Study of structure responsible for biofilm formation and quorum-sensing genes in Vibrio cholerae isolated at the Far East of Russia

Vibrio cholerae is the causative agent of acute dehydrating diarrheal disease that occurs in epidemic form. It is considered that the first six pandemics were caused by V. cholerae of classical biovar however the last pandemic, started in 1961, was caused by biovar El Tor. Russia has a risk of cholera importations because of occurrence of cholera foci in Asian countries. Two key factors for environmental survival of vibrions are the ability to form biofilms and quorum-sensing mechanism — a process of cell–cell communication.

In this study we explored genes that are responsible for these mechanisms in genomes of V. cholerae strains from different ecological niches isolated at the Far East of Russia. The first strain I-1300 O1 serogroup was received from a patient during cholera outbreak in Uzhno-Sachalinsk and the other one – 102-16 (R-variant) from lake Solenoye in Nakhodka. V. cholerae N16961 was used as a reference genome to compare genes structure. 35 main genes responsible for biofilm formation and quorum-sensing were chosen for analysis based on published data. Genomes were sequenced with 454 technology. V. cholerae I-1300 turned out to be similar to the reference genome: all genes in all assemblies without SNPs were presented. The de novo assembly of V. cholerae 102-16 showed significant differences between this genome and the reference one: mshA and 5 genes from vpsI cluster were absent, only 26 genes were fully presented and 3 partial. Only luxS gene was identical to the reference, another 25 genes had nonsynonymous SNPs in their structure. Thus, genome of R-variant has major differences in structure of biofilm formation genes, that are only first findings that need further investigation.