**4.2 Culture-independent identification of gastric microbiota**

Culture-independent studies use a variety of molecular methods based on 16S rRNA gene sequencing. A multitude of reasons define these methods as far superior to those which are culture-dependent. These include:


A variety of 16S rRNA based methods exist, including:


In an extensive review of eight culture-independent studies, Sheh A. and Fox J. concluded that the most prominent phyla in the stomach are *Proteobacteria*, *Firmicutes*, *Bacteroidetes*, *Actinobacteria*, and *Fusobacteria* [33]. Furthermore, the most abundant phyla in *H. pylori*-positive subjects are *Proteobacteria*, *Firmicutes*, and *Actinobacteria*. In the absence of *H. pylori*, the most abundant phyla are *Firmicutes*, *Bacteroidetes*, and *Actinobacteria*. However, *H. pylori* remains the most dominant species in the stomach, comprising 72–99% of sequencing reads [10, 34]. In the absence of *H. pylori*, analysis consistently shows the presence of *Streptococcus* spp., which seem to be the most abundant genus in *H. pylori*-negative subjects [3, 30, 35, 36]. In the gastric microbiota, the non-*Helicobacter* genera commonly detected are *Streptococcus*, *Prevotella*, *Veillonella*, and *Rothia.*
