Xenorhabdus nematophila bacteria shift from mutualistic to virulent Lrp‐dependent phenotypes within the receptacles of Steinernema carpocapsae insect‐infective stage nematodes
- Creators
- Cao, Mengyi
- Goodrich-Blair, Heidi
Abstract
Xenorhabdus nematophila bacteria are mutualists of Steinernema carpocapsae nematodes and pathogens of insects. Xenorhabdus nematophila exhibits phenotypic variation between insect virulence (V) and the mutualistic (M) support of nematode reproduction and colonization initiation in the infective juvenile (IJ) stage nematode that carries X. nematophila between insect hosts. The V and M phenotypes occur reciprocally depending on levels of the transcription factor Lrp: high‐Lrp expressors are M+V− while low‐Lrp expressors are V+M−. We report here that variable (wild type) or fixed high‐Lrp expressors also are optimized, relative to low‐ or no‐Lrp expressors, for colonization of additional nematode stages: juvenile, adult and pre‐transmission infective juvenile (IJ). In contrast, we found that after the bacterial population had undergone outgrowth in mature IJs, the advantage for colonization shifted to low‐Lrp expressors: fixed low‐Lrp expressors (M−V+) and wild type (M+V+) exhibited higher average bacterial CFU per IJ than did high‐Lrp (M+V−) or no‐Lrp (M−V−) strains. Further, the bacterial population becomes increasingly low‐Lrp expressing, based on expression of an Lrp‐dependent fluorescent reporter, as IJs age. These data support a model that virulent X. nematophila have a selective advantage and accumulate in aging IJs in advance of exposure to insect hosts in which this phenotype is necessary.
Additional Information
© 2020 Society for Applied Microbiology and John Wiley & Sons Ltd. Issue Online: 20 December 2020; Version of Record online: 03 November 2020; Accepted manuscript online: 19 October 2020; Manuscript accepted: 18 October 2020; Manuscript revised: 03 October 2020; Manuscript received: 15 July 2020. This work was funded by an NSF grant to HGB (IOS – 1353674) and by funds from the University of Tennessee‐Knoxville. Additionally, MC was supported by a UW‐Madison Louis and Elsa Thomsen Wisconsin Distinguished Graduate Fellowship and a Department of Bacteriology Michael Foster Predoctoral Fellowship. The authors thank Dr. Kristen Murfin for training MC in nematode sample preparation and identification of X. nematophila colonization stages.Attached Files
Supplemental Material - emi15286-sup-0001-supinfo.pdf
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Additional details
- Eprint ID
- 106751
- Resolver ID
- CaltechAUTHORS:20201120-074102902
- IOS-1353674
- NSF
- University of Tennessee
- University of Wisconsin-Madison
- Created
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2020-11-20Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field