| Congresso Brasileiro de Microbiologia 2023 | Resumo: 10-1 | ||||
Resumo:Rhizosphere microbiomes are crucial components of the soil–plant continuum since they integrate a variety of microbial biological activities affecting plant development, as phosphate (P) solubilization and siderophore production. P-solubilizing microorganisms can solubilize and mineralize P from inorganic and organic pools, increasing P-availability to plants. Siderophores are low-molecular iron-chelating molecules; siderophore-producing bacteria can stimulate plant growth directly, improving plant Fe nutrition, or indirectly, inhibiting the activity of plant pathogens in the rhizosphere. The aim of this work was to evaluate the ability of phosphate solubilization and siderophore production by bacteria isolated from the rhizosphere of maize (Zea Mays), cultivated in three soils from different land use types: (1) Mixed Ombrophylous Forest; (2) a four-year restoration area, with long-standing record of use for agriculture; (3) agriculture. Soils were collected from 0–20 cm depth and maize seeds were planted in plastic pots with one of the soil samples. After 45 days of grown in a greenhouse, rhizospheric soils were used for serial dilution and inoculation onto solid NBRIP medium with Ca3(PO4)2. Of the strains that showed higher solubilization indexes in a shorter period of time, eighteen were selected. The 16S rDNA sequencing allowed their identification as belonging to genera Pseudomonas, Enterobacter, Achromobacter, Priestia, Rhodococcus, Bacillus, Stutzerimonas, Burkholderia and Pantoea. For the quantitative analysis of the P-solubilization, strains were grown in liquid NBRIP with Ca3(PO4)2 and the P-solubilized was measured based on the phosphomolybdate method. After 96h of incubation, the selected strains showed values ranging from 13.405 mg/L to 191.614 mg/L, accompanied by acidification of the pH of the medium. The six most efficient strains were identified as Pseudomonas (three strains), Stutzerimonas, Enterobacter and Pantoea (one of each genus), all from the forest and restoration areas; with exception of Pantoea all these efficient P-solubilizing strains were also siderophore producers. The other siderophore-producing bacteria, identified as Burkholderia sp. and Enterobacter sp., presented P-solubilization values between 58,935 mg/L and 59,857 mg/L. Since the bacteria that presented highest rates of P solubilization and siderophore production were isolated from regions of native vegetation and a soil under ecological restoration, our results suggest that non-agricultural soils can be biodiverse resources for biotechnological innovation. Palavras-chave: Phosphate solubilization, plant-growth promoting bacteria, land use, siderophore. Agência de fomento:CNPq; Fundação Araucária | |||||