ACE2 and COVID-19: Furthermore, Zuo et al. [19] observed not only that some bacterial strains in the gut (Bacteroides dorei, Bacteroides thetaiotaomicron, Bacteroides massiliensis, and Bacteroides ovatus) that are correlated inversely with SARS-CoV-2 in fecal samples from patients have been decreasing in the expression of ACE2 in murine gut, but also, they have observed a correlation of the abundance of Coprobacillus, Clostriudium ramosum, and Clostridium hathewayi with COVID-19 severity [19].