Genomic insights from HD0315_2: General features and pathogenic potential.

Background: is the most diverse distributed species of and can cause fatal human infections under rare conditions. However, its pathogenic mechanisms and adaptation ability behind infections remain unclear. Herein, we reported the complete genome sequence of HD0315_2 isolated from the feces of a patient with Crohn's disease. Then, we performed genomic analyses to understand its pathogenic mechanisms and adaptation ability.

Results: The assembly revealed that the HD0315_2 strain carried a circular chromosome of 3.27 Mb and six circular plasmids (19.41 to 139.50 kb). The phylogenomic analysis assigned the HD0315_2 strain as and reclassified some previously non- strains into this clade. The general genomic features showed that this species harbored a flexible genomic pool characterized by variable genome length and multiple plasmids. Then, the HD0315_2 strain was predicted as a human pathogen with high probability, and LIPI-1 virulence proteins were identified on its genome. Besides, abundant antibiotics/metal/stress resistant genes, such as , and , were carried by either the genome or the plasmids. Furthermore, we proposed that transposase-directed horizontal gene transfer was responsible for the distribution of multiple copies of the gene in the plasmids.

Conclusion: The flexible genomic pool of encodes abundant functions for antimicrobial or oxidative stress resistance, helping it successfully inhabit and adapt to diverse environments. Moreover, HD0315_2 might infect hosts a LIPI-1-like cycle, with the help of a plasmid expressing the Hin DNA invertase to evade host immune responses.