POSTERS - BLAST X - University of Utah
POSTERS - BLAST X - University of Utah
POSTERS - BLAST X - University of Utah
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<strong>BLAST</strong> X Poster #72<br />
A MECHANICAL AND GENETIC STUDY OF ESCHERICHIA COLI SWARMING MOTILITY<br />
Matthew Copeland and Douglas B. Weibel<br />
Department <strong>of</strong> Biochemistry, <strong>University</strong> <strong>of</strong> Wisconsin-Madison, WI 53706 USA<br />
Bacterial swarming is a phenotype associated with the motility <strong>of</strong> bacteria across<br />
surfaces in search <strong>of</strong> resources. In this abstract we describe two approaches to understand this<br />
phenotype in Escherichia coli; a ‘mechanistic’ approach to elucidate potential flagella/flagella<br />
interactions between adjacent swarming cells and a genetic investigation to chart the<br />
expression <strong>of</strong> genes unique to the swarming phenotype.<br />
In contrast to swimming motility, swarming bacteria cells migrate cooperatively across<br />
surfaces. The role <strong>of</strong> physical interactions in the coordination <strong>of</strong> swarming motility is unknown. It<br />
has been shown that swarming bacteria align along their long axis and move as multicellular<br />
rafts from which the characteristic dynamic swirling patterns <strong>of</strong> swarming emerge. The<br />
alignment <strong>of</strong> cells may facilitate or accompany the intercellular bundling <strong>of</strong> flagella between<br />
adjacent cells and play a role in the characteristic, coordinated movement observed during<br />
swarming motility. To test this hypothesis, we have created strains <strong>of</strong> E. coli with fluorescent<br />
flagella and are using space- and time-resolved fluorescence resonance energy transfer (FRET)<br />
to measure flagella/flagella interactions.<br />
Iron starvation is known to signal swarmer cell differentiation in Vibrio parahaemolyticus<br />
and the genes for iron uptake and metabolism have been shown to be elevated in swarming<br />
populations <strong>of</strong> Salmonella typhimurium. We have found that iron metabolism and iron<br />
acquisition genes are upregulated in swarming cells <strong>of</strong> E. coli versus planktonic cells. A specific<br />
role for iron in E. coli swarming cells is unknown. Like V. parahaemolyticus, iron starvation may<br />
be a signal for swarmer cell differentiation in E. coli or swarming development and motility may<br />
require intracellular levels <strong>of</strong> iron in excess <strong>of</strong> those necessary for growth under vegetative<br />
conditions. We are exploring the role <strong>of</strong> iron in E. coli swarming using a combination <strong>of</strong> chemical<br />
and gene expression techniques and strains containing iron metabolism gene knockouts.<br />
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