Abstract
<title>Abstract</title> <p> Background <italic>Granulicatella adiacens</italic> , an oral commensal with a poorly described mobilome. Objectives To characterize prophage-like hallmark regions in <italic>G. adiacens</italic> isolates and clarify and compare their genomic architecture and evolutionary signals with potential clinical cargo. Methods Using in silico hallmark-based screening, assessment of nucleotide composition, integration-associated characteristics, prediction of lifestyles, and gene content were performed using Python script with Biopython and databases from the literature. Results Overall, the loci shared similar GC content with pronounced fluctuations and average negative shifts in ∆GC, suggesting mosaic assembly by horizontal gene transfer. All hallmark regions were mobile and had high inedibility, but were poorly inducible. Canonical lytic packaging signatures were absent, suggesting a lack of structural modules. The heterogeneous boundary architecture of att-like repeats with possible prophage-derived islands, but only two loci displayed phage-inducible chromosomal island structures. The relatedness results reflect a shared origin or recent exchange modules. Despite the enrichment of these loci with genes for mobility and replication functions, they were depleted for confidently detectable antimicrobial resistance genes and virulence factors. Discussion The findings suggest that prophage-like islands in <italic>G. adiacens</italic> isolates are mobile and have stable platforms of recombination, contributing to niche adaptation as commensals of the oral cavity. Conclusion Relevant markers remains understudied, especially those associated with endocarditis. Our findings support the incorporation of genomic surveillance of prophages in clinical microbiology pipelines with profiling and screening for modules of integrases for strain relatedness, unjustified phenotypic differences between isolates of near-clones, and lineages with advanced capacities for gene mobilization. </p>