| Congresso Brasileiro de Microbiologia 2023 | Resumo: 642-1 | ||||
Resumo:Bioprospecting plant growth-promoting bacteria is a research area seeking to identify and use beneficial microorganisms to improve plant development and performance. Among bacteria, the genus Bacillus is the most used as biofertilizers and biostimulants in commercial products due to its wide distribution in nature, metabolic diversity, and capacity to produce spores. These traits ensure its efficiency in promoting plant growth through different mechanisms such as nitrogen fixation, phosphate solubilization, and nutrient
absorption. In addition, Bacillus species produce phytohormones such as auxins, which can stimulate root growth and increase plant resistance to biotic and abiotic stresses. The present work aimed to characterize 28 Bacillus isolates from the Collection of Multifunctional and Phytopathogenic Microorganisms of Embrapa Maize and Sorghum (CMMF-MS) as plant growth promoters. The experiments were conducted on a bench scale through organic and inorganic phosphorus (P) solubilization tests in Phytate and Pikovskaya media. We also evaluated the exopolysaccharides production (EPS), biofilm formation, and synthesis of indole acetic acid (IAA). The bacterial isolates were categorized based on their ability to solubilize P using a solubilization index (SI), calculated by dividing the observed solubilization halo size by the colony diameter. The higher the IS, the greater the phosphorus solubilization capacity. Regarding biofilm formation, the isolates were classified using a colorimetric method and categorized as non-training, weakly forming, moderately formative, and powerfully formative based on the intensity of the observed staining. Of the 28 isolates tested, 17 showed halo formation in the Phytate medium, with IS ranging from 1.0 to 2.0. In the Pikovskaya medium, 14 isolates showed halo formation with IS ranging from 1.0 to 2.1. From the solubilization test, the isolate GSRM-2 stood out with solubilization indexes of 2.0 and 1.9 in Phytate and Pikovskaya medium, respectively. Only three isolates did not show EPS formation (GSC-19, GSS7-34, and SC1-8). As for biofilm formation, the values ranged from 1.1 (weakly forming) to 4.1 (strongly forming), highlighting the isolated SSMANG-14 classified as strongly forming, and SC1-2, SC1-4, SC1-8, SSMANG-16, SSRM-4, SSJAMB-10, SSRM-3, TSRM-5, NBSC-70, and SSC-1 classified as moderately forming. For IAA synthesis, the isolates GSS7-52, GSS7-92, GSS731, and GRSM-25 expressed the highest values, being 11.60μg mL-1, 10.14μg mL-1, 9.25μg mL-1 and 8.59μg mL-1 of IAA, respectively. The values obtained in this study indicate that the Bacillus tested have characteristics that can be used to promote plant growth. These results highlight the possibility of in vivo inoculation studies and bioformulation development.
Keywords: bacteria, biofertilizers, bioestimulants, productivity.
Development Agency: Embrapa Milho e Sorgo/ CNPq Palavras-chave: bacteria, bioestimulants, biofertilizers, productivity Agência de fomento:Embrapa Milho e Sorgo/ CNPq | |||||