noun
bacteriologist
A scientist who studies bacteria.
彼女は大学で細菌学者として研究している。
She conducts research as a bacteriologist at the university.
細菌学 is the field of bacteriology, while 細菌学者 is a person who specializes in it.
Compound of 細菌 (bacteria) + 学 (study) + 者 (person).