| Congresso Brasileiro de Microbiologia 2023 | Resumo: 308-1 | ||||
Resumo:Extreme environments drive the selection of microorganisms with highly adapted phenotypes that may contain genes of interest from a biotechnological perspective. This is the case for water storage tanks used to wash pesticide containers, an environment characterized by the presence of chemical substances that induce oxidative stress. The objective of this work is to evaluate the biotechnological potential of nine bacterial isolates from water used in the washing of pesticide packages that remain in collection bottles at room temperature for six years. According to the experimental design (Figure 1), tolerance tests were carried out for the herbicides Heat (saflufenacil) and Trop (glyphosate), the first present at the collection site and the second absent, at concentrations of 1, 10 and 50 times those used in agriculture.
Figure 1: Experimental design. Created with BioRender.com.
All isolates tolerated the heat concentrations. For Trop, only isolates 6, 7 and 8 (under the molecular identification process) tolerated all tested concentrations, showing the toxic potential of glyphosate-based herbicides. Here, prior selection seems to play an important role, as Heat was present at the isolation site. In addition, microbial growth monitoring tests were carried out using bacterial direct confrontation and bacterial culture supernatants against the opportunistic fungus Sclerotinia sclerotiorum and against opportunistic strains, ATCC reference, Bacillus subtilis 6633; Escherichia coli 25922; Klebsiella pneumoniae 13883; Proteus mirabilis 13883; Pseudomonas aeruginosa 27853 and Staphylococcus aureus 25923, looking for the formation of halos of growth. In direct bacterial challenge tests, isolates 2, 4, 5 and 9 inhibited S. sclerotiorum growth. Isolates 2 and 6 inhibited the growth of B. subtilis 6633, while 4, 5 and 9 inhibited the growth of E. coli 25922, K. pneumoniae 13883, P. mirabilis 25933 and S. aureus 25923, and 6, 7 and 8 inhibited the growth of P. aeruginosa 27853. These results indicate that there is activation of genes producing metabolites with antibiotic potential by isolates after stimulation by cell contact. Equivalent results were observed in the growth starter tests using bacterial culture supernatants only for the bacteria K. pneumoniae 13883 and P. mirabilis 13883, indicating that for these bacteria, the production of inhibitory metabolites may have been constitutive. The isolates studied in this work have potential for use in bioremediation and biological control programs, but they need to be better identified in terms of enzymes, herbicide tolerance, and antibiotic production. Palavras-chave: Microbial antagonism, secondary metabolites, selective pressure, tolerance Agência de fomento:Coordination for the Improvement of Higher Level Personnel (CAPES) | |||||