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K.E.Cooksey umbkc at gemini.oscs.montana.edu
Fri Jul 23 03:32:02 EST 1999

>Date: Wed, 21 Jul 1999 09:29:45 -0600 
>To: "Robert J. Palmer Jr." <rjpalmer at utkux.utcc.utk.edu> 
>From: "K.E.Cooksey" <umbkc at gemini.oscs.montana.edu> 
>Subject: Re: Definition of a biofilm 
>In-Reply-To: <l03110701b3bb66c0b620@[]> 
>References: < at gemini.oscs.montana.edu> 
>Rob ; I see your point. One organism is not a biofilm[ look up the meaning 
of film!], two are a film, albeit a small one , but I think we are entering 
the " angels on a pin" realm here. I agree that biofilms are not black 
boxes that can be modeleled easily. I fought contantly with Bill Characklis 
at coffee many mornings about such. Other examples of academic arguements 
might include what are the diffrences between biochemistry, biological 
chemistry and molecular biology? Debates have raged there too. It's all a 
matter of perspective. I also remember working in Berkeley with Roger 
Stanier : He believed that there were about 5 Pseudomonads sp.- now because 
of 16S technology we have dozens. It all depends whether one is a lumper or 
a splitter. The same can be said of the biofilm debate. 
>At 08:15 AM 7/21/1999 -0400, you wrote: 
>>I don't think anyone is reinventing the wheel here. Bob brought up some 
>>points that are frequently raised WITHIN the biofilm community, and as such 
>>are even more pertinent to those entering a burgeoning field. 
>>For example, does a single cell qualify as a biofilm by your definition? 
>>I would suggest not, but only by virtue of the wording that requires 
>>"accumulation". However a single cell can be immobilized and can produce 
>>extracellular material. Let's say it divides. Do those two cells now 
>>constitute a biofilm as an "accumulation"? They certainly fit all the 
>>other requirements of either of your definitions. The Characklis-edited 
>>magnum opus (to which many individuals made very important contributions) 
>>is still the Bible of biofilm research despite its heavy emphasis on 
>>engineering aspects and desptite our recognition that biofilms are NOT 
>>black boxes whose physical (and physiological) characteristertics can be 
>>modeled like a bomb blast. 
>>I too am a bit bothered by all this worry about what constitutes a biofilm 
>>- it has been and always will be an operating definition subject to 
>>interpretation and "waffle". Discussion certainly does a minimal amount of 
>>damage, and open discussion in this (and other) forums helps clarify to 
>>which camps we all belong. 
>>Rob Palmer 
>>>I don't want to sound as though I am older than I am, but why do we need 
>>>another definition of a biofilm? Perhaps the first review of biofilm 
>>>engineering and biology was published 16 years ago by the late Bill 
>>>Characklis and I. In it we defined a biofilm in the following way : 
>>>....immobilized cells grow, reproduce, and produce extracellular polmer 
>>>substances that frequently extend from the cell, forming a tangled mass of 
>>>fibers lending structure to the entire assemblage which shall be termed a 
>>>biofilm. The term biofilm does not necessarily imply a surface accumulation 
>>>that is uniform in time and/or space. 
>>>We dveloped this into a shorter version that defines a biofilm as "the 
>>>accumulation of microbial cells , their products and inorganic particles at 
>>>a wetted surface ".[ to take into the account that natural biofilms 
>>>accumulate lots of silt]. 
>>>Let's not re-invent the wheel! 
>>>Keith Cooksey, Research Professor 
>>>As part of the final part of the review we mentioned 13 areas that we felt 
>>>were in need of further work. It is interesting to see how many of these 
>>>STILL need further work! 
>>>The reference is Adv in Appl. Microbiol. 29 93-137 [1983] 

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