Poster Presentations

Session Title: The Animal Microbiome
Presentation Date: Monday, August 18, 2008
Poster Board Number: 0397

MICROARRAY ANALYSIS OF A RUMINAL XYLANOYTIC BACTERIUM AND A METHANOGEN GROWN IN CO-CULTURE

C.J. Yeoman¹, W.J. Kelly², J. Rakonjac¹, Z. Kong², G.T. Attwood^2
1Massey University, Institute of Molecular Biosciences, Palmerston North, New Zealand, ²AgResearch Limited, Food and Textiles, Palmerston North, New Zealand

The xylan-degrading, rumen inhabiting eubacterium Butyrivibrio proteoclasticus has a unique genomic architecture consisting of two chromosomes of 3.5Mb and 300Kb and two cryptic megaplasmids of 360kb and 186kb. Due to the biologically-rich nature of the rumen it is likely B. proteoclasticus interacts with a diverse range of organisms. One interaction that can be observed microscopically is that with the ruminal methanogenic archaeon, Methanobrevibacter ruminantium. Using a specially constructed microarray containing the genomes of both B. proteoclasticus and M. ruminantium, the gene expression levels of the organisms grown in co-culture were compared to those of each grown in monoculture. Three major classes of gene were upregulated in the co-culture condition. These are predicted to encode proteins of novel or unknown function (hypothetical or conserved hypothetical), as well as proteins involved in exopolysaccharide and flagellar biosynthesis. The smallest megaplasmid, designated pCY185, makes the largest contribution, proportionally, to this interaction with almost 4.5% of its assigned open reading frames (ORFs) upregulated >3 fold. Conversely, despite the upregulation of three apparent operons, the largest megaplasmid contributes most of the ORFs that are downregulated >3 fold by this interaction.