title: Biofilm formation by avian Escherichia coli in relation to media, source and phylogeny.
abstract: OBJECTIVE
  To assess the abilities of 105 avian pathogenic Escherichia coli (APEC) and 103 avian faecal commensal E. coli (AFEC) to form biofilms on a plastic surface and to investigate the possible association of biofilm formation with the phylotype of these isolates.
  
  
  RESULTS
  Biofilm production was assessed in 96-well microtitre plates using three different media, namely, M63 minimal medium supplemented with glucose and casamino acids, brain-heart infusion broth, and diluted tryptic soy broth. Avian E. coli are highly variable in their ability to form biofilms. In fact, no strain produced a strong biofilm in all three types of media; however, most (75.7% AFEC and 55.2% APEC) were able to form a moderate or strong biofilm in at least one medium. Biofilm formation in APEC seems to be mostly limited to nutrient deplete media; whereas, AFEC are able to form biofilms in both nutrient deplete and replete media. Also, biofilm formation in E. coli from phylogenetic groups B2, D and B1 was induced by nutrient deplete conditions; whereas, biofilm formation by members of phylogenetic group A was strongest in a rich medium.
  
  
  CONCLUSIONS
  Biofilm formation by APEC and phylotypes B2, D and B1 is induced by nutrient deplete conditions, while AFEC are able to form biofilms in both nutrient rich and deplete media.
  
  
  CONCLUSIONS
  This is the first study to investigate biofilm formation by a large sample of avian E. coli isolates, and it provides insight into the conditions that induce biofilm formation in relation to the source (APEC or AFEC) and phylogenetic group (A, B1, B2 and D) of an isolate.
authors.affiliation: Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Skyberg
authors.forename: K E
authors.initials: KE
authors.lastname: Siek
authors.forename: C
authors.initials: C
authors.lastname: Doetkott
authors.forename: L K
authors.initials: LK
authors.lastname: Nolan
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D018441:Biofilms; D003470:Culture Media; D004197:Disease Reservoirs; D004783:Environmental Microbiology; D004926:Escherichia coli / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000378:metabolism / Q000635:transmission; D029968:Escherichia coli Proteins / Q000378:metabolism*; D005243:Feces / Q000382:microbiology; D010802:Phylogeny; D011200:Poultry / Q000382:microbiology*; D011201:Poultry Diseases / Q000382:microbiology / Q000635:transmission; D014774:Virulence
chemical_list: D003470:Culture Media; D029968:Escherichia coli Proteins