Ta da ......
Two pints, obviously.
Unless you mean an hour *later*, which then there's 2^(60) pints of microbe.
Stahp with the math problems! I can't *not* do a math problem if I see one, and I need to get started on my homework D:
1 pint plus one microbe. You never said the doubled microbes also double every sixty seconds - just that the "certain" microbe doubles- not the others ;)