| Congresso Brasileiro de Microbiologia 2023 | Resumo: 845-1 | ||||
Resumo:
Pseudomonas aeruginosa is a Gram-negative bacterium and an important model microorganism for the study of bacterial biofilms. It is an opportunistic pathogen considered by the World Health Organization (WHO) as a critical epidemiological priority due to multidrug-resistant strains. In addition to biofilms, swarming motility also plays an important role in pathogenicity and antimicrobial resistance for many species of bacteria, including P. aeruginosa. P. aeruginosa produces biosurfactants that modulate swarming motility. The rhamnolipid-type biosurfactants produced by this bacterium has a relevant potential for industrial and environmental applications. Among the biosurfactants produced by P. aeruginosa, the three most abundant are 3-(3-hydroxyalkanoyloxy) alkanoic acid (HAA), L-rhamnosyl-3-hydroxydecanoyl-3-hydroxydecanoate (mono-rhamnolipid) and L-rhamnosyl-L- rhamnosyl-3-hydroxydecanoyl-3-hydroxydecanoate (di-rhamnolipid). HAA is synthesized through the activity of the RhlA enzyme, being converted into mono-rhamnolipid by the RhlB enzyme, and into di-rhamnolipid by the RhlC enzyme. RhlA is therefore a key enzyme in the production of both rhamnolipids. Evidence in the literature suggests that rhamnolipids and flagella are essential for motility in P. aeruginosa, particularly the swarming motility. However, the role assigned to rhamnolipids is restricted to physical-chemical aspects, related to their surface and interfacial tension reduction properties. The biochemical and molecular mechanisms involved in the action of rhamnolipids in swarming motility are still unclear. Previous results from our research group involving transcriptomic analysis of non-adherent cells suggest a possible regulatory pattern of gene expression mediated by rhamnolipids. In the current study, our aim was to investigate the gene expression profile during swarming motility in P. aeruginosa PAO1 and its rhamnolipid-deficient mutants. Differentially expressed genes in the global transcriptomic assays were selected, which include genes involved in flagellar and type IV fimbriae biogenesis. Swarming assays were performed for phenotypic analysis and total RNA extraction from swarming edges. Subsequently, molecular analysis was performed using RT-qPCR. The flagellar genes fliC, fliD, fliT and flgL were significantly repressed in the rhlA-negative strain, compared to the wild-type strain PAO1, with its expression totally or partially restored by supplementation with exogenous rhamnolipids. The pilO and hcp1 genes also showed a decrease in expression, in a similar fashion to the repression profile observed for the flagellar genes. We hope to contribute to a better understanding of the molecular mechanisms involved in the regulatory dynamics of rhamnolipids on the swarming motility and other social phenotypes in P. aeruginosa PAO1.
Palavras-chave: Pseudomonas aeruginosa, swarming, real-time PCR (RT-qPCR) Agência de fomento:Development Agency: Petróleo Brasileiro S.A. (Petrobras) | |||||