Population dynamics and transcriptomic responses of Pseudomonas aeruginosa in a complex laboratory microbial community

Abstract

Pseudomonas aeruginosa is one of the dominant species when it co-exists with many other bacterial species in diverse environments. To understand its physiology and interactions with co-existing bacterial species in different conditions, we established physiologically reproducible eighteen-species communities, and found that P. aeruginosa became the dominant species in mixed-species biofilm community but not in the planktonic community. P. aeruginosa H1 type VI secretion system was highly induced in the mixed-species biofilm community compare to its mono-species biofilm, which was further demonstrated to play a key role for P. aeruginosa to gain fitness over other bacterial species. In addition, the type IV pili and Psl exopolysaccharide were shown to be required for P. aeruginosa to compete with other bacterial species in the biofilm community. Our study showed that the physiology of P. aeruginosa is strongly affected by interspecies interactions, and both biofilm determinants and H1 type VI secretion system contribute to P. aeruginosa fitness over other species in complex biofilm communities.\n\nImportancePseudomonas aeruginosa usually coexists with different bacterial species in natural environment. However, systematic comparative characterization of P. aeruginosa in complex microbial communities with its mono-species communities is lacking. We constructed mixed-species planktonic and biofilm communities consisting P. aeruginosa and seventeen other bacterial species to study the physiology and interaction of P. aeruginosa in complex multiple-species community. A single molecule detection platform, NanoString nCounter(R) 16S rRNA array, was used to shown that P. aeruginosa can become the dominant species in the biofilm communities while not in the planktonic communities. Comparative transcriptomic analysis and fluorescence-based quantification further revealed that P. aeruginosa H1 type VI secretion system and biofilm determinants are both required for its fitness in mixed-species biofilm communities.