Project description:Rumen bacterial species belonging to the genera Butyrivibrio are important degraders of plant polysaccharides, particularly hemicelluloses (arabinoxylans) and pectin. Currently, four distinct species are recognized which have very similar substrate utilization profiles, but little is known about how these microorganisms are able to co-exist in the rumen. To investigate this question, Butyrivibrio hungatei MB2003 and Butyrivibrio proteoclasticus B316T were grown alone or in co-culture on the insoluble substrates, xylan or pectin, and their growth, release of sugars, fermentation end products and transcriptomes were examined. In single cultures, B316T was able to degrade and grow well on xylan and pectin, while MB2003 was unable to utilize either of these insoluble substrates to support significant growth. Co-cultures of B316T grown with MB2003 revealed that MB2003 showed almost equivalent growth to B316T when either xylan or pectin were supplied as substrates. The effect of co-culture on the transcriptomes of B316T and MB2003 was very marked; B316T transcription was largely unaffected by the presence MB2003, but MB2003 expressed a wide range of genes encoding carbohydrate degradation/metabolism and oligosaccharide transport/assimilation in order to compete with B316T for the released sugars. These results suggest that B316T has a role as an initiator of the primary solubilization of xylan and pectin, while MB2003 competes effectively as a scavenger for the released soluble sugars to enable its growth and maintenance in the rumen.
Project description:Expression data for Desulfovibrio alaskensis strain G20 grown on lactate in sulfate-limited monoculture and syntrophic coculture with Methanococcus maripaludis or Methanospirillum hungatei in chemostats at a low growth rate of 0.027h-1. 7 samples of Desulfovibrio alaskensis strain G20 grown in syntrophic coculture on lactate with either Methanococcus maripaludis (4 replicates) or Methanospirillum hungatei (3 replicates), and 5 samples of sulfate-limited monoculture growth of strain G20 on lactate.
