Genomic evidence of ecological flexibility and cross-niche CRISPR spacerome targeting phage–plasmid hybrids in Latilactobacillus curvatus

BACKGROUND: Latilactobacillus curvatus is a lactic acid bacterium with a remarkable ability to persist in diverse niches, including fermented foods and gut. Despite its industrial and potential probiotic relevance, the genomic underpinnings of its cross-niche adaptability remain poorly characterized. METHODS: We conducted a species-contextualized comparative genomic analysis of 53 L. curvatus strains from food and gut isolates. This analysis integrated pangenome structure, metabolic repertoire, CRISPR-Cas immunity profiles, and mobilome analysis. Additionally, binding mode predictions and dynamics simulations were used to evaluate the theoretical binding energies of bacteriocins to the BamA target. RESULTS: Phylogenomics revealed a polyphyletic population structure, indicating that long-term evolution is not strictly niche-specific. In contrast, genome-wide similarity showed clustering by isolation source, highlighting horizontal gene transfer (HGT) as a plausible contributor to niche adaptation. We identified a highly active mobilome, encompassing diverse plasmids, IS elements, and multiple intact prophages, reflecting high genomic plasticity characteristic of a multihabitat lifestyle. CRISPR-Cas systems were widespread, and analysis of 2,029 spacers revealed a broad immune repertoire targeting mobile genetic elements represented in fermented food, gut, and environmental datasets. We also identified spacer matches to phage-plasmid hybrid-like elements, highlighting the diversity of mobile genetic elements associated with the L. curvatus spacerome. CONCLUSION: Our study reveals genomic features consistent with ecological flexibility in L. curvatus, including high genomic plasticity and a broad CRISPR spacer repertoire. Rather than demonstrating strict niche-specific evolution or a causal mechanism for cross-niche persistence, these findings support the hypothesis that this species has experienced diverse interactions with mobile genetic elements across multiple ecological contexts.