COMPENSATORY MUTATIONS IN C-DI-GMP PATHWAYS UNDERLIES Pseudomonas aeruginosa ADAPTATION TO BIOFILMS

TOBARES RA; SMANIA AM

Mar del Plata

Congreso; LI Reunión Anual de la Sociedad Argentina de Investigaciones Bioquímicas y Biología Molecular, SAIB; 2015

Pseudomonas aeruginosa is able to grow in communities known as biofilms. Small Colony Variants (SCV), one ofthe adapted morphotypes that arise from biofilm cultures, have been characterized as small size colonies formed byhyperadherent and highly biofilm producer cells. When SCV are grown on solid media, wild type-like morphotypesemerge at the edge of the colonies, which also show reversion of SCV phenotypic traits. In this work, we analyzedthe adaptability of P. aeruginosa by carrying out a long-term assay of experimental evolution followed by wholegenomesequencing. Three lines of P. aeruginosa PA14 were subjected to alternating and successive cycles ofbiofilm growth (conversion) and growth in solid media (reversion). In each line, whole genomes of the ancestral andof the most evolved clones were sequenced. We observed the acquisition of one non-synonymous mutation per round of evolution. Strikingly, most of these mutations were found in genes of the wsp and yfi operons, coding forchemosensory systems involved in biofilm formation through the modulation of c-di-GMP levels. So far, our resultsindicate that, in our experimental evolutionary assay, the adaptability of P. aeruginosa to repeated cycles of SCVconversion/reversion is based on compensatory spontaneous mutations that produce variations in the intracellularlevels of c-di-GMP.