Effect of oxygen and growth medium on in vitro biofilm formation by Escherichia coli

ABSTRACTThe effects of oxygen availability on in vitro biofilm formation by an Escherichia coli K-12 strain and 13 clinical E. coli strains were compared. All E. coli strains were capable of forming monospecies biofilm on polystyrene in aerobic media. The K-12 strain produced biofilm in both aerobic glucose minimal medium (ABTG), and aerobic trypticase soy broth (TSB) whereas the majority of the clinical strains produced significant biofilm only in aerobic TSB (9 of 13). In anaerobic media, E. coli K-12 and 9 of the 13 clinical strains were capable of forming biofilm in vitro. Only three clinical strains formed biofilm in anaerobic TSB whereas six clinical strains produced detectable biofilm in anaerobic ABTG. None of the strains tested were capable of forming biofilm in both anaerobic ABTG and anaerobic TSB. Strains that were good biofilm formers in aerobic ABTG also produced the highest amount of biofilm in anaerobic ABTG (R2 = 0.90). Image analysis revealed notable differences in...