Microbiology Musings — 1. How old are the bacteria on this 18 hours plate
So in microbiology, we usually culture bacteria for a finite amount of time, e.g overnight, to obtain a bacteria culture of a certain age 16–18 hours. With the bacteria at the age of 16–18 hours most commonly encountered bacteria are at the phase of “exponential growth” and we can do further testing on them.
However is a bacteria cultured for 16–18 hours really 16–18 hours old?
Bacteria reproduce by “binary fission” where bacteria essentially makes an extra copy of its own DNA and other goodies, put these copies in separate end inside itself, build a new wall inside itself and when the two ends separate, two “new” bacteria are formed!
The following wiki link will give you more details if you want to know more.
BUT wait, the two “new” bacteria are actually one “old” bacteria and one “new bacteria”! One of them will have the “old” copy of the DNA and other goodies and the other the “new copy” and other goodies.
Now, extrapolate this process back million and billion times, then suddenly this bacteria on my culture plate could potentially be traced back to the first bacteria that roamed this earth!
Wait a minute, so does that mean the first bacteria looks exactly like the bacteria on my plate? And given bacteria are the most primitive life form (so you were told) is this bacteria on my plate representative of the earliest life form on earth? That doesn’t make any sense. But the exploration of this will come as another musing.