Dysbiosis of the microbiome forms a new internal environment, under which it may affect the development of GERD from the perspectives of molecular mechanisms: microbial activation of Toll-like receptors, microbial stimulation of cyclooxygenase-2 expression, microbial stimulation of inducible nitrous oxide synthase, and activation of the NLRP3 inflammatory vesicle; immune mechanisms; and impact on the dynamics of the lower gastrointestinal tract. The gene discussed is PTGS2; the disease is gastroesophageal reflux disease.