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Protozoal ciliate promotes bacterial autoinducer-2 accumulation in mixed culture with Escherichia coli

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Title: Protozoal ciliate promotes bacterial autoinducer-2 accumulation in mixed culture with Escherichia coli
Authors: Oguri, Satoshi Browse this author
Hanawa, Tomoko Browse this author
Matsuo, Junji Browse this author →KAKEN DB
Ishida, Kasumi Browse this author
Yamazaki, Tomohiro Browse this author
Nakamura, Shinji Browse this author →KAKEN DB
Okubo, Torahiko Browse this author
Fukumoto, Tatsuya Browse this author
Akizawa, Kouzi Browse this author
Shimizu, Chikara Browse this author →KAKEN DB
Kamiya, Shigeru Browse this author
Yamaguchi, Hiroyuki Browse this author →KAKEN DB
Keywords: autoinducer-2
Escherichia coli
quorum sensing
Tetrahymena thermophila
Issue Date: 2015
Publisher: 応用微生物学・分子細胞生物学研究奨励会
Journal Title: The Journal of General and Applied Microbiology
Volume: 61
Issue: 5
Start Page: 203
End Page: 210
Publisher DOI: 10.2323/jgam.61.203
PMID: 26582290
Abstract: We have previously demonstrated conjugation of Escherichia coli into vacuoles of the protozoal ciliate (Tetrahymena thermophila). This indicated a possible role of ciliates in evoking bacterial quorum sensing, directly connecting bacterial survival via accumulation in the ciliate vacuoles. We therefore assessed if ciliates promoted bacterial autoinducer (AI)-2 accumulation with vacuole formation, which controls quorum sensing. E. coli AI-2 accumulation was significantly enhanced in the supernatants of a mixed culture of ciliates and bacteria, likely depending on ciliate density rather than bacterial concentration. As expected, AI-2 production was significantly correlated with vacuole formation. The experiment with E. coli luxS mutants showed that ciliates failed to enhance bacterial AI-2 accumulation, denying a nonspecific phenomenon. Fluorescence microscopy revealed accumulation of fragmented bacteria in ciliate vacuoles, and, more importantly, expulsion of the vacuoles containing disrupted bacteria into the culture supernatant. There was no increase in the expression of luxS (encoding AI-2) or ydgG (a transporter for controlling bacterial export of AI-2). We conclude that ciliates promote bacterial AI-2 accumulation in a mixed culture, via accumulation of disrupted bacteria in ciliate vacuoles followed by expulsion of the vacuoles, independently of luxS or ydgG gene induction. This is believed to be the first demonstration of a relationship between E. coli AI-2 dynamics and ciliates. In the natural environment, ciliate biotopes may provide a survival advantage to bacteria inhabiting such biotopes, via evoking quorum sensing.
Rights: ©2015 Applied Microbiology, Molecular and Cellular Biosciences Research Foundation
Type: article
Appears in Collections:保健科学院・保健科学研究院 (Graduate School of Health Sciences / Faculty of Health Sciences) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 山口 博之

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