Comprehensive analysis of cell-associated fatty acids in <i>Bifidobacterium</i> strains

Bifidobacteria are Gram-positive, anaerobic bacteria known for their health-promoting effects. However, a comprehensive analysis of middle- and long-chain fatty acids in bifidobacteria remains elusive. This study aimed to evaluate fatty acid accumulation among 43 strains covering 40 species/subspecies, and to elucidate interspecies and interstrain variations. Analysis of their cell-associated fatty acids revealed significant differences in total fatty acid levels. Bifidobacterium thermacidophilum and related species exhibited notably high accumulation of multiple fatty acids (eg decanoic acid, cis-7-C16:1). Among Bifidobacterium breve strains, M-16V produced significantly more cis-7-C16:1 than the others. Additionally, a homology analysis targeting cyclopropane fatty acid synthase was performed to determine the genetic basis of cis-9,10-methyleneoctadecanoic acid (cyclo-C19:0) production. Only strains possessing the homolog produced cyclo-C19:0. These results highlight substantial variation in fatty acid accumulation among bifidobacteria, which could influence their probiotic functionalities. This study provides a foundation for future research on the health benefits of bifidobacterial fatty acid profiles.