Re: Term for organisms evolved to live in hot and cold temperatures?

hi Sarah,

I worked on thermal adaptation in microorganisms for 6 years and I've never come across a specific word or term for the situation that you describe. Of course, there are so many words in the English language that I wouldn't be surprised if one existed.

In microbiology at least, it's common to use the term "strain" when we describe an organism of the same species with different characteristics. For instance, "a pathogenic strain of E. coli". So most people would use an adjective followed by the word "strain".

In the case of thermal adaptation, we have 3 broad classes of organisms. Psychrophiles have an optimum growth temperature (OGT) of less than 20 °C. The "psychro-" prefix is from the Greek psukhros, meaning cold and -phile is to like, or to love. Organisms that grow at what we consider to be "normal" environmental temperatures (20 - 45 °C) are mesophiles. Those that like it above 45 °C are thermophiles. There are a few variations on this theme. Organisms with an OGT above 80 °C might be termed hyperthermophiles. Organisms that can grow at low temperature, but don't especially thrive in the cold might be called psychrotolerant, or psychrotrophic.

So in the literature, you will see articles with titles like:
Multiple-locus sequence typing analysis of Bacillus cereus and Bacillus thuringiensis reveals separate clustering and a distinct population structure of psychrotrophic strains [PubMed link]
Discrimination of psychrotrophic and mesophilic strains of the Bacillus cereus group by PCR targeting of major cold shock protein genes [PubMed link]

and strains are often designated using a code, e.g. Bacillus cereus TZ415 refers to a psychrophilic strain, distinct from other strains of that species.