It is interesting to see the numerous ways in which it has
been suggested that biofilms can be defined. I agree with
Kieth Cooksey's point that bioFILM does connote a layer or
surface coating. However, in the early stages of biofilm
development, or in low nutrinet conditions the single cells
or clumps of microorganisms that are associated with a
surface may not form a film per-se. Yet thinking about a
thin film at a surface is useful for thinking about
"biofilm" processes from an engineering perspective. In
many ways it is scale dependant. As we look at bioilms with
ever increasing magnification the structural
heterogenaities become more apparent. Since the term
biofilm was coined (does anybody know when it was first
applied?) we have come a long way in our kowledge. As has
been said previously in this discussion, biofilms may be
both temporally and spatially complex and in many cases
really not like films at all. I have been thinking about
colonies growing on an agar plate - groups of cells
associated with a surface. Would we say that an agar plate
has A biofilm, or if there were X CFU would we say the
plate has X biofilms. For a developing biofilm in which
only a few (how many is a few?) cells are on a surface we
are probrably OK refering to it as a nascent biofilm. But
what about when there are a few cell clusters, say 1
cluster per cm2 in a mature "biofilm" growing in an
oligotrophic environment? I guess there is no collective
noun for a group of microcolonies other than biofilm.
Personally I think that the term "biofilm" with qualifying
adjectives can be used to describe all of these situations
even though, like many words, the term in its original
context may be now slightly dated.
----------------------
paul stoodley
University of Exeter
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