Abstract
Background: Scientists previously believed that bacteria could not grow in bile, which is rich in bacteriostatic compounds such as bile acids. Therefore, the biliary tract was considered to be a sterile environment. However, high-throughput (i.e., amplicon) sequencing analysis methods have recently been used to discover the bacterial flora in gallbladder bile in brain-dead patients with normal gallbladders. In a bacterial flora analysis targeting the 16S ribosomal gene, a specific flora was present in the bile of normal gallbladders. However, these results were not obtained from truly healthy individuals. Therefore, the aim of this study was to analyze the microbial flora of bile collected from pathologically normal gallbladders that were surgically removed from patients with hepatobiliary pancreatic diseases who had normal liver function.Results: All 12 bile samples obtained from the gallbladders had negative culture results, although a bacterial flora was detected in all samples via 16S ribosome gene analysis. The composition of the bacterial flora was very simple, and the Firmicutes, Proteobacteria, and Actinobacteria phyla were identified in all samples. Based on 16S rRNA gene profile analysis, the composition ratio accounted for more than 80% of the total number of reads. The Anaerobacillus, Delftia, Bacillus, Ralstonia, Ochrobactrum, Acidovorax, and Curvibacter genera were detected in all 12 samples. Based on 16S rRNA gene profile analysis, at the genus level, Anaerobacillus and Delftia accounted for 58.62%–87.63% of the identified bacteria in each sample. Conclusions: In this study, the bacterial flora in the gallbladder bile was not diverse. Contrary to previous reports, few bacteria belonging to the Bacteroidetes phylum were detected. The functional significance of the gallbladder bacterial flora requires further investigation.
Metagenomic 16S rRNA gene sequencing survey of Borrelia species in Irish samples of Ixodes ricinus ticks
