Page 76 - The Microworld Miracle

Bacteria in Beneficial Symbiotic
Relationships With Other Living Things

By entering the bodies of a great many living things, including
human beings, bacteria provide direct or indirect advantages for
life. They even serve a purpose in the digestive systems of termites,
some of the smallest insects that can be seen with the naked eye.
Termites cannot digest cellulose on their own. They need bacteria to
help them in this process, and there are some 2.7 million bacteria in
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the stomach of a single termite. In the same way, bacteria also per-
mit ruminants—cows and other four-footed ungulates—whose me-
tabolisms are also unable to digest cellulose, to do so successfully.
Bacteria live everywhere in the healthy human body.
According to various estimates, there are some 10 million bacteria
on every square centimeter of human skin. For example, we know
that 80 different species live on the tongue alone, and that the num-
ber of bacteria expelled from human body ranges between 100 bil-
lion and 100 trillion. Some 10 billion organisms live on a square cen-
timeter of the human intestine. 42

Professor of microbiology Mark Pallen, of Queen's University
in Belfast, says this about the bacteria in the healthy human body:
There are some 80 different species in the mouth alone. Research
performed at the Jouy-en-Josas Ecology and Physiology Laboratory
THE MICROWORLD MIRACLE cies of microorganisms in the body. Their total numbers are in the
in France revealed 80 kinds of bacteria in the intestines. It is difficult
to give an exact figure for the micro-organisms living in the body,
but we may say that some 200 kinds are involved in keeping the
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body healthy.
This number of 200 that Mark Pallen cites is the number of spe-

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