Communication in biofilms

BOB MCLEAN RM12 at swt.edu
Fri Jan 24 09:52:55 EST 1997

I would like to reply to the comments made by Denise Lindsay and others
regarding intracellular communication in biofilms.  The idea that starvation
pressures within a biofilm interior, induce cells at the surface to increase
nutrient production or nutrient transport is quite intriguing.  Has there been
any work published in this area?

There is presently a lot of speculation on the impact of quorum sensing
(autoinducer) genes that are regulated by population density.  While first
described in the luminescent bacterium, Vibrio fischeri, these genes are now
described in a number of other organisms.  The major genes in V. fischeri are
luxR and luxI which both regulate light production.  In Pseudomonas aeruginosa,
homologues for luxR and luxI, regulate virulence factors as shown by Barbara
Iglewski, Peter Greenberg and collaborators.  In the plant pathogen,
Agrobacterium tumefaciens, quorum sensing genes stimulate conjugation as shown
by Clay Fuqua and Steve Winans.  There is an excellent review by Fuqua, Winans,
and Greenberg (Annual Review of Microbiology 50: 727 - 751, 1996) which
summarizes current work on autoinducers.  As biofilms represent
surface-adherent communities with relatively high cell density, one would
expect luxR luxI homologues to play some role in intercellular signalling and
regulation.  There are at least two groups currently investigating the role(s)
of autoinducers in biofilms:  1) Pete Greenberg, Barb Iglewski, and Bill
Costerton, and 2) Clay Fuqua and myself (Bob McLean).

One word of caution:  While autoinducers may be significant contributors to
biofilm physiology and function, they are not likely to be the only regulators
in this environment.

R.J.C. (Bob) McLean
Dept. Biology
Southwest Texas State University
San Marcos, Tx 78666
(512)245-3365 phone
(512)245-8713 fax
Email:  RM12 at swt.edu

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