Vibrio cholerae strains with inactivated cqsS gene overproduce autoinducer-2 which enhances resuscitation of dormant environmental V. cholerae

Autoři: Iftekhar Bin Naser aff001;  M. Mozammel Hoque aff003;  Shah Nayeem Faruque aff004;  M. Kamruzzaman aff003;  Shinji Yamasaki aff005;  Shah M. Faruque aff001
Působiště autorů: School of Life Sciences, Independent University Bangladesh, Dhaka, Bangladesh aff001;  Department of Mathematics and Natural Sciences, BRAC University, Dhaka, Bangladesh aff002;  Laboratory Sciences and Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh aff003;  Department of Biochemistry and Microbiology, North South University, Dhaka, Bangladesh aff004;  Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Osaka, Japan aff005
Vyšlo v časopise: PLoS ONE 14(10)
Kategorie: Research Article
doi: 10.1371/journal.pone.0223226



Toxigenic Vibrio cholerae resides in aquatic reservoirs of cholera-endemic areas mostly in a dormant form known as conditionally viable environmental cells (CVEC) in which the bacteria remain embedded in an exopolysaccharide matrix, and fail to grow in routine bacteriological culture. The CVEC can be resuscitated by supplementing culture media with either of two autoinducers CAI-1 and AI-2, which are signal molecules controlling quorum sensing, a regulatory network of bacterial gene expression dependent on cell density. This study investigated possible existence of variant strains that overproduce AIs, sufficient to resuscitate CVEC in environmental waters.


Environmental V. cholerae isolates and Tn insertion mutants of a V. cholerae strain C6706 were screened for production of AIs using bioluminescent reporter strains. Relevant mutations in environmental strains which overproduced AI-2 were characterized by nucleotide sequencing and genetic complementation studies. Effect of AIs produced in culture supernatants of relevant strains on reactivation of CVEC in water was determined by resuscitation assays.


Two of 54 environmental V. cholerae isolates were found to overproduce AI-2. Screening of a Tn-insertion library of V. cholerae strain C6706, identified a mutant which overproduced AI-2, and carried Tn insertion in the cqsS gene. Nucleotide sequencing also revealed mutations inactivating the cqsS gene in environmental isolates which overproduced AI-2, and this property was reversed when complemented with a wild type cqsS gene. Culture of river water samples supplemented with spent medium of these mutants resuscitated dormant V. cholerae cells in water.


V. cholerae strains with inactivated cqsS gene may offer a convenient source of AI-2 in enhanced assays for monitoring bacteriological quality of water. The results also suggest a potential role of naturally occurring cqsS mutants in the environmental biology of V. cholerae. Furthermore, similar phenomenon may have relevance in the ecology of other waterborne bacterial pathogens beyond V. cholerae.

Klíčová slova:

Bacterial pathogens – Mutant strains – Nucleotide sequencing – Plasmid construction – Resuscitation – Vibrio cholerae – Gene cloning – Bioluminescence


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2019 Číslo 10