Whole Genome Sequence Analysis of Bifidobacterium animalis subsp. lactis KL101 and Comparative Genomics with BB12

<italic>Bifidobacterium </italic>species is a prominent bacterium in the human gut, particularly in infants, where it plays a vital role in maintaining gut health. The whole genome sequence of <italic>B. animalis</italic> subsp. <italic>lactis</italic> KL101 (KL101), isolated from infant feces, exhibits a compact structure with a genome size of approximately 1.92 Mbp comprising 1,555 coding sequences. Key chromosomal characteristics are genes encoding bile salt hydrolase and the thioredoxin system, which contribute to bile acid resistance and the oxidative stress response, respectively. Moreover, the genome has a significant number of genes that play a role in carbohydrate metabolism, supporting its probiotic functions. The comparative genomic analysis of the KL101 strain, in comparison to the well-known BB12 strain (<italic>B. animalis</italic> subsp. <italic>lactis</italic> BB12), reveals unique and similar characteristics. Although both strains have a similar GC content, KL101 exhibits unique genomic characteristics that may contribute to its specific adaptations in the infant gut. The results demonstrate that KL101 is highly adapted, with a genome specifically designed to efficiently process carbohydrates, withstand stress, and interact with its host. These findings enhance our understanding of KL101, supporting its potential applications in dietary supplements and health foods aimed at improving gut health.