ABSTRACT
The human intestinal microbiota has never been so intensively studied as in this current
period. Over the last decade, the use of molecular methods, especially those based on 16S
ribosomal RNA, have generated much knowledge on the composition of the intestinal
microbiota of especially humans but also animals. The relatively easy accessible fecal
sample is the main source of intestinal microbiota used for various analyses. It is uncertain
how well fecal samples reflect the composition of the microbiota in the proximal parts of
the colon (1,2) but it is certainly very different from the small intestine. In order to study
the microbial composition and activity in these sites, one would need in vivo samples from
a large number of healthy individuals. Invasive sampling from healthy people is ethically
not acceptable. Animal models can be used for invasive sampling (see chapter by
Henriksson); however, due to physiological and anatomical differences, animals will have
a different microbiota. Therefore, in vitro techniques complement animal studies and offer
means to test specific hypotheses in a controlled, replicable manner without using animal
models or clinical samplings. With in vitro models, it is possible to simulate the conditions
in the human oral cavity, stomach, duodenum, jejunum, ileum, and in the ascending,
transverse, and descending sections of the colon.
