earticle

영어

Arabinans can be synergistically degraded into L-arabinose and arabinooligosaccharides (AOS) by the actions of exo-arabinofuranosidase (AF) and endo-arabinanase (ABN). Bifidobacterium spp., the well-known probiotic bacteria, were reported to utilize linear AOS as the prebiotic carbohydrates. Two different endo-arabinanase genes were previously found and cloned from the genome of Bifidobacterium longum subsp. suis DSM 20211. In this study, the modes of action for both endo-arabinanases, BflsABN-B1 and B2, were comparatively characterized, and their gene cluster was analyzed in detail. The gene cluster analysis revealed that the corresponding contig 11 of Bf. longum subsp. suis includes several putative exo-acting AF genes, the ABC transporter-related genes, ATP-binding protein genes, as well as both ABNs-B. According to the gene cluster analysis, the extracellular BflsABN-B1 hydrolyzes arabinan polymers to the short chain AOS, which are imported into the cell membrane through the ABC transporters. Within a cell, AOS can be hydrolyzed into L-arabinose by an intracellular BflsABN-B2 and various exo-AFs. These results proposed the hypothetical enzymatic system for the arabinan utilization in Bf. longum subsp. suis.