Not a microbiologist but my ideas are:
- frequency (exotic organisms might be difficult to get/culture)
- ability to form spores or similar (reason for heat stability and longevity)
- pathogenicity (less is better)
- ease of detection (a long time of cultivation until you see a colony or not is not good)
A good example is this one: https://en.wikipedia...arothermophilus
One must presume that long and short arguments contribute to the same end. - Epicurus
...except casandra's that did belong to the funniest, most interesting and imaginative (or over-imaginative?) ones, I suppose.