Streptococcus pneumoniae Can Utilize Multiple Sources of Hyaluronic Acid for Growth

Abstract

ABSTRACTThe mechanisms by whichStreptococcus pneumoniaeobtains carbohydrates for growth during airway colonization remain to be elucidated. The low concentration of free carbohydrates in the normal human airway suggests that pneumococci must utilize complex glycan structures for growth. The glycosaminoglycan hyaluronic acid is present on the apical surface of airway epithelial cells. As pneumococci express a hyaluronate lyase (Hyl) that cleaves hyaluronic acid into disaccharides, we hypothesized that during colonization pneumococci utilize the released carbohydrates for growth. Hyaluronic acid supported significant pneumococcal growth in anhyl-dependent manner. A phosphoenolpyruvate-dependent phosphotransferase system (PTS) and an unsaturated glucuronyl hydrolase (Ugl) encoded downstream ofhylare also essential for growth on hyaluronic acid. This genomic arrangement is present in several other organisms, suggesting conservation of the utilization mechanism between species.In vivoexperiments support the hypothesis thatS. pneumoniaeutilizes hyaluronic acid as a carbon source during colonization. We also demonstrate that pneumococci can utilize the hyaluronic acid capsule of other bacterial species for growth, suggesting an alternative carbohydrate source for pneumococcal growth. Together, these data support a novel function for pneumococcal degradation of hyaluronic acidin vivoand provide mechanistic details of growth on this glycosaminoglycan.