Submitted to: Conference on Gastrointestinal Function
Publication Type: Abstract Only
Publication Acceptance Date: 3/12/2003
Publication Date: 3/12/2003
Citation: LAWSON, P.A., WHITEHEAD, T.R., COTTA, M.A., COLLINS, M.D. MOLECULAR TAXONOMY: REVEALING UNSEEN DIVERSITY WITH THE GI TRACT. 25TH CONFERENCE ON GASTROINTESTINAL FUNCTION. 2003. ABSTRACT P. 28. Interpretive Summary:
Technical Abstract: The intestinal tract of both man and animals harbors an enormous diversity of microorganisms that play a decisive role in the health and physiology of the host. However, the microbial ecology of these ecosystems is not well understood due to the inadequacy of classical, culture-dependent microbiological methods. The vast majority of organisms within the gut flora consist of obligate bacterial anaerobes most of which can be assigned to three major phylogenetic lineages viz: Bacteroides group, Clostridium coccoides group, and Clostridium leptum subgroup. Molecular taxonomic inventories obtained directly from human and animal feces have shown that the vast majority (60-80%) of generated rDNA sequences do not correspond to known organisms and clearly derive from hitherto unknown species within the gastrointestinal tract. However, it is not known if this "hidden" flora are non-culturable or if they represent organisms which have so far eluded identification using traditional phenotypic taxonomic methods. The application of improved diagnostic tools, in particular the combined use of phenotypic approaches such as miniaturized biochemical testing and protein profiling and molecular based methodologies such as 16S rDNA gene sequencing, has facilitated a plethora of organisms belonging to completely unknown genera being scientifically described. Until the majority of organisms present in the GI tract have been described, the complex interrelationships between both the bacterial flora themselves and in addition, with the host, cannot be fully understood. Non-culture based methodologies have given us an invaluable insight into the enormous diversity present within this environment yet to be elucidated. However, it is only by recovering organisms in pure culture and subjecting them to the appropriate analyses that questions of how the intestinal bacterial community responds to perturbations such as different diets and the use of antibiotics, probiotics, etc., can be addressed.