Synergism in biofilm formation between Salmonella enteritidis and a nitrogen-fixing strain of Klebsiella pneumoniae

A laboratory reactor, which simulates biofilm formation in water pipes, was used to study interactions in biofilm formation between a nitrogen-fixing strain of Klebsiella pneumoniae and Salmonella enteritidis. The level of attachment of Salm. enteritidis was higher in the binary biofilm than in the single species biofilm. In the initial colonization phase the binary biofilm contained a much higher proportion of metabolically active cells than in single species biofilms formed by either Salm. enteritidis or Kl. pneumoniae. When a pulse of Salm. enteritidis was passed over an already established biofilm of Kl. pneumoniae it rapidly became integrated into the biofilm, from where it was subsequently released into the water column, along with Kl. pneumoniae. Klebsiella pneumoniae fixed nitrogen in the presence of Salm. enteritidis in both types of biofilm.