Espinoza-Vergara, G, Hoque, MM, McDougald, D & Noorian, P 2020, 'The Impact of Protozoan Predation on the Pathogenicity of Vibrio cholerae', FRONTIERS IN MICROBIOLOGY, vol. 11.View/Download from: Publisher's site
Naser, IB, Hoque, MM, Faruque, SN, Kamruzzaman, M, Yamasaki, S & Faruque, SM 2019, 'Vibrio cholerae strains with inactivated cqsS gene overproduce autoinducer-2 which enhances resuscitation of dormant environmental V. cholerae.', PLoS One, vol. 14, no. 10.View/Download from: Publisher's site
BACKGROUND: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. METHODS: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. RESULTS: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. SIGNIFICANCE: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. Fu...
Espinoza-Vergara, G, Noorian, P, Silva-Valenzuela, CA, Raymond, BBA, Allen, C, Hoque, MM, Sun, S, Johnson, MS, Pernice, M, Kjelleberg, S, Djordjevic, SP, Labbate, M, Camilli, A & McDougald, D 2019, 'Vibrio cholerae residing in food vacuoles expelled by protozoa are more infectious in vivo', Nature Microbiology, vol. 4, no. 12, pp. 2466-2474.View/Download from: Publisher's site
Bin Naser, I, Hoque, MM, Abdullah, A, Bari, SMN, Ghosh, AN & Faruque, SM 2017, 'Environmental bacteriophages active on biofilms and planktonic forms of toxigenic Vibrio cholerae: Potential relevance in cholera epidemiology', PLOS ONE, vol. 12, no. 7.View/Download from: Publisher's site
Bin Naser, I, Hoque, MM, Nahid, MA, Tareq, TM, Rocky, MK & Faruque, SM 2017, 'Analysis of the CRISPR-Cas system in bacteriophages active on epidemic strains of Vibrio cholerae in Bangladesh', SCIENTIFIC REPORTS, vol. 7.View/Download from: Publisher's site