Interactions between biofilms and the environment

Authors

  • Terry J Beveridge,

    Corresponding author
    1. Canadian Bacterial Disease Network-National Centre of Excellence, Guelph, Ont. N1G 2W1Canada
    2. Canadian Institute of Advanced Research, College of Biological Sciences, Guelph, Ont. N1G 2W1Canada
    3. Department of Microbiology, College of Biological Sciences, University of Guelph, Guelph, Ont. N1G 2W1Canada
    Search for more papers by this author
  • Stephen A Makin,

    1. Canadian Institute of Advanced Research, College of Biological Sciences, Guelph, Ont. N1G 2W1Canada
    2. Department of Microbiology, College of Biological Sciences, University of Guelph, Guelph, Ont. N1G 2W1Canada
    Search for more papers by this author
  • Jagath L Kadurugamuwa,

    1. Canadian Bacterial Disease Network-National Centre of Excellence, Guelph, Ont. N1G 2W1Canada
    2. Department of Microbiology, College of Biological Sciences, University of Guelph, Guelph, Ont. N1G 2W1Canada
    Search for more papers by this author
  • Zusheng Li

    1. Canadian Bacterial Disease Network-National Centre of Excellence, Guelph, Ont. N1G 2W1Canada
    2. Department of Microbiology, College of Biological Sciences, University of Guelph, Guelph, Ont. N1G 2W1Canada
    Search for more papers by this author

Corresponding author. Tel.: +1 (519) 824-4120, ext. 3366; Fax: +1 (519) 837-1802; E-mail: tjb@micro.uoguelph.ca

Abstract

The surfaces of bacteria are highly interactive with their environment. Whether the bacterium is Gram-negative or Gram-positive, most surfaces are charged at neutral pH because of the ionization of the reactive chemical groups which stud them. Since prokaryotes have a high surface area-to-volume ratio, this can have surprising ramifications. For example, many bacteria can concentrate dilute environmental metals on their surfaces and initiate the development of fine-grained minerals. In natural environments, it is not unusual to find such bacteria closely associated with the minerals which they have helped develop. Bacteria can be free-living (planktonic), but in most natural ecosystems they prefer to grow on interfaces as biofilms; supposedly to take advantage of the nutrient concentrative effect of the interface, although there must also be gained some protective value against predators and toxic agents. Using a Pseudomonas aeruginosa model system, we have determined that lipopolysaccharide is important in the initial attachment of this Gram-negative bacterium to interfaces and that this surface moiety subtly changes during biofilm formation. Using this same model system, we have also discovered that there is a natural tendency for Gram-negative bacteria to concentrate and package periplasmic components into membrane vesicles which bleb-off the surface. Since some of these components (e.g., peptidoglycan hydrolases) can degrade other surrounding cells, the vesicles could be predatory; i.e., a natural system by which neighboring bacteria are targeted and lysed, thereby liberating additional nutrients to the microbial community. This obviously would be of benefit to vesicle-producing bacteria living in biofilms containing mixed microbial populations.

Ancillary