Answer:
Oxygen, temperature, metabolism
Explanation:
Based on Oxygen: Microorganisms are grouped based on their oxygen requirement. This determines the kind of environment in which they can grow and thrive.
They could be:
Based on Temperature:
Temperature determines the types of environment as well as the type of processes they can undergo, as enzymes are temperature sensitive.
Based on Metabolism:
This determines the kind of substrates they can colonize, and the kind of host they can inhabit; whether they can make their own food or can be pathogenic.