Nice to see people using the biofilm newsgroup!
Of course definitions of biofilm are extremely difficult because the
structures vary so enormously. We have just published a paper (FEMS
Microbiology Ecology 22 , 1997, 1-16) discussing the structure of
biofilm where we suggest that some of the differences in structure, at
least can be explained as due to huge differences in substrate
concentration. Possibly up to a million fold between a squishy dental
plaque of someone eating a Mars bar and the structures one sees in pure
water systems. Hoping to put the paper onto the internet if anyone is
No my definition has always been a little imprecise, but this is what I
wrote in Bacterial Biofilms (1994) p 1 etc.
A biofilm is:
*A predominantly two-dimensional microbial community which forms at a
solid/liquid interface and which may become spatially heterogeneous by
virtue of physico-chemical gradients that develop within it.*
I can't say its perfect and it could be altered. For example other
interfaces are possibilities. Communities of this sort form at
gas/liquid interfaces if there is sufficient water in the atmosphere.
Also interfacial communities form at liquid/liquid interfaces. For
example at the oil water interface in oil storage tanks.
Spatial heterogeneity may seem a bit of an add-on but I think
communities really do have some heterogeneity of this form if they are
Over to you all.....