Comparative Genomics and In Silico Evaluation of Genes Related to the Probiotic Potential of Bifidobacterium breve 1101A

Bifidobacterium breve is among the first microorganisms colonizing the intestinal tract in humans and is a predominant species in the gut microbiota of newborns and children. This bacterium is widely used in the probiotic industry due to its capacity to improve host health. The search for new targets with probiotic properties is an increasing trend with the help of next-generation sequencing as they facilitate the characterization of the bacterial features. B. breve 1101A was isolated from the faeces of healthy children in Brazil and therefore could play a protective role in the gut. To investigate the beneficial properties of this strain, the present study performed a comprehensive characterization of the genetic features involved in the bacterium resistance and adaptation to gastrointestinal conditions, production of nutrients, and immunomodulatory compounds. Furthermore, this study carried out the prediction of genomic elements (plasmids, prophages, CRISPR-Cas systems, insertion sequences, genomic islands, antibiotic resistance genes) to evaluate the safety of B. breve 1101A. A comparative genomics approach using 45 B. breve complete genomes based on pangenome and phylogenomic analysis was also performed to identify specific genes in B. breve 1101A. The prediction of genetic elements, possibly safety-related, did not detect plasmids, but only one incomplete prophage, two non-functional CRISPR systems, and seven genomic islands. Additionally, three antibiotic resistance genes were identified: ileS (resistance to mupirocin), rpoB, and erm(X). In the comparative genomic analysis, the pangenome was revealed to be open, and B. breve 1101A presented 63 unique genes associated with several processes, such as transmembrane transport, membrane components, DNA processes, and carbohydrate metabolism. In conclusion, B. breve 1101A is potentially safe and well-adapted for intestinal disorder therapeutics, although the role of its unique genetic repertoire needs further investigation.