What important scientific advance made bacteria less dangerous to humans

everyone can get behind studying bacteria that cause life-threatening diseases like typhoid fever and cholera, I think that it is often harder to convince people of the value of studying ordinary and sometimes obscure bacteria that do not directly affect human health.

Explanation:

there are men and women, some choose to be both or change their gender. often times those people go by "other". those who change their gender are known as "transgender"