Full-Length Gene Sequencing Reveals Two Distinct Bacterial Communities in Black-Legged Ticks Expanding Into Canada
Researchers used Oxford Nanopore full-length 16S rRNA gene sequencing to characterize the microbiome of Ixodes scapularis black-legged ticks collected in Nova Scotia, Canada, distinguishing between tick-adapted bacteria and environmentally acquired bacteria. The study comes as I. scapularis — the primary vector of Lyme disease — is rapidly expanding northward into Canada due to climate change. The findings suggest that environmentally derived bacteria in tick microbiomes are not mere contamination, which has implications for how tick microbiome data is collected and interpreted across surveillance studies.
A preprint study posted to bioRxiv applied full-length Oxford Nanopore 16S ribosomal RNA gene amplicon sequencing to profile the microbiome of Ixodes scapularis, the black-legged tick, collected in Nova Scotia, Canada. The research explicitly distinguished between two ecological classes of bacteria: tick-adapted organisms such as endosymbionts and pathogens like Borrelia burgdorferi, and environmentally acquired bacteria originating from soil, vegetation, or vertebrate hosts. The study found that 'environmental dominance strength' — the degree to which environmental bacteria shape the microbiome signal — differs between these two classes, and that this environmental signal is not simply stochastic background noise or contamination. This is methodologically significant because amplicon sequencing of tick DNA is increasingly used in public health surveillance to monitor B. burgdorferi prevalence, and inconsistent handling of environmental bacterial signals can complicate cross-study comparisons. The authors call for paired soil microbiome sampling from tick collection sites to determine whether environmental dominance patterns shift with seasons and local microbial populations. The work is particularly timely given the ongoing northward range expansion of I. scapularis driven by climate change, which is bringing Lyme disease risk to previously unaffected Canadian populations.
What's missing
As a preprint, this study has not yet undergone peer review, so methods and conclusions should be interpreted with caution. The authors themselves note that paired soil microbiome data — needed to confirm whether environmental dominance tracks seasonal and local microbial variation — were not collected in this study, leaving a key mechanistic question open.
What different sources said
- bioRxivCenter
Full-length 16S ribosomal RNA gene sequencing reveals dynamics of tick-adapted and environmentally derived bacteria in the microbiome of the black-legged tick, Ixodes scapularis in Nova Scotia, Canada
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