Life, Life Everywhere

Life, Life Everywhere

Life in its most basic state is the bacterium. Bacteria are among the oldest,

simplest, and most common forms of life on the planet. Currently scientists can

separate and identify over 2,500 different kinds, but thousands more doubtless

remain to be discovered, described, and classified. Sizewise, individual

bacteria are the tiniest of free—living cells, so small that one drop of water

may contain as many as a million individual bacteria. And they still have enough

space to move about quite freely. Imagine, for example, that a single bacterium

were seated in the middle of the period at the end of this sentence. To the

lonely bacterium perched in its center, the period would appear the size of an

average football stadium. Generally speaking, though, bacteria do not spend much

time by themselves. They are social creatures that live in large groups and seem

to make up for their diminutive size by a birth rate that is almost impossible

to comprehend.

Imagine that the solitary bacterium sitting alone in the middle of the period is

adopted as a pet. Its owners treat it well, give it all the food it can eat and

all the space it will need, and keep all dangerous bacteria—killers away. Living

in a bacterial Garden of Eden, free to be fruitful and multiply without limit,

it shares its idyllic garden with all of its offspring. In just three days, this

single bacterium—by way of cell division approximately every 20 minutes—will

give rise to an extended actively reproducing bacterial family that takes up

more space than does the planet earth. In those three days it will have created

its own planet larger than Earth, composed entirely of bacteria. Fortunately,

life is full of hazards for bacteria, and untold hordes of plants and animals

consume them by the millions.

Being one of the earth's oldest inhabitants, reproducing in the simplest way (by

fission, in which a cell grows until it breaks in half, creating two

individuals), bacteria have evolved into many forms and have adapted to highly

varied environments. This simply means that bacteria are virtually everywhere.

The bacteria that perform a useful function, such as those that aid digestion by

breaking down food, are joined by the harmless stowaways that live on and within

the human body. The most notorious of all microorganisms are those formidable

adversaries capable of causing severe, even deadly, diseases.

The human mouth is a rich breeding ground teeming with many types of bacteria.

On the tongue alone several hundred different species of bacteria grow side by

side. Tooth decay, caused by a waste product of bacterial digestion, is a sample

of bacterial handiwork.

Generally humans don't tend to give much thought to bacteria, since they can't

be seen, heard, smelled, tasted, or felt. One can suddenly be reminded of them

by pus—filled infections, decaying vegetables, smelly socks, or things equally

repugnant. Although such signs of bacterial activity result in rather negative

feelings about them, bacteria are the life—form on which the vast majority of

all other living things depend.

For more than two billion years, bacteria probably shared the primeval planet

with no life—form other than blue—green algae. During this time, the Precambrian

Eras, neither the atmosphere nor the soil of the planet was capable of

supporting complex life—forms. By the end of that period, about 600 million

years ago, and largely as a result of the ceaseless work of the bacteria, the

biosphere of the planet was ready to play host to a mind—boggling diversity of

life. Eventually that led to relatively complex life—forms such as humans.

Among microscopic organisms, bacteria's most efficient competitor for living

space is the fungus. As far as scientists can determine, fungi have inhabited

the earth since early Paleozoic times, about 400 million years ago. By that time

bacteria had already had a head start of over a billion and a half years. Being

a lot smaller, bacteria are considered much more abundant, but fungi are also

typically everywhere. A wheelbarrow full of soil, for example, contains more

fungi than there are people on the earth. (That many bacteria could be found

swimming in a mere 5,000 drops of water—less than 2⁄3 cup.)

Throughout the eons of their existence, fungi have been one of bacteria's most

competent natural prey organisms. One fungus, for example, releases a powerful

chemical quite deadly to certain bacteria. Fungi that have developed this type

of defense have become allies to humans in the war against infection and

disease.

In 1928, an English scientist named Alexander Fleming was growing a dish of

bacteria in a London laboratory. He noticed it had been contaminated by a rogue

bit of fungus that had somehow managed to kill off all the bacteria surrounding

it. As he observed it, the action of the fungus became even more interesting. In

the long run Fleming found that the fungus was giving off some kind of liquid

that was very definitely a “bacteria killer.”

This newly discovered chemical substance, subsequently defined and reproduced in

the laboratory, came from the penicillin family. Fleming named the liquid

“penicillin.” This single substance changed the course of treatment of

infectious diseases and has saved more human lives than any other drug in the

history of medicine. Although an English scientist discovered it, and in the

11th century the Mayan people recognized the therapeutic qualities of the mold

that grew on tortillas, penicillin was actually “invented” millions of years ago

by an anonymous mutant fungus.

Since Fleming's discovery numerous other antibiotics, such as amoxicillin,

erythromycin, streptomycin, and tetracycline, have been discovered in much the

same way—as naturally occurring fungal and bacterial products. Medical

researchers believe that they have scarcely scratched the surface of the

antibiotic heap. Considering that the vast majority of bacterial and fungal

types are as yet undiscovered, cures to other ailments probably have already

been created by some unknown fungi. They are just waiting to be discovered,

possibly by the reader!