Chemical defense in marine biofilm bacteria

Carsten Matz, Jeremy S. Webb, Peter J. Schupp, Shui Yen Phang, Anahit Penesyan, Suhelen Egan, Peter Steinberg, Staffan Kjelleberg

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

Abstract

Many plants and animals are defended from predation or herbivory by inhibitory secondary metabolites, which in the marine environment are very common among sessile organisms. Among bacteria, where there is the greatest metabolic potential, little is known about chemical defenses against bacterivorous consumers. An emerging hypothesis is that sessile bacterial communities organized as biofilms serve as bacterial refuge from predation. By testing growth and survival of two common bacterivorous nanoflagellates, we find evidence that chemically-mediated resistance against protozoan predators is common among biofilm populations in a diverse set of marine bacteria. Using bioassay-guided chemical and genetic analysis, we identified one of the most effective antiprotozoal compounds as violacein, an alkaloid that we demonstrate is produced predominately within biofilm cells. Nanomolar concentrations of violacein inhibit protozoan feeding by inducing a conserved eukaryotic cell death program. Such biofilm-specific chemical defenses could contribute to the successful persistence of biofilm bacteria in various environments and provide the ecological and evolutionary context for a number of eukaryote-targeting bacterial metabolites. Predators are potent agents of mortality and natural selection in biological communities. Plants and animals synthesize a broad range of secondary metabolites that are deterrent or toxic to their consumers, thus functioning as defense compounds. Such chemicals are often common in sessile eukaryotic organisms such as marine sponges and corals, seaweeds and terrestrial plants [1-4], which lack escape or avoidance mechanisms. However, chemically-mediated antipredator defenses of bacteria and their ecological and evolution ary consequences remain a greatly understudied field. Particularly, the increasing number of biologically active compounds isolated from marine bacteria raises the question of their ecological functions [5].

Original languageEnglish
Title of host publicationEnvironmental chemistry
Subtitle of host publicationnew techniques and data
EditorsHarold H. Trimm, William Hunter III
Place of PublicationToronto; New York
PublisherApple Academic Press
Chapter9
Pages120-131
Number of pages12
ISBN (Print)9781926692777
Publication statusPublished - 2012
Externally publishedYes

Bibliographical note

Permissions of the book stated that "Chemical Defense in Marine Biofilm Bacteria was originally published as “Marine Biofilm Bacteria Evade Eukaryotic Predation by Targeted Chemical Defense” in PLoSONE 7:23, 2008. Reprinted with permission under the Creative Commons Attribution License or equivalent." The article actually published in 2008, PLoSONE 3(7): e2744. doi:10.1371/journal.pone.000274.

Keywords

  • Antiprotozoal activity
  • Bacterivorous
  • Biofilms
  • Microbulbifer
  • γ-proteobacteria

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