Illumina-Based Metagenomic Insights into the Gut Microbiome of Amblyomma helvolum (Koch, 1844) Parasitizing Xenochrophis trianguligerus from Great Nicobar Island, India.

During a faunal survey in Great Nicobar Island, we collected four Amblyomma helvolum ticks infesting the snake Xenochrophis trianguligerus and processed for gut-metagenomic analysis using Illumina paired-end sequencing. A total of 8.7 million high-quality reads were generated, revealing that the gut microbiome was dominated by Bacteria (∼99.9%), primarily represented by Proteobacteria (∼95.7%), followed by minor fractions of Firmicutes, Actinobacteria, and Bacteroidetes. The predominant bacterial families were Alcaligenaceae, Bradyrhizobiaceae, Boseaceae, and Rickettsiaceae, with Achromobacter xylosoxidans emerging as the most abundant species (∼30% of total reads). Species-level analyses revealed a complex microbial community dominated by Achromobacter, Brevibacillus, Stutzerimonas, and Aeromicrobium. Several putative opportunistic pathogens were detected, including Myroides sp., Sphingobacterium sp., Stutzerimonas stutzeri, Cutibacterium acnes, Mycobacterium abscessus, Staphylococcus hominis, Achromobacter xylosoxidans, and Pseudomonas otitidis. This study represents the first metagenomic characterization of A. helvolum from India and provides baseline data on reptile-tick-associated microbial diversity from Great Nicobar Island. The findings underscore the importance of molecular surveillance in remote ecosystems and highlight the potential of reptile ticks as reservoirs of opportunistic and zoonotic bacteria.