A micro-organism or microbe is an organism that is too small to be seen with the naked eye. Only when there are many do they become visible. The most important examples of micro-organisms are viruses, bacteria, fungi, yeasts and algae. Bacteria are the most common and are about 1 micrometer in size, which is a thousandth of a millimeter (1000 bacteria in a row is not more than 1 millimeter)! Micro-organisms can be found everywhere in nature. In large numbers, they occur on the skin, in the digestive tract, in the soil, in water and in the air. The majority of micro-organisms are benign, useful or even necessary for humans, animals and the environment.

Some examples where micro-organisms are very useful:

  • Digestion: our food cannot be digested without the billions of bacteria in
    our gut
  • Composting: dead material from nature (eg leaves, grass, dead animals) are processed by microorganisms into the smallest nutrients, then naturally reused to form new plants or animals.
  • Food production: a lot of food can only be made using microorganisms such as yeast for bread and wine, or bacteria for yogurt and cheese.

There are unfortunately a number of micro-organisms that are harmful to humans, animals or the environment, which we call pathogens. Although they are a minority, they give the microorganisms a very bad reputation.

Some examples of micro-organisms that are harmful:

  • Disease: different microorganisms can cause diseases such as colds, pneumonia, flu, wound infection, tetanus, … Plants can be made sick by microorganisms, making them unable to bear any fruits or sometimes causing death.
  • Food Spoilage: mainly bacteria can cause spoiled or contaminated food which we get colitis and diarrhea after eating this food. Salmonella, E. coli, Listeria and Clostridium are the most important forms of these bacteria.