Wiley-Blackwell Acta Medica Okayama 20458827 3 2 2014 Isolation of viable but nonculturable Vibrio cholerae O1 from environmental water samples in Kolkata, India, in a culturable state 239 246 EN Mitsutoshi Senoh Collaborative Research Center of Okayama University for Infectious Diseases in India, Okayama University Jayeeta Ghosh-Banerjee National Institute of Cholera and Enteric Diseases, Tamaki Mizuno Collaborative Research Center of Okayama University for Infectious Diseases in India, Okayama University Sumio Shinoda Collaborative Research Center of Okayama University for Infectious Diseases in India, Okayama University Shin-ichi Miyoshi Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takashi Hamabata Research Institute, National Center for Global Health and Medicine G. Balakrish Nair Translational Health Science and Technology Institute Yoshifumi Takeda Collaborative Research Center of Okayama University for Infectious Diseases in India, Okayama University Previously, we reported that viable but nonculturable (VBNC) Vibrio cholerae was converted into a culturable state by coculture with several eukaryotic cell lines including HT-29 cells. In this study, we found that a factor converting VBNC V. cholerae into a culturable state (FCVC) existed in cell extracts of eukaryotic cells. FCVC was nondialyzable, proteinase K-sensitive, and stable to heating at <60°C for 5 min. We prepared thiosulfate citrate bile salts sucrose (TCBS) plates with FCVC (F-TCBS plates). After confirming that VBNC V. cholerae O1 and O139 formed typical yellow colonies on F-TCBS plates, we tried to isolate cholera toxin gene-positive VBNC V. cholerae from environmental water samples collected in urban slum areas of Kolkata, India and succeeded in isolating V. cholerae O1 El Tor variant strains harboring a gene for the cholera toxin. The possible importance of VBNC V. cholerae O1 as a source of cholera outbreaks is discussed. No potential conflict of interest relevant to this article was reported.

Elsevier Acta Medica Okayama 0882-4010 51 4 2011 Enterotoxigenic Escherichia coli CS6 gene products and their roles in CS6 structural protein assembly and cellular adherence 243 249 EN Takeaki Wajima Subrata Sabui Megumi Fukumoto Shigeyuki Kano Thandavarayan Ramamurthy Nabendu Sekhar Chatterjee Takashi Hamabata Enterotoxigenic Escherichia coli (ETEC) produces a variety of colonization factors necessary for attachment to the host cell, among which CS6 is one of the most prevalent in ETEC isolates from developing countries. The CS6 operon is composed of 4 genes, cssA, cssB, cssC, and cssD. The molecular mechanism of CS6 assembly and cell surface presentation, and the contribution of each protein to the attachment of the bacterium to intestinal cells remain unclear. In the present study, a series of css gene-deletion mutants of the CS6 operon were constructed in the ETEC genetic background, and their effect on adhesion to host cells and CS6 assembly was studied. Each subunit deletion resulted in a reduction in the adhesion to intestinal cells to the same level of laboratory E. coli strains, and this effect was restored by complementary plasmids, suggesting that the 4 proteins are necessary for CS6 expression. Bacterial cell fractionation and western blotting of the mutant strains suggested that the formation of a CssA–CssB–CssC complex is necessary for recognition by CssD and transport of CssA–CssB to the outer membrane as a colonization factor. No potential conflict of interest relevant to this article was reported.