Bob : I agree that quorum sensing isn't everything that is going on. Back
in 1986 Bob Murray and I showed that heterotrophic bacterial growth in a
mixed species biofilm in oligotrophic media was light dependent. We
measured H3-Thy incorporation into bacteria as a function of the presence
of diatoms in the biofilm and the level of illumination. Funnily enough
after 13 years we have just experienced another peak in reprint requests!
Shows someone is searching the literature I suppose and that this is
becoming a new area of interest. My colleague here has just been funded to
examine the molecular biology of this system.
KE Cooksey,Research Prof, MSU BZN
At 09:27 AM 7/27/1999 -0500, you wrote:
>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
> >
>___________________________________________________________________________
>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.edu
>http://www.bio.swt.edu/micro/mclean/mclean.html
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