And why compare to the brain? Mostly because of complexity. I can't interface with a bacteria in any meaningful way, but I can interface with an LLM to a significant degree.
But you do. There are more bacterias in and on the body, than body cells. We are bacterias forming lasting bonds and we still interact with the free floating ones in various ways. Mainly in the gut and that has many effects, also on the brain, but also in various other ways we are beginning to understand.
https://en.wikipedia.org/wiki/Human_microbiome
So no idea about a microbiome consciousness - but who am I to know.
Bacteria are quite complex, btw.