Two Isolates From Plants Cultivated in Red Lateritic Soils are Good Candidates for the Development of Microbial Biostimulants

Abstract

Phosphorus is essential for plant growth, yet its availability in soils is extremely limited, with less than 0.1% accessible toplants. Though phosphate fertilizers are frequently employed to address this deficiency, a significant portion of the appliedphosphorus is quickly fixed and unavailable to plants. Thus, the use of plant growth-promoting bacteria (PGPB) capableof solubilizing insoluble phosphate is an increasingly accepted eco-friendly agricultural practice to enhance phosphorusavailability. This study aimed to isolate native phosphorus-solubilizing bacteria from lateritic and sandy soils of Misionesand Corrientes provinces (Argentina) and to study their plant growth-promoting attributes. Among the 17 isolates obtainedfollowing a selective protocol, two isolates, here named BVP24 and MMBR01, exhibited the highest phosphate solubilizationactivity (greater than other reported microorganisms) and produced substantial amounts of indole acetic acid. Both isolateswere identified as Priestia megaterium via MALDI-TOF analysis and inhibited in vitro Fusarium graminearum growth.MMBR01 additionally inhibited Bipolaris sorokiniana growth. A dose of 1 × 106CFU per seed was the most efficient topromote root dry weight in maize seedlings. Based on their plant growth-promoting capacities, these native strains emergeas potential biofertilizers, offering an alternative to synthetic phosphate fertilizers and contributing to more sustainablephosphorus management.