Genetic and nutritional diversity of Bacillus subtilis isolates demonstrating different aspects related to plant growth promotion
Currently, agricultural practices have been undergoing intense transformations, imposing major challenges such as maintaining productivity with lower production costs and environmental impacts. One of the alternatives to meet these requirements is the use of plant growth promoting bacteria, including Bacillus subtilis. However, different isolates may express different aspects and levels of plant growth promotion. The present study aimed to verify the genetic and nutritional diversity of eight B. subtilis isolates, demonstrating different aspects and levels of plant growth promotion. Eight B. subtilis isolates were analyzed as to their nutritional diversity by BiologEcoPlate TM kit, genetic diversity by Box-PCR, and a trial in greenhouse conditions. The experimental design in greenhouse trial was completely randomized with 9 treatments and five replicates, resulting in 45 pots. Treatments were eight Bacillus subtilis strains, and a control treatment using plants without bacterial inoculation. Isolates 290 and 287 are genetically similar, while isolates 248 and 263 also showed similarity. Genetic and substrate consumption (carbon) analyses showed differences and similarities among isolates, allowing the distribution of isolates into different groups. It was observed that the isolate with the highest ability to promote plant growth was the only isolate that consumed glycyl-L- glutamic acid. These results open the way for further investigations in an attempt to clarify what are the conditions and / or characteristics required by isolates for the plant growth promotion to be more effective.