Science Help. Bacteria

Question

I have a few questions about a science fair project:

Can UVA/UVB lights(from a light bulb) kill bacteria?

How can you tell whether bacteria is dead or alive?

If I had to test one kind of bacteria to see how long it takes a UVA/UVB light to kill it, which kind of bacteria should I use?

Thanks

Answer 1

Yes.

There are some stains that will only affect live ones, but the most reliable way is to swab the area and try to grow them.  Dead ones don't reproduce.

Lab E. coli.  Easy to grow, completely safe.

Answer 2

UVA light does kill bacteria.  If I were going to test aa bacteria, I would do Staphylococcus Aureus, cause it only takes about 1 minute.  

I guess there's lots of ways to tell if bacteria are alive or not.  You can look under a microscope, and if you know they are supposed to be motile, but they aren't, they might be dead.  If they are stained, they are dead. If their cell walls are lysed, or misshapen, broken, they are dead.  

Oh, and I don't know about UVB light, just UVA.