title: No apparent costs for facultative antibiotic production by the soil bacterium Pseudomonas fluorescens Pf0-1.
abstract: BACKGROUND
  Many soil-inhabiting bacteria are known to produce secondary metabolites that can suppress microorganisms competing for the same resources. The production of antimicrobial compounds is expected to incur fitness costs for the producing bacteria. Such costs form the basis for models on the co-existence of antibiotic-producing and non-antibiotic producing strains. However, so far studies quantifying the costs of antibiotic production by bacteria are scarce. The current study reports on possible costs, for antibiotic production by Pseudomonas fluorescens Pf0-1, a soil bacterium that is induced to produce a broad-spectrum antibiotic when it is confronted with non-related bacterial competitors or supernatants of their cultures.
  
  
  RESULTS
  We measured the possible cost of antibiotic production for Pseudomonas fluorescens Pf0-1 by monitoring changes in growth rate with and without induction of antibiotic production by supernatant of a bacterial competitor, namely Pedobacter sp.. Experiments were performed in liquid as well as on semi-solid media under nutrient-limited conditions that are expected to most clearly reveal fitness costs. Our results did not reveal any significant costs for production of antibiotics by Pseudomonas fluorescens Pf0-1. Comparison of growth rates of the antibiotic-producing wild-type cells with those of non-antibiotic producing mutants did not reveal costs of antibiotic production either.
  
  
  CONCLUSIONS
  Based on our findings we propose that the facultative production of antibiotics might not be selected to mitigate metabolic costs, but instead might be advantageous because it limits the risk of competitors evolving resistance, or even the risk of competitors feeding on the compounds produced.
authors: Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands. p.garbeva@nioo.knaw.nl
authors: Paolina
authors: P
authors: Garbeva
authors: Olaf
authors: O
authors: Tyc
authors: Mitja N P
authors: MN
authors: Remus-Emsermann
authors: Annemieke
authors: A
authors: van der Wal
authors: Michiel
authors: M
authors: Vos
authors: Mark
authors: M
authors: Silby
authors: Wietse
authors: W
authors: de Boer
mesh_terms: D000362:Agar / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D046508:Culture Techniques; D015964:Gene Expression Regulation, Bacterial; D009154:Mutation; D011551:Pseudomonas fluorescens / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D012988:Soil Microbiology
chemical_list: D000900:Anti-Bacterial Agents; D000362:Agar