| Congresso Brasileiro de Microbiologia 2023 | Resumo: 351-2 | ||||
Resumo:Plant growth-promoting bacteria (PGPB) are microorganisms capable of colonizing a specific plant species or even a soil associated with it. This microbial ecological characteristic greatly favors the target plant species, since it provides greater productivity. PGPBs favor plants by different biochemical mechanisms and often produce and secrete proteolytic enzymes. Due to the ecological importance of PGPBs and the biotechnological relevance of proteases, this work focused on the analysis of the potential for protease production by bacteria collected from three different soils in the Campos Gerais region, Paraná. The different samples (soil and roots) were homogenized in sterile saline solution, diluted and incubated in 10% Tryptic Soy Broth (TSB) at 28°C and 65°C for 24 hours, to enrich the microbiota present. The proteolytic activity of the isolates was screened by plating them into two different types of Skim Milk Agar at 28°C. The isolates with the highest ratio of the proteolytic degradation zone to the colony diameter were subcultured in 10% TSB at 28°C under agitation, for 24 hours and 48 hours. After incubation, the cultures were centrifuged for bacterial cell sedimentation and the supernatants were submitted to casein degradation assays (caseinolysis) and revealed by the Bradford method. Both 24-hour and 48-hour supernatants were tested at pH 7.0, pH 8.0 and pH 9.0, using 50mM Tris-HCl buffer and 0.05 mg/mL casein. Of the tested isolates, three showed good casein degradation profiles and were named: PR03, from the school farm of the State University of Ponta Grossa; PR17, from an environmental preservation area; PR25, from an area of agricultural activity. PR03 showed maximum proteolytic activity at pH 8.0 after 48 hours of growth, while PR17 and PR25 showed higher protease secretion with 24 hours of growth, but with optimal activity values at pHs 8.0 and 7.0 respectively. Partial sequencing of the 16S rRNA strongly indicated that PR03, PR17 and PR25 represent strains of the genera Priestia, Bacillus and Burkholderia respectively. These results reinforce the particularity of the microbiota present in the soils of the Campo Gerais region and open the possibility for deeper biochemical investigations for these and other proteases produced by PGPBs. Palavras-chave: Proteases, enzymes, plant growth-promoting bacteria Agência de fomento:CAPES; CNPQ; FUNDAÇÃO ARAUCÁRIA | |||||