Cultures of a bacterial species were incubated on the shelf of a refrigerator, out on a lab bench top, on the shelf of a 37°C in
cubator and on the shelf of a 50°C incubator. After incubation, there was no growth at 37°C and 50°C, slight growth out on the bench top and abundant growth at refrigeration. What term could be used for this species? A. Halophile
B. Mesophile
C. Anaerobe
D. Psychrophile
E. Capnophile
Psychrophiles or cryophiles are a type of extremophiles i.e. they live in extreme environment. They grow well in low temperatures ranging from -20 to +10 degree Celsius.
Here, the bacteria was incubated at different temperatures. It did not show growth at standard incubation temperature of 37°C which indicates that it might be an extremophile preferring either very hot or very cold environment. But it also did not show growth at 50°C which means that it does not survive well at high temperature.
Lab bench top has generally colder surface compared to the surrounding environment and a little growth was observed there which indicates that this bacteria might require cold temperature for growth. The result was finally confirmed with abundant growth observed inside refrigerator which is only possible if it is a psychrophile.
There are lots of transitional organisms in the fossil record though it does take very specific and precise conditions for a fossil to be preserved, a deer that dies in a field will not end up in the fossil record so we are looking at a small sampling of the evidence (and a good thing too or there wouldn't be anywhere to walk with all the bones laying around)
