PT  - JOURNAL ARTICLE
AU  - Benjamin D. Ross
AU  - Beth Hayes
AU  - Matthew C. Radey
AU  - Xia Lee
AU  - Tanya Josek
AU  - Jenna Bjork
AU  - David Neitzel
AU  - Susan Paskewitz
AU  - Seemay Chou
AU  - Joseph D. Mougous
TI  - <em>Ixodes scapularis</em> does not harbor a stable midgut microbiome
AID  - 10.1101/198267
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 198267
4099  - http://biorxiv.org/content/early/2017/10/04/198267.short
4100  - http://biorxiv.org/content/early/2017/10/04/198267.full
AB  - Hard ticks of the order Ixodidae serve as vectors for numerous human pathogens, including the causative agent of Lyme Disease Borrelia burgdorferi. Tick-associated microbes can influence pathogen colonization, offering the potential to inhibit disease transmission through engineering of the tick microbiota. Here, we investigate whether B. burgdorferi encounters abundant bacteria within the midgut of wild adult Ixodes scapularis, its primary vector. Through the use of controlled sequencing methods and confocal microscopy, we find that the majority of field-collected adult I. scapularis harbor limited internal microbial communities that are dominated by endosymbionts. A minority of I. scapularis ticks harbor abundant midgut bacteria and lack B. burgdorferi. We find that the lack of a stable resident midgut microbiota is not restricted to I. scapularis since extension of our studies to I. pacificus, Amblyomma maculatum, and Dermacentor spp showed similar patterns. Finally, bioinformatic examination of the B. burgdorferi genome revealed the absence of genes encoding known interbacterial interaction pathways, a feature unique to the Borrelia genus within the phylum Spirochaetes. Our results suggest that reduced selective pressure from limited microbial populations within ticks may have facilitated the evolutionary loss of genes encoding interbacterial competition pathways from Borrelia.