In vivoandin vitromodels of the human colonic flora

Abstract

The study of colonic flora composition and metabolism presents considerable methodological problems. Attempts to circumvent these problems have led to the development of numerous in vitro and in vivo models to simulate the human colon and its microbial population. In terms of in vivo models, conventional laboratory animals have many limitations. Data of greater relevance to man can be obtained by using germ-free rodents associated with human colonic bacteria. The applications of such animals to studies of toxicity of chemicals and gastrointestinal infections are discussed. The advantages and disadvantages of the various in vitro systems for studying gut microflora and its metabolic activity (from simple static cultures to the more sophisticated continuous and semicontinuous flow models) are reviewed. The apparatus involved is described together with practical information on media, running conditions, and sampling. The bacteriological and metabolic criteria for establishing the similarity of the models to the in situ colonic flora are also discussed. The final sections of the review are devoted to the major applications (current and future) of the models, including fermentation studies on dietary fiber, metabolism of nutrients and foreign compounds (including carcinogens) in food, and the investigation of colonization resistance.

Perspectives on the role of the human gut microbiota and its modulation by pro- and prebiotics

“…Gnotobiotic technology provides a useful tool for studying interactions between speci®c members of the human gut micro¯ora, such as the role played by speci®c bacteria in colonisation resistance to pathogens, bacterial virulence, metabolism of dietary constituents or xenobiotic compounds (Rumney & Rowland, 1992). Conventional animals may not provide information of direct relevance to the human gut ecosystem because of major differences in the composition of the microbiota between animals and humans.…”

“…Continuous or semi-continuous¯ow systems, on the other hand, replicate the ecological conditions of the human gut to a much greater degree. Continuous in¯ow of growth media, and out¯ow of biomass, enable a diverse micro¯ora to be maintained in a steady state (Rumney & Rowland, 1992). Models of the human gut of varying degrees of complexity have now been developed (Miller & Wolin, 1981;Allison et al 1989;Bearne et al 1990;Molly et al 1994;Minekus & Havenaar, 1996;.…”

“…To enable us to ask speci®c questions about the human gut micro¯ora, in vitro and in vivo models of the human gut have been developed (Gibson et al 1988;Rumney & Rowland, 1992;Conway, 1995).…”

Metabolism of Ginsenoside Rb1 by Human Intestinal Microflora and Cloning of Its Metabolizing β-<small>D</small>-Glucosidase from <i>Bifidobacterium longum</i> H-1

“…27,28) This is due to the affinity between the intestinal lumen of the individual and the bacteria. Newly ingested bacteria cannot necessarily colonize and proliferate in the intestine.…”

Human Colonic Microbiology and the Role of Dietary Intervention: Introduction to Prebiotics

“…A variety of model systems have been developed to investigate colonic fermentation of prebiotics (Rumney and Rowland, 1992;Conway, 1995;Rycroft et al, 1999). Screening usually starts by looking at the relative fermentability of prebiotics with in vitro static batch culture fermenters.…”