Agriculture Reference
In-Depth Information
Bacteria
Bacteria are the tiniest members of the soil food web. They are single-celled organisms
— they each have just one cell. There are hundreds of millions of them in a gram of
healthy compost, even a billion. Pick up a handful of good compost and you have more
bacteria in your hand than there are people in the world.
How is it possible that anything is that small? I can't even fathom it, just like I can't un-
derstand how there are at least 100 trillion stars in one galaxy and 100 trillion galaxies in
the universe. The astronomers have lost me here, and the biologists have lost me when I try
to imagine the tens or hundreds of billions of bacteria in and on my body, 10 times as many
as there are cells that make up my body.
Bacteria consume minerals by taking them in right through their cell wall. They can
swap DNA and other body parts with each other, so a colony can learn extremely quickly.
This could be the basis for a good horror movie. Actually, it's a real phenomenon that not
only bacteria, but insects and weeds are becoming more and more resistant to our antibiot-
ics and pesticides.
Bacteria occupy the majority of the leaf and root surfaces of a plant. They break down
simple substances and toxins and aggregate the basic building blocks of the soil. Some
common bacteria are Lactobacillus, Rhizobia and Pseudomonas. Bacteria are dominant in
aquatic systems and the soil of grasslands, whereas fungi become more dominant in the soil
of shrublands and forests.
There is another single-celled group called archaea that I lump in with bacteria, but don't
tell any microbiologists that because they probably wouldn't be happy with me. Apparently
archaea mostly look kind of similar to bacteria, but have genes that are more similar to
plants and animals than bacteria. There are many more differences that have caused some
biologists to classify them in their own kingdom. For our purposes, bacteria and archaea
are classified together because their cells don't have a nucleus, whereas everyone else's do
— fungi, protists, animals and plants.
