Bacterial survival in microscopic surface wetness

Abstract
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Abstract

Plant leaves constitute a huge microbial habitat of global importance. How microorganisms survive the dry daytime on leaves and avoid desiccation is not well understood. There is evidence that microscopic surface wetness in the form of thin films and micrometer-sized droplets, invisible to the naked eye, persists on leaves during daytime due to deliquescence - the absorption of water until dissolution - of hygroscopic aerosols. Here we study how such microscopic wetness affects cell survival. We show that, on surfaces drying under moderate humidity, stable microdroplets form around bacterial aggregates due to capillary pinning and deliquescence. Notably, droplet-size increases with aggregate-size, and cell survival is higher the larger the droplet. This phenomenon was observed for 13 bacterial species, two of which - Pseudomonas fluorescens and P. putida - were studied in depth. Microdroplet formation around aggregates is likely key to bacterial survival in a variety of unsaturated microbial habitats, including leaf surfaces.

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All data generated or analysed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 2,3 and 5.

Article and author information

Author details

Maor Grinberg

Department of Plant Pathology and Microbiology, The Hebrew University of Jerusalem, Rehovot, Israel

Competing interests
The authors declare that no competing interests exist.
Tomer Orevi

Department of Plant Pathology and Microbiology, The Hebrew University of Jerusalem, Rehovot, Israel

Competing interests
The authors declare that no competing interests exist.
Shifra Steinberg

Department of Plant Pathology and Microbiology, The Hebrew University of Jerusalem, Rehovot, Israel

Competing interests
The authors declare that no competing interests exist.
Nadav Kashtan

Department of Plant Pathology and Microbiology, The Hebrew University of Jerusalem, Rehovot, Israel

For correspondence
nadav.kashtan@mail.huji.ac.il

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-7475-1363

Funding

James S. McDonnell Foundation (#220020475)

Nadav Kashtan

Israel Science Foundation (1396/19)

Nadav Kashtan

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.