| Congresso Brasileiro de Microbiologia 2023 | Resumo: 868-1 | ||||
Resumo:Probiotics are biotherapeutic products that can mitigate damage caused by dysbiosis and that have been gaining greater prominence in the prevention and remediation of human and animal health. However, current probiotics have characteristics that still need to be optimized, such as colonization capacity in the target organism and rejection of probiotics by the host and its microbiota. Thus, this study aims to develop probiotic strains for application in birds of economic value while seeking to understand the ecological and evolutionary characteristics involved in the intestinal microbiota of vultures. To achieve this objective, one hundred colony-forming units bacterias were selected from vulture feces. A competitive inhibition method was used with the vulture isolates against the ATCC opportunistic strains Bacillus subtilis 6633, Escherichia coli 25922, Pseudomonas aeruginosa 27853, and Staphylococcus aureus 25923. The isolates that showed greater capacity to inhibit opportunistic strains were selected to form bacterial pools and tested again against opportunistic strains. For a better understanding of the results obtained through the competitive inhibition tests, a set with two vulture isolates was chosen, the U97 isolate, which inhibited three opportunists, and another isolate which did not inhibit any, and one of the opportunistic strain. Subsequently, the 16S rDNA gene of these two isolates was sequenced and the Quorum Sensing signaling molecules analyzed using Liquid Chromatography Coupled to Mass Spectrometry (LC-MS/MS). Competitive inhibition tests against ATCC opportunistic strains showed two levels of inhibition, complete and partial. From the evaluated collection, 44 isolates inhibited B. subtilis, 23 inhibited E. coli, 42 inhibited P. aeruginosa, and 50 isolated inhibited S. aureus. Of the 100 bacteria in the collection, 52 isolates could inhibit more than 1 ATCC strain. The tests of bacterial sets showed different results from those presented by the tests of separate isolates. Of the 113 tests in sets, 5 showed complete inhibition, 23 partial, and 85 failed to inhibit the opportunistic strains. These preliminary results showed that in the black vulture microbiota there are bacteria that can produce antimicrobials peptides (AMPs) against opportunistic strains, but when these same bacteria are in sets, the inhibition capacity decreases considerably. Swarming mechanisms have been observed in B. subtilis responding to competition in the presence of inhibitory bacteria, but not when the inhibitory bacteria are in pools. The hypothesis raised is that when the inhibitor bacteria were alone, the virulence mechanism was activated, generating AMPs, and in the same way, the opportunistic strain B. subtilis activated this swarming mechanism caused by competition with its inhibitor bacteria. However, when taken in sets, both mechanisms were deactivated. The another isolate from microbiota could have caused gene silencing due to its presence, and the second case could be caused by the lack of need for B. subtilis to avoid antimicrobial products, since the inhibitor isolates no longer produced it. The LC-MS/MS results can clarify, demonstrating the presence or not of specific QS molecules that have such capacities linked to these mechanisms observed in the bacteria studied, or even associate a new signaling molecule with the production of AMPs, since bacteria can express genes related to these molecules in response to QS. Palavras-chave: Biotechnological Improvement, Competitive Exclusion, Gut Microbiome, Quorum sensing | |||||