Previous Article | Next Article ![]()
Appl. Environ. Microbiol., Feb 1997, 734-742, Vol 63, No. 2
Y Shi, CL Odt and PJ Weimer
Three predominant ruminal cellulolytic bacteria (Fibrobacter succinogenes
S85, Ruminococcus flavefaciens FD-1, and Ruminococcus albus 7) were grown
in different binary combinations to determine the outcome of competition in
either cellulose-excess batch culture or in cellulose-limited continuous
culture. Relative populations of each species were estimated by using
signature membrane-associated fatty acids and/or 16S rRNA-targeted
oligonucleotide probes. Both F. succinogenes and R. flavefaciens coexisted
in cellulose-excess batch culture with similar population sizes (58 and
42%, respectively; standard error, 12%). By contrast, under cellulose
limitation R. flavefaciens predominated (> 96% of total cell mass) in
coculture with F. succinogenes, regardless of whether the two strains were
inoculated simultaneously or whether R. flavefaciens was inoculated into an
established culture of F. succinogenes. The predominance of R. flavefaciens
over F. succinogenes under cellulose limitation is in accord with the
former's more rapid adherence to cellulose and its higher affinity for
cellodextrin products of cellulose hydrolysis. In batch cocultures of F.
succinogenes and R. albus, the populations of the two species were similar.
However, under cellulose limitation, F. succinogenes was the predominant
strain (approximately 80% of cell mass) in cultures simultaneously
coinoculated with R. albus. The results from batch cocultures of R.
flavefaciens and R. albus were not consistent within or among trials: some
experiments yielded monocultures of R. albus (suggesting production of an
inhibitory agent by R. albus), while others contained substantial
populations of both species. Under cellulose limitation, R. flavefaciens
predominated over R. albus (85 and 15%, respectively), as would be expected
by the former's greater adherence to cellulose. The retention of R. albus
in the cellulose-limited coculture may result from a combination of its
ability to utilize glucose (which is not utilizable by R. flavefaciens),
its demonstrated ability to adapt under selective pressure in the chemostat
to utilization of lower concentrations of cellobiose, a major product of
cellulose hydrolysis, and its possible production of an inhibitory agent.
Copyright © 1997, American Society for Microbiology
Competition for cellulose among three predominant ruminal cellulolytic bacteria under substrate-excess and substrate-limited conditions
Department of Dairy Science, University of Wisconsin-Madison 53706, USA.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»