In microbiology, even in food microbiology it is important to know the differences between certain classes of microorganisms. One important grouping concerns the prokaryotes which are classified into either bacteria and archaea.
The archaea are generally thought of as a much older group of organisms. The main differences are:-
- The archaea are not inhibited by antibiotics, unlike the bacteria.
- Bacterial cell walls contain peptidoglycan or murein as it is known in some examples. the archaea do not have peptidoglycan in their cell walls.
- The archaea are extremophiles which means they thrive in ‘extreme’ conditions which bacteria cannot survive in. In a number of species, some archaea live well above 100 Centigrade or in environments where they can metabolise methane and sulphur based compounds. These properties have been cited for their extreme age and may well have thrived on the Earth before the bacteria evolved.
- Bacteria have just one ribosomal RNA polymerase (rRNA) whilst the archaea possess three ribosomal RNA polymerases. The Archaea in this respect are similar to eukaryotes.