The microbial groups associated with foods are bacteria, fungi, protozoa, algae, and viruses. This is the main factor in deciding which conditions are most favorable for microbial food production since each type of microorganism as well as each individual strain of that microorganism will require different conditions to thrive. The optimal conditions for one microorganism will certainly be different from another microorganism in factors such as PH, temperature, moisture level, type of environment (type of food it is growing in), amount of food, etc.