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Applied and Environmental Microbiology, August 2000, p. 3574-3585, Vol. 66, No. 8
Department of
Microbiology,1 and Center for Biofilm
Engineering,2 Montana State University,
Bozeman, Montana 59717, and School of Biological Sciences, The
Flinders University of South Australia, Adelaide, South Australia
5001, Australia3
Received 30 December 1999/Accepted 4 May 2000
Growth of the chitin-degrading marine bacterium S91 on solid
surfaces under oligotrophic conditions was accompanied by the displacement of a large fraction of the surface-derived bacterial production into the flowing bulk aqueous phase, irrespective
of the value of the surface as a nutrient source. Over a 200-h period of surface colonization, 97 and 75% of the bacterial biomass generated on biodegradable chitin and a nonnutritional silicon surface, respectively, detached to become part of the free-living population in
the bulk aqueous phase. Specific surface-associated growth rates that
included the cells that subsequently detached from the substrata varied
depending on the nutritional value of the substratum and during the
period of surface colonization. Specific growth rates of 3.79 and
2.83 day
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Spatial and Temporal Variations in Chitinolytic Gene Expression
and Bacterial Biomass Production during Chitin Degradation
1 were obtained when cells first began to
proliferate on a pure chitin film and a silicon surface, respectively.
Later, when cell densities on the surface and detached cells as CFU in
the bulk aqueous phase achieved a quasi-steady state, specific growth
rates decreased to 1.08 and 0.79 day
1 on the chitin and
silicon surfaces, respectively. Virtually all of the cells that
detached from either the chitin or the silicon surfaces and the
majority of cells associated with the chitin surface over the 200-h
period of surface colonization displayed no detectable expression of
the chitin-degrading genes chiA and chiB. Cells
displaying high levels of chiA-chiB expression were detected only on the chitin surface and then only clustered in discrete
areas of the surface. Surface-associated, differential gene expression
and displacement of bacterial production from surfaces represent
adaptations at the population level that promote efficient utilization
of limited resources and dispersal of progeny to maximize access to new
sources of energy and maintenance of the population.
*
Corresponding author. Mailing address: Center for
Biofilm Engineering, 366 EPS Building, Montana State University,
Bozeman, MT 59717. Phone: (406) 994-3820. Fax: (406) 994-1855. E-mail: gill_g{at}erc.montana.edu.
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