Comparative genomics of Bifidobacterium longum strains identifies genes relevant for human milk oligosaccharides utilization
Riccardo G. LoCascio1, David A. Sela1, Prerak Desai2, Samara L. Freeman3, Bart Weimer2, Carlito B. Lebrilla4, J. Bruce German3, and David A. Mills1: 1Dept. of Viticulture & Enology, 3Dept. of Food Science & Technology, 4Chemistry Dept., 1, 3 Robert Mondavi Institute for Wine and Food Science, University of California – Davis, Davis, CA 95616, USA. 2Center for Integrated Biosystems, Utah State University, Logan, 84321 UT, USA.
Abstract: Human breast milk has a profound effect on the microbial diversity of the developing infant gastrointestinal tract. Human Milk Oligosaccharides are believed to provide protection against pathogens and prebiotic enrichment of beneficial commensals such as bifidobacteria. B. longum biovar infantis ATCC15697, a microorganism commonly present in the feces of breast-fed infants, preferentially consumes four milk oligosaccharides representing nearly 70% of all HMOs present in milk This suggests that HMOs are a class of bioactive milk molecules capable of enriching the growth of specific bacterial populations in the gut of breastfeeding infants. The underlying mechanism(s) regulating bioactive components in milk and a protective microflora rich in bifidobacteria is yet to be elucidated. The purpose of this study was to identify a core set of genes among bifidobacteria strains that exhibit robust growth on HMOs. By combining Microarray-based Comparative Genomic Hybridization analyses with high throughput glycomics of HMO consumption, we have begun to identify a core set of genes, relevant for HMO utilization, that are shared across the B. infantis clade. These findings will help elucidate how bioactive milk oligosaccharides ultimately lead to an enrichment of bifidobacteria in the microflora of exclusively breast-fed infants.