Competition for cellobiose among three predominant ruminal cellulolytic bacteria under substrate-excess and substrate-limited conditions.
The ruminal cellulolytic bacteria Ruminococcus flavefaciens FD-1 and Fibrobacter succinogenes S85 coexisted in substrate-excess coculture with about equal population size, but R. flavefaciens outcompeted F. succinogenes for cellobiose in the substrate-limited cocultures whether the two strains were coinoculated or a steady-state culture of F. succinogenes was challenged by R. flavefaciens. This outcome of competition between these two strains is due to a classical pure and simple competition mechanism based on affinity for cellobiose. Although the population size of F. succinogenes was much higher (> 70%) than that of another cellulolytic species, Ruminococcus albus 7 in substrate-excess coculture, F. succinogenes was replaced by a population of R. albus in the substrate-limited coculture in both coinoculation and challenge experiments. R albus outcompeted F. succinogenes, apparently due to selection in the chemostat of a population of R. albus with a higher affinity for cellobiose. R. albus also outcompeted R. flavefaciens under substrate-limited conditions.
Shi
Y
Y
Department of Dairy Science, University of Wisconsin-Madison 53706, USA.
Weimer
P J
PJ
D000818:Animals; D001439:Bacteroides / Q000378:metabolism*; D002475:Cellobiose / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism; D003470:Culture Media; D006094:Gram-Positive Bacteria / Q000378:metabolism*; D008828:Microbiological Techniques / Q000295:instrumentation; D012417:Rumen / Q000382:microbiology*
D003470:Culture Media; D002475:Cellobiose; D002482:Cellulose