Biofilms

JOURNAL OF BACTERIOLOGY, Nov. 2007, p. 7948–7960
0021-9193/07/$08.00 0 doi:10.1128/JB.00787-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Vol. 189, No. 22

MEETING REVIEW
Biofilms 2007: Broadened Horizons and New Emphases
Robert J. Palmer, Jr.,1* and Paul Stoodley2
Oral Biofilm Communication Unit, Oral Infections and Immunity Branch, National Institute ofDental and Craniofacial Research,
National Institutes of Health, Bethesda, Maryland 20892,1 and Center for Genomic Sciences, 320 E. North Avenue,
Allegheny-Singer Research Institute, Pittsburgh, Pennsylvania 150902

KEYNOTE TALK 1
E. Peter Greenberg (University of Washington) opened the
meeting by speaking on the sociomicrobiology of biofilms: the
application to biofilm microbiology of E. O.Wilson’s insect
society-derived sociobiological concepts. In biofilms, bacteria
live in close proximity, the populations are heterogeneous in
activity, and individuals exhibit distinct behaviors, all of which
can be studied from an ethological perspective. Biofilms offer
a unique opportunity to examine the influence of environmental manipulation on gene expression and heritability (45).Greenberg focused on the role of iron in biofilm formation.
Iron is frequently a limiting nutrient in the human body as well
as in the natural environment, and motility and biofilm initiation in Pseudomonas aeruginosa are dependent on iron (4). The
human immune effector lactoferrin sequesters iron; in the
presence of lactoferrin (i.e., at low levels of available iron), P.
aeruginosa maintainstwitching motility, refuses to become
sessile, and is thus dramatically attenuated in biofilm formation (58). Production of lactoferrin is seen as a way for the host
immune system to slow the rate of biofilm formation so that
the microbial intruders can be dealt with before reaching a
clinically relevant population density. Greenberg continued
this theme by showing that the iron chelator EDTA candisperse a P. aeruginosa biofilm (3), and that citrate as a carbon
source can result in a flat biofilm because of citrate’s iron
chelation capability. Lastly he introduced the use of the iron

* Corresponding author. Mailing address: Oral Biofilm Communication Unit, Oral Infections and Immunity Branch, National Institute
of Dental and Craniofacial Research, National Institutes of Health,
Bldg.30, Room 310, 30 Convent Drive, Bethesda MD 20892. Phone:
(301) 594-0025. Fax: (301) 402-0396. E-mail: rjpalmer@mail.nih.gov.
Published ahead of print on 31 August 2007.
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therefore become more sophisticated and employ environmentally relevant substrata and media; accordingly, in vivo sampling and experimentation are becoming more common.Last,
moving to the fore is the recognition that the vast majority of
bacteria, including many of those involved in human disease,
must associate with other genera of bacteria as part of their
daily existence: multispecies communities are becoming a targeted research area.
This review summarizes the individual sessions through their
platform talks, many of which highlighted work presentedin
greater detail as poster presentations. We hope these descriptions (and the accompanying references, which give a flavor of
the topics) will convey the overall high scientific quality not
only of the invited talks but also of the talks selected from
submitted abstracts. The consensus of the attendees was that
this meeting elevated the already high reputation of this conference series. Wehope this review will convey some of that
feeling to those who have yet to attend the conference.

The 4th ASM Conference on Biofilms (Quebec City, Quebec, Canada, 25 to 29 March 2007) maintained the format so
valued at past conferences (keynote talks, invited speakers,
talks selected from abstracts, evening specialty sessions, and a
hands-on workshop) while increasing scientific diversity by...