Nanaerobic growth enables direct visualization of dynamic cellular processes in human gut symbionts

García-Bayona, Leonor and Coyne, Michael J. and Hantman, Noam and Montero-Llopis, Paula and Von, Salena S. and Ito, Takeshi and Malamy, Michael H. and Basler, Marek and Barquera, Blanca and Comstock, Laurie E.. (2020) Nanaerobic growth enables direct visualization of dynamic cellular processes in human gut symbionts. Proceedings of the National Academy of Sciences of the United States of America, 117 (39). pp. 24484-24493.

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Mechanistic studies of anaerobic gut bacteria have been hindered by the lack of a fluorescent protein system to track and visualize proteins and dynamic cellular processes in actively growing bacteria. Although underappreciated, many gut "anaerobes" are able to respire using oxygen as the terminal electron acceptor. The oxygen continually released from gut epithelial cells creates an oxygen gradient from the mucus layer to the anaerobic lumen [L. Albenberg et al., Gastroenterology 147, 1055-1063.e8 (2014)], with oxygen available to bacteria growing at the mucus layer. Here, we show that; Bacteroides; species are metabolically and energetically robust and do not mount stress responses in the presence of 0.10 to 0.14% oxygen, defined as nanaerobic conditions [A. D. Baughn, M. H. Malamy, Nature 427, 441-444 (2004)]. Taking advantage of this metabolic capability, we show that nanaerobic growth provides sufficient oxygen for the maturation of oxygen-requiring fluorescent proteins in; Bacteroides; species. Type strains of four different; Bacteroides; species show bright GFP fluorescence when grown nanaerobically versus anaerobically. We compared four different red fluorescent proteins and found that mKate2 yields the highest red fluorescence intensity in our assay. We show that GFP-tagged proteins can be localized in nanaerobically growing bacteria. In addition, we used time-lapse fluorescence microscopy to image dynamic type VI secretion system processes in metabolically active; Bacteroides fragilis; The ability to visualize fluorescently labeled; Bacteroides; and fluorescently linked proteins in actively growing nanaerobic gut symbionts ushers in an age of imaging analyses not previously possible in these bacteria.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Infection Biology > Infection Biology (Basler)
UniBasel Contributors:Basler, Marek
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:National Academy of Sciences
Note:Publication type according to Uni Basel Research Database: Journal article
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edoc DOI:
Last Modified:30 Dec 2020 13:55
Deposited On:30 Dec 2020 10:06

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