Enzymes are (usually) specific to the substrates they bind to. Thus, each enzyme has one and only one substrate structure they can metabolize, so even substrates with similar structures cannot be broken down by an enzyme specific to one of them.
Psychrotrophs are those bacteria which can tolerate cold temperature and have optimum growth above 15 degree Celsius.
Halophiles prefer high salt concentration.
Mesophiles prefer temperatures with a average of 37 degree Celsius.
Anaerobes grow in absence of oxygen.
In the given experiment, none of the bacterial cultures were placed in saline or anaerobic conditions. So, the bacterial species is not an anaerobe or halophile.
Again the cultures did not show growth at 37 degree celsius so they are not mesophiles.
Maximum growth at 22 degree celsius and a little growth in refrigerator make it obvious that the species is a Psychrotroph.
