when 1-13c- or 2-13c-enriched fructose was used as the precursor of alginate , enrichment with 13c in the constituent uronic acid monomers of the polysaccharide could only be detected in c-1 or c-2 respectively , indicating that alginate is synthesized in ps . aeruginosa directly from fructose , with the hexose molecule being retained intact ;
C0016745
fructose
C0019494
hexose