The role of quorum sensing mediated developmental traits in the resistance of Serratia marcescens biofilms against protozoan grazing

Authors

  • Shu-Yeong Queck,

    1. School of Biotechnology and Biomolecular Sciences,
    2. Centre for Marine Biofouling and Bio-Innovation, University of New South Wales, Sydney, NSW 2052, Australia.
    Search for more papers by this author
  • Markus Weitere,

    1. School of Biotechnology and Biomolecular Sciences,
    2. Centre for Marine Biofouling and Bio-Innovation, University of New South Wales, Sydney, NSW 2052, Australia.
    Search for more papers by this author
    • Present address: Zoological Institute, Department of General Ecology and Limnology, University of Cologne, 50923 Cologne, Germany.

  • Ana María Moreno,

    1. School of Biotechnology and Biomolecular Sciences,
    2. Centre for Marine Biofouling and Bio-Innovation, University of New South Wales, Sydney, NSW 2052, Australia.
    Search for more papers by this author
  • Scott A. Rice,

    1. School of Biotechnology and Biomolecular Sciences,
    2. Centre for Marine Biofouling and Bio-Innovation, University of New South Wales, Sydney, NSW 2052, Australia.
    Search for more papers by this author
  • Staffan Kjelleberg

    Corresponding author
    1. School of Biotechnology and Biomolecular Sciences,
    2. Centre for Marine Biofouling and Bio-Innovation, University of New South Wales, Sydney, NSW 2052, Australia.
      *E-mail s.kjelleberg@unsw.edu.au; Tel. (+61) 2 9385 2102; Fax (+61) 2 9385 1779.
    Search for more papers by this author

*E-mail s.kjelleberg@unsw.edu.au; Tel. (+61) 2 9385 2102; Fax (+61) 2 9385 1779.

Summary

Resistance against protozoan grazers is a crucial factor that is important for the survival of many bacteria in their natural environment. However, the basis of resistance to protozoans and how resistance factors are regulated is poorly understood. In part, resistance may be due to biofilm formation, which is known to protect bacteria from environmental stress conditions. The ubiquitous organism Serratia marcescens uses quorum sensing (QS) control to regulate virulence factor expression and biofilm formation. We hypothesized that the QS system of S. marcescens also regulates mechanisms that protect biofilms against protozoan grazing. To investigate this hypothesis, we compared the interactions of wild-type and QS mutant strains of S. marcescens biofilms with two protozoans having different feeding types under batch and flow conditions. Under batch conditions, S. marcescens forms microcolony biofilms, and filamentous biofilms are formed under flow conditions. The microcolony-type biofilms were protected from grazing by the suspension feeder, flagellate Bodo saltans, but were not protected from the surface feeder, Acanthamoeba polyphaga. In contrast, the filamentous biofilm provided protection against A. polyphaga. The main findings presented in this study suggest that (i) the QS system is not involved in grazing resistance of S. marcescens microcolony-type biofilms; (ii) QS in S. marcescens regulates antiprotozoan factor(s) that do not interfere with the grazing efficiency of the protozoans; and (iii) QS-controlled, biofilm-specific differentiation of filaments and cell chains in biofilms of S. marcescens provides an efficient mechanism against protozoan grazing.

Ancillary