Bizarre and Weird Bacteria Facts
Most people nowadays reckon they have a pretty good understanding of bacteria. Every since Pasteur, Koch and other bacteriology pioneers showed conclusively that many diseases were caused by bacteria, scientists and doctors have been fighting against them.
Mankind won a resounding victory when Alexander Flemming noticed that bread mould killed off the bacteria he was culturing on his agar plate, and discovered Penicillin. However, disease causing bacteria didn't give up so easily, helped by the overuse of antibiotics, resistant strains appeared. Nowadays, with strains such as MRSA, bacteria are far from vanquished.
However, most people's knowledge about bacteria is far more limited than they think. Below are some facts that might surprise you.
There are Many More Bacteria Cells in Your Body Than Human Cells
Of course, not all bacteria are harmful. Many have a symbiotic relationship with humans, we allow them to live in our bodies, while they carry out useful functions for us, or at least don't hurt us.
In fact a human body has many more bacteria cells than human cells. A number that is often mentioned is that there are 10x as many bacteria. The skin and the gut are two places where bacteria flourish. they carry out important functions such as producing vitamin K and biotin, and fermenting carbohydrates that hadn't yet been digested.
The Mitochondria in Your Cells are Thought to be Bacterial in Origin
But the relationship between bacteria and more complicated organisms is thought to be much more intimate than us merely providing a habitat for them. It is thought that ancestral bacteria went into making up the very cells of which we are made.
Our cells are much more complicated than bacteria. We, and other organisms, such as fungi, algae, plants, are made up of eukaryotic cells, which have a proper nucleus and specialised organelles. One of those, the mitochondria are responsible for producing energy for the cell. Mitochondria differ from other organelles in that they have their own DNA. Mitochondrial DNA is only inherited from the mother (unlike the DNA in the nucleus which is inherited from both parents).
The current theory, which has become generally accepted, is that mitochondria are in fact bacterial in origin. The theory goes that eukaryotic cells first arose, when simpler, proto-eukaryotic cells engulfed bacteria, which somehow were able to survive inside the cells. This is thought to have occurred around 2 billion years ago. Having these bacteria, which eventually became mitochondria, gave the eukaryotic cells the ability of generating energy by respiration, and a big evolutionary advantage.
Bacteria Have there own Germs
Harmful bacteria might be the cause of many of our diseases, but bacteria themselves are plagued by germs. There are special viruses, known as bacteriophages that prey on bacteria. Admittedly the don't give them a cold or measles, the name bacteriophage comes from a Greek word meaning "to devour".
A phage (as they are informally known) will attach to a bacterium and inject its DNA into it. After the virus had replicated into masses of new viruses, they burst open the cell and destroy it.
Bacteria have their own immune system.
Of course bacteria are not completely defenceless against viruses, they have evolved several ways of destroying them before being killed.
Since the only part of the bacteriophage that is injected into an infected bacterium is its DNA, the defence systems rely on recognising foreign DNA and destroying it. The difficult bit is distinguishing viral DNA from one's own, because chemically all DNA is the same.
One weapon that bacteria have developed against viruses are restriction enzymes, which cut DNA at very specific sequences. Those restriction sites are short, often 4-6 base pairs, and palindromic. For example the enzyme EcoRI from E.coli recognises the sequence GGAATTCC.
The bacterial DNA is methylated at those sequences which protects it from the enzymes.