The gut flora are the
microorganisms that normally live in the
digestive tract and can perform a number of useful functions for their hosts.The average human body, consisting of about 1013
cells, has about ten times that number of microorganisms in the gut.
Bacteria make up most of the flora in the
colon and 60% of the mass of
feces. Somewhere between 300 and 1000 different
species live in the gut, with most estimates at about 500. However, it is probable that 99% of the bacteria come from about 30 or 40 species.
Fungi and
protozoa also make up a part of the gut flora, but little is known about their activities.
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