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. Author manuscript; available in PMC: 2015 Jul 9.
Published in final edited form as: Cell Host Microbe. 2014 Jul 9;16(1):55–67. doi: 10.1016/j.chom.2014.06.005

Figure 7. Nutrient-poor conditions on the human mucosal surface favor growth of sialic acid catabolizing pneumococci.

Figure 7

(A) Bacteria of the indicated genotypes were grown for 8 hrs in mixed inocula in tryptic soy nutrient broth, or in nutrient-limited human nasal airway surface fluid (hNASF). Aliquots were plated at the beginning and end of the growth period, and colonies patched onto antibiotic-selective media to determine the relative advantage of sialic acid catabolism in vivo and calculate competitive indices. CI > 1 indicates WT outcompeted the indicated mutant strain. (B) Total sialic acid in the growth media used in A was measured by thiobarbituric acid assay after acid hydrolysis. (C) WT (solid bars) and ΔsatABC (open bars) pneumococci were grown for 24 hrs in chemically defined medium with the indicated concentrations of sialic acid as the sole carbon source. Data show fold-growth compared to inoculum. Data are represented as mean +/− SD. n.s. = not significant, * = p < 0.05, ** = p < 0.01, *** = p < 0.001. Experiments were performed at least twice.