Among them, IS-5 showed the strongest overall plant growth-promoting performance, exhibiting moderate phosphate solubilization (PSI = 2.90), the highest IAA production, ammonia production, and pectinase activity. IS-4 was selected as a representative isolate from the preliminary screening. Whole-genome sequencing identified IS-5 as Enterobacter hormaechei OYAS29 and IS-4 as Acinetobacter sp. OYAS30.A pot experiment was conducted to evaluate the effect of Enterobacter hormaechei OYAS29 on soil phosphorus availability and maize growth. Treatment with OYAS29 slightly increased available phosphorus in soil from 0.4905 ppm in the control to 0.4934 ppm. Inoculated maize plants also showed improved growth compared with the control, including increases in plant height (26.12%), stem girth (30.03%), leaf length (24.78%), root length (39.88%), and total biomass (58.69%). Overall, the results indicate that E. hormaechei OYAS29 has strong potential as an indigenous PGPR for sustainable maize production and improved phosphorus availability in soil.