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Title: Xenorhabdus nematophila bacteria shift from mutualistic to virulent Lrp‐dependent phenotypes within the receptacles of Steinernema carpocapsae insect‐infective stage nematodes
Summary

Xenorhabdus nematophilabacteria are mutualists ofSteinernema carpocapsaenematodes and pathogens of insects.Xenorhabdus nematophilaexhibits 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 carriesX. nematophilabetween 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 virulentX. nematophilahave a selective advantage and accumulate in aging IJs in advance of exposure to insect hosts in which this phenotype is necessary.

 
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NSF-PAR ID:
10454278
Author(s) / Creator(s):
 ;  
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
Environmental Microbiology
Volume:
22
Issue:
12
ISSN:
1462-2912
Page Range / eLocation ID:
p. 5433-5449
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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