Final answer:
The contaminant in a forgotten soup container in the refrigerator is most likely psychrophiles, which is due to their ability to grow at low temperatures that are typical of refrigerated environments.
Step-by-step explanation:
If a soup container that was forgotten in the refrigerator shows contamination, the contaminants are likely to be psychrophiles. Psychrophiles are microorganisms that grow best at low temperatures, typically around 15 °C or lower but can grow at temperatures up to 20 °C. Refrigerators are set to temperatures below this range to preserve food by inhibiting the growth of most bacteria, except psychrophiles, which thrive in such cold environments.
For example, when exploring cold environments like Lake Whillans in Antarctica, researchers find psychrophiles that have adapted to their extreme habitat through modifications of their cell membranes and the use of antifreeze compounds. Meanwhile, bacteria isolated from a hot tub at 39 °C or from warm environments like a 35 °C incubator are likely to be mesophiles, which grow best in moderate temperatures generally ranging from 20 °C to 45 °C. On the hotter end of the spectrum, thermophiles grow best at temperatures above 50 °C, with hyperthermophiles having optimum growth temperatures close to boiling water.