Dick,
You raise some very valid points here. A number of studies, some published
and the majority in progress, have illustrated that a number of genes
become activated upon microbial adhesion to surfaces. I would speculate
that additional genes become activated during the development and
maturation of biofilms. Certainly, quorum sensing has been shown to be an
important aspect of biofilms (Davies et al, Science 280: 295 - 298, 1998;
Batchelor et al, Appl. Environ. Microbiol. 63: 2281 - 2286, 1997; Givskov
et al, J. Bacteriol. 178: 6618 - 6622, 1996; and our own work FEMS
Microbiol. Lett. 154: 259 - 263 and Appl. Environ. Microbiol. 64: 3486 -
3490).
One note of caution:
While quorum sensing is important, it is not the only determinant of
biofilm physiology. George O'Toole and Roberto Kolter have shown that
twitching motility and over 20 other genes are important for microcolony
and biofilm formation (Mol. Microbiol. 30: 295 - 304, 1998, Mol. Microbiol.
28: 449 - 461, 1998). A number of other investigators are also looking at
genes involved in biofilm formation, structural development, physiology,
antibiotic resistance, etc.
The Center for Biofilm Engineering at Montana State University (web site:
http://www.erc.montana.edu) is organizing Biofilms 2000, a followup
conference to the highly successful Snowbird meeting. One idea that was
raised by Rob Palmer was to address this definition issue at a round table
session at this meeting. I would really encourage everyone to attend.
Bob McLean
At 07:07 PM 7/26/99 -0500, you wrote:
>I think a critical aspect of a biofilm is not only the structural one
>but also that there is a change in phenotype, that is, the cells
>do something differently because of the environment created by the
>other cells in the film. The term 'quorum sensing' is used to
>describe this.
>Should the presense of quorum sensing be part of the definition of
>a biofilm or is the adherence to a set of structural qualifications
>sufficient?
>Dick Murphy
>
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___________________________________________________________________________
R.J.C. (Bob) McLean, Ph.D.
Dept. Biology
Southwest Texas State University
601 University Drive
San Marcos, Tx 78666
USA
(512)245-3365 phone
(512)245-8713 FAX
Email: RM12 at swt.eduhttp://www.bio.swt.edu/micro/mclean/mclean.html
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