Meanwhile, Suau et al. [3] examined bacteria from the
opposite end of the gastrointestinal tract. The microbial
flora of the intestinal tract has always attracted considerable
attention because of its important role in human health.
The colon is functionally an anaerobic fermentation
chamber packed with bacteria, with cell densities approaching
1012 per gram in feces. The resident flora provides some
useful functions to its human host, including the synthesis
of certain vitamins, and inhibition of intestinal colonization
by pathogenic intruders. Suau et al. [3] found that only
about 30% of the microscopically observable cells in the
fecal sample went on to form colonies on agar plates under
optimal anaerobic conditions. Although they did not identify
the cultivated species in their sample, previous work by
Moore and Holdeman [11] using standard phenotypic
methods found over 100 bacterial species in cultures from
20 people, with up to 30 cultured species per individual.