germs; microorganisms; saprophytic bacteria
Refers to various microorganisms, often with a negative connotation of unwanted or harmful germs. In biological contexts, it can specifically denote saprophytes or saprophytic bacteria that feed on dead organic matter.
There are many germs on your hands.
Store food in the refrigerator to prevent germs from multiplying.
殺菌 (さっきん, to kill germs) and 雑菌 (ざっきん, miscellaneous/random germs) sound similar but 雑菌 is a noun for the germs themselves, not an action.
Compound of 雑 (ざつ, miscellaneous) and 菌 (きん, bacteria/fungus). The reading ざっきん results from rendaku voicing of きん to ぎん and gemination of つ to っ.