Bioprospecção de bactérias promotoras de crescimento vegetal (BPCV) aplicadas ao cultivo de feijão (Phaseolus vulgaris L.)

Abstract

Agricultural industrialization, which occurred throughout the 20th century, increased productivity and ensured a greater food supply, but it also brought undesirable environmental and social impacts, particularly through the intensive use of fertilizers, herbicides, and pesticides, which affected various ecosystems and biodiversity. Therefore, the need for sustainable alternatives to maintain agricultural practices is highlighted, such as plant growth-promoting bacteria (PGPB), which represent a promising solution to reduce the negative effects of the excessive use of chemical inputs. In this context, this study aimed to identify bioprospected plant growth-promoting bacteria in common bean (Phaseolus vulgaris L.) roots and the associated rhizosphere soil. To this end, the capacity of bacterial isolates to act as PGPB was evaluated, using direct mechanisms, such as nitrogen fixation, inorganic phosphate and potassium solubilization and phytohormone production (auxins), as well as indirect mechanisms, such as biological control of phytopathogenic fungi. Subsequently, promising bacteria were identified using molecular techniques and their potential to improve bean development was assessed by inoculating bean seeds. Thirty-two bacteria were isolated from bean plants and the associated rhizosphere soil. Of these, six excelled in biochemical tests aimed at evaluating their potential to promote plant growth. The selected isolates were: LR5 (identified as Enterobacter sp.), TS4, TS7, TR2, TR4 (identified as Citrobacter sp.) and TR6. Due to the lack of sequencing success, it was not possible to identify TS4, TS7, TR2 and TR6. Inoculation with this BPCV resulted in increases in plant morphometric parameters, including shoot height, root length and fresh and dry biomass of vegetative structures, compared to the uninoculated control. Among the isolates evaluated, LR5 and TR2 performed best in all analyzed parameters. For future studies, it is recommended to carry out additional tests under field conditions, identify strains at the species level and evaluate the potential of microbial consortia, contributing to the development of technologies for sustainable agriculture.