Role of the interspecific interactions in the evolution of mutator bacteria

LUJAN, ADELA M; SOMMER LEA M.; MARVIG RASMUS L.; SHARMA, MD; SMANIA ANDREA; MOLIN, SOEREN; BUCKLING, ANGUS

Mar del Plata

Congreso; LI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2015

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Mutator bacteria can reach high frequencies in natural bacterial populations and are a major cause of antibiotic- resistant infections. The causes and consequences of bacterial elevated mutation rates have been widely studied and results suggest that mutators might be selected because their higher probability of generating beneficial mutations. However, this evidence is based on pure test-tube studies that have largely ignored a crucial feature of the environment: the microbial community (MC). Here, we investigate for the first time the role of the MC in the selection of Pseudomonas aeruginosa mutators in a cystic fibrosis (CF) context. By competing P. aeruginosa non mutator and mutator strains in artificial CF communities (B. cenopacea, S. aureus and A.baumanii), we observed that mutator enrichment occurs only in the absence of the MC. Fitness determination of evolved strains suggest that the presence of the MC reduces the availability of beneficial mutations and might prevent mutator hitchhiking. Also, we conducted a survey to investigate whether there was a link between the MC diversity and P. aeruginosa mutation frequency in natural CF communities. We found a negative correlation between P. aeruginosa mutation frequency and MC diversity. Our results demonstrate that interspecific interactions occurring in CF microbial communities act as a selective force for P. aeruginosa mutators.