The first thing I want to comment on in this blog post is the difference between a microbial population and a microbial community. The former denotes a group of microbes belonging to a single species while the latter refers to multiple species living together. The characteristics of a microbial population can include the carbon, nitrogen, and terminal electron acceptor they are able to use to survive, optimal temperature, oxygen tolerance, salt tolerance, optimal substrate concentration, pigmentation, biofilm formation, method of or ability to quorum sense. However, it is important to note that many of these are not specific to the microbial population and are theoretically characteristics of the individual microbe as well if it can be cultured in an isolated fashion. The most likely exceptions to this would be quorum sensing and/or other methods of communication and biofilm formation (a result of microbial communication).
The relationship between the characteristics within a microbial population and community very much depends on the microbe. Most microbes cannot be cultured on their own which means that while a characteristic may at first glance be specific to a single microbe, it may better qualify as community characteristics since it does not exist outside a community. This is further supported by the fact that if they cannot grow by themselves then they cannot form an isolated microbial population, given the definition as I understand it.
A question I would have regarding this is “Does the effect a pathogenic microbe has on another organism fall into a population or community characteristic? For example, enterotoxin producing E. coli straining to live in the human gut will generally cause the host to get sick and one could assert that it alone is causing this to happen. After all, it is producing the enterotoxin. However, this produces questions like does this strain of E. coli still produce the enterotoxin in a population setting as it does in the community setting present in the gut? Does this strain of E. coli make a gnotobiotic mouse sick in the same way it makes a mouse with a standard microbiome sick? The answers to these questions determine if this characteristic is community or population-based. This also highlights how the characteristics of a microbial community versus a microbial population are not always cut and dry.
