Biofilms are complex mixtures of adhesive, organized cells that comprise the
natural state for many bacteria that help them colonize a host or foul equipment.


Many E. coli genes have found to be required for biofilm competence using laboratory
monocultures designed to induce biofilm formation.
If a mutant fails to form normal biofilms, that gene is assumed ot be involved, either directly or indirectly, in biofilm formation.

Microarrays have also been useful in identifying genes esential for biofilm formation
whose expression changes significantly during biofilm formation.