In Vitro Models of the Mammalian Caecum and Colon

Abstract

The indigenous microflora of the mammalian gastrointestinal tract influences significantly the anatomical, physiological and immunological characteristics of its host (1,2). It is important therefore to understand the ecological mechanisms governing interactions between the bacteria and host and amongst the bacteria themselves and also to study the contribution of the gut flora to the metabolism of ingested compounds and host secretions. The relationships between a few gut organisms has been studied in vitro (3) and by specifically colonizing germ-free rodents (4), but the interspecific mechanisms observed in such simple systems may not be relevant to the more complex environment of the gut. The study of the ecology of the microflora and its metabolic activity in vitro is complicated by the difficulties of cultivating the flora as a complex mixed culture. The conventional cultural techniques, which employ batch or ‘closed’ cultures, remove most of the biotic and abiotic constraints in the in-vivo ecosystem. This can result in a distortion of the proportions of the components of the flora, so that metabolism and ecological interactions in such cultures may not be representative of those found in the gut.