Análise funcional da bactéria tb3 isolada da rizosfera do tamboril (Enterolobium contortisiliquum) e avaliação do potencial como bioinsumo agrícola

Abstract

Rhizobacteria are microorganisms that colonize the rhizosphere and provide beneficial effects to plants through different mechanisms, such as phytohormone synthesis, mineral solubilization, nitrogen fixation, and enhanced nutrient uptake. The use of microbial inoculants has gained prominence in recent decades for strengthening the biological component of production systems, reducing dependence on synthetic fertilizers, and contributing to agricultural sustainability. In this context, the present study aimed to confirm whether a bacterium isolated from the rhizosphere of Tamboril exhibits characteristics of a plant growth–promoting microorganism, as well as to evaluate its growth in a commercial medium and in alternative media formulated from watermelon products and by-products. The TB3 bacterium was characterized regarding its capacity for phosphate solubilization, biological nitrogen fixation, and production of indole-3-acetic acid (IAA). Subsequently, microbial growth kinetics were evaluated in nutrient broth and in an alternative medium based on watermelon juice, as well as the influence of pH, total reducing sugar concentration, and temperature on cell growth and IAA production. Cultivations were also performed with different concentrations of watermelon juice and in media formulated from the liquid and solid fractions of the fruit peel. The results indicated that TB3 presents functional characteristics compatible with plant growth–promoting microorganisms, in addition to satisfactory growth in alternative media formulated with watermelon juice and peel. The use of watermelon residue proved to be viable for bacterial cultivation, demonstrating potential for cost reduction and reuse of agro-industrial residues. Bioinoculant assays showed positive effects on the initial development of plants, especially when the application occurred after germination. Therefore, this study highlights the potential of the TB3 bacterium for use as an agricultural bioinoculant associated with sustainable strategies for the valorization of plant residues.