IPA: //bækˌtɪəriˈɒlədʒɪst//
KK: /bækˌtɪrɪˈɒlədʒɪst/
A scientist who studies bacteria and their effects on living organisms and the environment.
The bacteriologist conducted research to find new antibiotics.
Bacteriologist → It is formed from "bacterium" (from Greek "bakterion", meaning rod or staff) and "-logist" (from Greek "logia", meaning study or science). A bacteriologist is someone who studies bacteria.
Think of someone who studies 'bacteria' ('bacterium' means rod) and the '-logist' part means they are a specialist in that field.