Phenotypic diversification and hypermutability in Pseudomonas aeruginosa biofilms

TOBARES RA; SMANIA AM

Rosario

Congreso; L Reunión Anual de la Sociedad Argentina de Investigaciones Bioquímicas y Biología Moleculari; 2014

Biofilm (BF) growth is one of the adaptive strategies through which Pseudomonas aeruginosa (PA) can adhere to inert or host surfaces. During BF growth PA undergoes phenotypic diversification that leads to the emergence of different niche specialists. We have previously shown that BF formed by a mutS mutator strain displays a higher diversification than wild type (WT). Competition experiments showed that the mutS strain has a higher fitness than WT. Here, we focused on Small Colony Variants (SVC), one of the BF-adapted morphotypes. We observed that when SCV were grown in solid media, the WT-like morphotype emerged from the colony edges. The relative fitness of SCV derived either from WT or mutS was higher than the respective ancestor strain. Similarly, the SCV outcompete the reverted morphotypes. These results give further evidences that SCV had acquired adaptive traits to BF growth. Moreover, to confirm if the increased fitness of the mutS strain was related to a higher diversification we performed a complementation experiment with a plasmid harboring a functional mutS gene. Diversification in the complemented strain was similar to WT and no significant differences were found in relative fitness between them. In conclusion, these our results confirm indicate that the advantage of mutS strain in BF is due to a higher probability of generating adaptive morphotypes in this environment.