This is them! First inhabitants of Earth, first to experiment life. Respect for these tiny beasts so!
But what is it? We often hear them in news as responsible for infections or sickness. As the Lactalis scandal with the contaminated milk by a Salmonella.
Bacteria size is between 0.5 and 5µm so they are very small organisms, nearly the cell size… In fact, except exception, a bacterium is only a cell (unicellular organism).
But then if they measure less than 5µm, how do you can take a photo of them? Well, bacteria can live in colonies, each “small canelé” that you see on the photo is a colony composed of thousands of bacteria.
Bacteria are everywhere, in all kind of environments (ocean, on a rock, in the soil, on roots, inside the digestive tube, …). By the way, you have them everywhere on your body, it’s them they make you stink or help you to digest food.
Being small beasts, they are numerous (without automatically colonies formation), if you want a magnitude scale there are more bacteria in your mouth than humans on Earth!
Don’t worry, it’s normal, we live with them from time immemorial.
Shape diversity is relatively rich, but they are generally round (cocci) or stick shape (bacilli).
That is when you look bacteria with a microscope (bacilli first and then filamentous, magnified by 400 or 1000).
And how they can work with only one cell? In fact, being organisms, which colonizing every environment, they have a big diversity of machinery. I’m going to take advantage to define some terms.
Are they produce their food, or they eat that of others? We talk about autotroph and heterotroph respectively.
Trophê (food), heteros (other) and autos (autonomous in Greek).
Among the autotroph, there is the bacteria which use sun energy (phototroph) and those using chemical elements, especially sulfur (chemotroph).
In heterotroph, there are the bacteria which feed by harvesting food on living, dead organisms and also on organisms’ residues like dead leaves.
Bacteria which using sun? I thought that it’s was plants which have invented that!
Good remark! Well, let’s say that plants did a bit of industrial espionage, I will explain to you that when we will talk about plants apparition.
But what proves us that they are living organisms? What defines a living thing? Good question! It’s the next subject!
http://www.lefigaro.fr/conjoncture/2018/02/02/20002-20180202ARTFIG00330-le-scandale-lactalis-chronologie-d-une-crise-commencee-en-2005.php
https://fr.wikipedia.org/wiki/Bact%C3%A9rie
https://fr.wikipedia.org/wiki/H%C3%A9t%C3%A9rotrophie
https://fr.wikipedia.org/wiki/Autotrophie
Your questions are welcome!
