Transposon sequencing reveals the essential gene set and genes enabling gut symbiosis in the insect symbiont Caballeronia insecticola

• Published in: ISME Communications Vol. 4; no. 1; p. ycad001
• Main Authors: Jouan, Romain, Lextrait, Gaëlle, Lachat, Joy, Yokota, Aya, Cossard, Raynald, Naquin, Delphine, Timchenko, Tatiana, Kikuchi, Yoshitomo, Ohbayashi, Tsubasa, Mergaert, Peter
• Format: Journal Article
• Language: English
• Published: England Springer Nature 01-01-2024; Oxford University Press
• Subjects: Animal biology; Bacteriology; Ecology, environment; Genetics; Invertebrate Zoology; Life Sciences; Microbiology and Parasitology; Original; Symbiosis; gut symbiosis; Burkholderia sensu lato; fitness gene; Riptortus pedestris; Tn-seq; genome comparison; Caballeronia insecticola; essential gene
• ISSN: 2730-6151; 2730-6151
• DOI: 10.1093/ismeco/ycad001

is a bacterium belonging to the
genus
, which is able to colonize multiple environments like soils and the gut of the bean bug
. We constructed a saturated
mariner transposon library and revealed by transposon-sequencing that 498 protein-coding genes constitute the essential genome of
for growth in free-living conditions. By comparing essential gene sets of
and seven related
strains, only 120 common genes were identified, indicating that a large part of the essential genome is strain-specific. In order to reproduce specific nutritional conditions that are present in the gut of
, we grew the mutant library in minimal media supplemented with candidate gut nutrients and identified several condition-dependent fitness-defect genes by transposon-sequencing. To validate the robustness of the approach, insertion mutants in six fitness genes were constructed and their growth deficiency in media supplemented with the corresponding nutrient was confirmed. The mutants were further tested for their efficiency in
gut colonization, confirming that gluconeogenic carbon sources, taurine and inositol, are nutrients consumed by the symbiont in the gut. Thus, our study provides insights about specific contributions provided by the insect host to the bacterial symbiont.