What are pathogenic and opportunistic bacteria?
https://www.google.com/search?q=pathogenic+bacteria&oq=pathogenic&aqs=chrome.1.69i57j0j69i61j0l3.6240j0j7&sourceid=chrome&ie=UTF-8
https://www.google.com/search?q=opportunistic+bacteria&oq=opportunistic+bac&aqs=chrome.0.0j69i57j69i61l2j0l2.8194j0j7&sourceid=chrome&ie=UTF-8
