The gut microbiome is the community of microorganisms living in the digestive tract. Bacteria are only one part of this community; viruses, fungi and other microbes also belong in the wider picture.
A diverse microbiome is shaped by many factors, including food patterns, age, environment, illness and medicines. No single test or food choice describes the whole ecosystem.
What you eat feeds something. A varied pattern of minimally processed plant foods can provide different fibres and other compounds for microbes to use. The best approach is one that suits your health, access and tolerance.
Key idea: balance and context matter more than trying to eliminate every microbe.