I also have GERD without many symptoms. Have you done an upper endoscopy, a barium swallow, and been tested for _H. Pylori_?

I did all of it, which showed mild damage to my esophagus, as well as some signs of stomach inflammation, which I thought was interesting. The radiologist said "everything is just coming right back up" and told me I had severe GERD. Negative for _H. Pylori_.

PPIs (lansaprazole, omeprazole) appeared to do nothing, so I stopped, given that the long-term health risks are negative.

Interesting that you think gut bacteria are related. In medical terms the gut refers to the intestines, not the stomach. I assume you mean stomach bacteria here. There's apparently not a lot that can survive the environment of the stomach, but strep bacteria can.

I recently read that getting more fiber in one's diet can help GERD.