Bacteria (from Greek: bakterion ? little stick) are one of the three fundamental domains, in which life is divided nowadays. They are microscopically small and were first detected in ponds and human saliva by Antoni van Leeuwenhoek in 1676 using a self-made microscope. The biggest bacterium found to date can even be seen with the naked eye and was detected in 1999. So to speak, it is the blue-whale among the bacteria.