| Congresso Brasileiro de Microbiologia 2023 | Resumo: 642-2 | ||||
Resumo:The aerial roots of maize are often covered by a viscous and thick substance, mucilage, which is released by the epidermal cells, this substance plays an important role in the protection and absorbtion of nutrients of the plants. Mucilage is known to host communities of bacteria that establish a symbiotic relationship with plants, assisting in plant growth and development through biological nitrogen (N) fixation and phosphorus (P) solubilization. This mucilage occurs primarily when the plant is in its flowering stage, a period when the plant requires a greater amount of nutrients, specifically N and P. These nutrients are in high demand by the plant, especially N, and there is a strong reliance on external and costly synthetic sources for fertilizing this grass. Based on this, the present study aimed to bioprospect unidentified
bacterial isolates from maize mucilage for their plant growth-promoting properties. A quantity of mucilage was collected from the aerial roots of maize hybrids 115 T10 and 210 T5 from Embrapa Maize and Sorghum – Sete Lagoas to isolate the bacteria present in the mucilage, 32 isolates were selected for
the experiment. This experiment was conducted on a laboratory scale through tests for organic P solubilization in Phytate medium and inorganic P solubilization in Pikovskaya medium, as well as tests for biological nitrogen fixation. To categorize the isolates based on their phosphorus solubilization
capacity, the Solubilization Index (SI) was used. This index was calculated by dividing the size of the solubilization halo observed by the colony diameter. The isolates were analyzed after 6 days of growth and classified as strains with low solubilization (SI < 2), medium solubilization (2 ≤ SI ≤ 4), and high
solubilization (SI > 4). Regarding biological nitrogen fixation, a semi-solid NFB medium was used to observe possible film formation over a period of 24 hours and 72 hours. Out of the 32 isolates tested, in the Phytate medium, 17 isolates showed SI ranging from 1.08 to 2.76. In the Pikovskaya medium, 12 isolates exhibited halo formation with SI ranging from 1.33 to 2.26. Among these, isolate YM2-23a stood out with solubilization indices of 2.76 in the Phytate medium and 2.26 in the Pikovskaya medium, classifying it as a medium solubilization strain. Regarding biological nitrogen fixation, 7 isolates showed film formation in the NFB medium, with isolates YM2-5b, YM2-5c, YM2-28b, YM2-32, YM2-41, and YM2-1 forming films in 24 hours, and YM2-26 forming a film in 72 hours. The results obtained in this study indicate that bacteria isolated from the aerial root mucilage of maize possess desirable characteristics for promoting plant growth, making them suitable candidates for further in vivo inoculation studies in programs aimed at improving nutrient utilization efficiency. Palavras-chave: Grassy, Nutrients , Productivity, Sustainability Agência de fomento:Embrapa Milho e Sorgo/ CNPq | |||||