The prefix that changes the meaning of bacterial from "relating to or caused by bacteria" to "preventing bacteria" is anti-
The prefix anti means “against,” “opposite of,” “antiparticle of,” used in the formation of compound words ( anticline ); used freely in combination with elements of any origin ( antibody; antifreeze; antiknock; antilepton ).
Prefixes are letters which added to the beginning of a word in order to make a new word with a different meaning. Prefixes can, for instance, create a new word opposite in meaning to the word the prefix is attached to.
The connection that can be made between european treatment of colonial native populations and the character of Caliban is The European took away the native population's freedom and Prospero, one of the character in Caliban took away Caliban's freedom