Bacteria - Man's best friends
When we think of bacteria we usually think of something harmful that makes us sick.
This is wrong. Most bacteria are not harmful and many bacteria are beneficial. We cannot live without them. There are the bacteria around us and inside us. These are the good bacteria.
Bacteria are among the oldest living things on the Earth. Bacteria have been around for about 4 billion years. This means that bacteria were the dominating life form on Earth for about 3.5 billion years.
Many scientists still believe that bacteria are still the dominant life form. It is estimated that there kg by kg there are more bacteria on the Earth than all other life forms combined. This includes trees and plants animals and humans, insects and fish.
There are bacteria all over the Earth. There are bacteria on land and in water. There are bacteria in the soil and deep underground. There are bacteria flying in the air. There are also bacteria in the food we eat. There are bacteria both on the outside and inside every animal, plant and tree. There are also bacteria on every living human being, both on the skin and in the guts. In short, life on Earth are embedded in bacterial life.
Most of these bacteria are good. Bacteria on the skin keep the skin healthy. Bacteria in the gut help digest the food. Bacteria in the soil help plants grow. Bacteria in the water help clean the water.
Bacteria are simple organisms that consist of one cell. They are among the smallest living things. Most bacteria measure from 0.3 to 2.0 microns in diameter and can only be seen through a microscope. (One micron equals 0.001 millimeter).
Fig 1. Bacteria, such as these Streptococcus cells, cause many diseases, including ear infections, strep throat, and pneumonia
There are bacteria around that make us sick. These diseases include cholera, gonorrhea, leprosy, pneumonia, syphilis, tuberculosis, typhoid fever, and whooping cough. The bacteria enter a human being's body through its natural openings, such as the nose or mouth, or through breaks in the skin. In addition, air, food, and water carry bacteria from one person to another.
Certain kinds of bacteria live in the intestines of human beings and other animals. These bacteria help in digestion and in destroying harmful organisms. Intestinal bacteria also produce some vitamins needed by the body. There are also bacteria on the skin. Many of these bacteria keep the skin healthy and protect us against fungus infections.
When we get sick and take penicillin, we kill the bacteria that make us sick. That is good. But we also kill the bacteria that keep us healthy. That is not god. This is the reason why we sometimes get upset stomach when we get penicillin.
Fig 2. “Clean water”. The water in this drum is about tree feet deep. It is rainwater. It is also full of bacteria. It looks clean. The bacteria keep it clean. You can probably drink it without getting sick. The old leaves on the bottom are clearly visible through the water.
Bacteria keep the water clean. In the summer, when the sun shines, the still water like this will turn “green”. The green color comes from cyan bacteria, also called blue-green algae.
Fig 3. Cyan bacteria are tiny single celled organisms forming long strands. They live in still water. When the water is polluted with fertilizers or human or animal waste, the cyan bacteria may color the water totally green. Too many cyan bacteria in the water are an indication of pollution.
Bacteria in soil and water play a vital role in recycling carbon, nitrogen, sulfur, and other chemical elements used by living things. Many bacteria help decompose (break down) dead organisms and animal wastes into chemical elements. Other bacteria help change chemical elements into forms that can be used by plants and animals. For example, certain kinds of bacteria convert nitrogen in the air and soil into nitrogen compounds that can be used by plants. This means that soil is alive. In good soil unharmed by destructive farming, as much as 25% of the weight consists of bacteria.
We will have to remember that bacteria are living things. The farmer fertilizes the soil with ammonia. He does that to make the crop grow better. It does, because the plants need ammonia to grow. What is forgotten in the process is that the bacteria in the soil are also killed. The ammonia kills them. The very ammonia the farmer applies to the soil to make the plants grow kills many of the bacteria that make ammonia for the plants. In this way the soil slowly dies.
Bacteria are living things. They are alive like us. The same things that poison bacteria are also poisonous to human beings. We are all alike. We are all part of life on this planet. We are all living together. Together we make this planet alive.