Root Microbes (Rhizobium tropici and Bacillus safensis) from Wild Tallgrass: for Agricultural and Environmental Applications

Indigenous plant growth-promoting bacteria (PGPB) associated with wild grasses represent potential microbial resources for sustainable agriculture. This study aimed to isolate, identify, and functionally characterize indigenous PGPB from the roots of Saccharum spontaneum collected near Department of Agriculture-Cagayan Valley Research Center (DA-CVRC), Brgy. Camunatan, City of Ilagan, Isabela, Philippines. Standard microbiological, biochemical, and molecular techniques identified the isolates as Rhizobium tropici and Bacillus safensis. Both isolates exhibited potential nitrogen-fixing activity and demonstrated phosphorus and potassium solubilization under in vitro conditions. R. tropici and B. safensis showed phosphorus solubilization indices of 2.2 and 2.7, respectively, indicating moderate phosphate-solubilizing capability. For potassium solubilization, R. tropici exhibited a higher solubilization index of 4.5, classified as a high potassium solubilizer, while B. safensis showed a moderate solubilization index of 2.4. The findings provide evidence that indigenous bacteria associated with S. spontaneum rhizospheres in the Philippines possess functional traits relevant to nutrient mobilization and biofertilizer development. This study highlights the local ecological significance of S. spontaneum as a potential reservoir of agriculturally beneficial microorganisms and demonstrates the potential of the isolates as indigenous biofertilizer candidates pending further greenhouse and field validation.