AUTHOR=Periasamy Saravanan , Nair Harikrishnan A. S. , Lee Kai W. K. , Ong Jolene , Goh Jie Q. J. , Kjelleberg Staffan , Rice Scott A. 

TITLE=Pseudomonas aeruginosa PAO1 exopolysaccharides are important for mixed species biofilm community development and stress tolerance

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.00851

DOI=10.3389/fmicb.2015.00851

ISSN=1664-302X

ABSTRACT=<p><italic>Pseudomonas aeruginosa</italic> PAO1 produces three polysaccharides, alginate, Psl, and Pel that play distinct roles in attachment and biofilm formation for monospecies biofilms. Considerably less is known about their role in the development of mixed species biofilm communities. This study has investigated the roles of alginate, Psl, and Pel during biofilm formation of <italic>P. aeruginosa</italic> in a defined and experimentally informative mixed species biofilm community, consisting of <italic>P. aeruginosa</italic>, <italic>Pseudomonas protegens</italic>, and <italic>Klebsiella pneumoniae</italic>. Loss of the Psl polysaccharide had the biggest impact on the integration of <italic>P. aeruginosa</italic> in the mixed species biofilms, where the percent composition of the <italic>psl</italic> mutant was significantly lower (0.06%) than its wild-type (WT) parent (2.44%). In contrast, loss of the Pel polysaccharide had no impact on mixed species biofilm development. Loss of alginate or its overproduction resulted in <italic>P. aeruginosa</italic> representing 8.4 and 18.11%, respectively, of the mixed species biofilm. Dual species biofilms of <italic>P. aeruginosa</italic> and <italic>K. pneumoniae</italic> were not affected by loss of alginate, Pel, or Psl, while the mucoid <italic>P. aeruginosa</italic> strain achieved a greater biomass than its parent strain. When <italic>P. aeruginosa</italic> was grown with <italic>P. protegens</italic>, loss of the Pel or alginate polysaccharides resulted in biofilms that were not significantly different from biofilms formed by the WT PAO1. In contrast, overproduction of alginate resulted in biofilms that were comprised of 35–40% of <italic>P. aeruginosa</italic>, which was significantly higher than the WT (5–20%). Loss of the Psl polysaccharide significantly reduced the percentage composition of <italic>P. aeruginosa</italic> in dual species biofilms with <italic>P. protegens</italic> (&lt;1%). Loss of the Psl polysaccharide significantly disrupted the communal stress resistance of the three species biofilms. Thus, the polysaccharide composition of an individual species significantly impacts mixed species biofilm development and the emergent properties of such communities.</p>