Hundreds of antimicrobial peptides create a selective barrier for insect gut symbionts.

The spatial organization of gut microbiota is crucial for the functioning of the gut ecosystem, although the mechanisms that organize gut bacterial communities in microhabitats are only partially understood. The gut of the insect has a characteristic microbiota biogeography with a multispecies community in the anterior midgut and a monospecific bacterial population in the posterior midgut. We show that the posterior midgut region produces massively hundreds of specific antimicrobial peptides (AMPs), the Crypt-specific Cysteine-Rich peptides (CCRs) that have membrane-damaging antimicrobial activity against diverse bacteria but posterior midgut symbionts have elevated resistance.

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

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.

Intercontinental Diversity of Caballeronia Gut Symbionts in the Conifer Pest Bug Leptoglossus occidentalis.

Many stinkbugs in the superfamily Coreoidea (Hemiptera: Heteroptera) develop crypts in the posterior midgut, harboring Caballeronia (Burkholderia) symbionts. These symbionts form a monophyletic group in Burkholderia sensu lato, called the "stinkbug-associated beneficial and environmental (SBE)" group, recently reclassified as the new genus Caballeronia. SBE symbionts are separated into the subclades SBE-α and SBE-β.