Biosynthesis of Cellulose From Culture Media Containing13C-Labeled Glucose as a Carbon Source

13C-Labeled celluloses were biosynthesized by Acetobacter xylinum (IFO 13693) from culture media containing D-[1-13C]glucose, D-[6-13C]glucose, or D-[2-13C]glu-cose as a carbon source with or without addition of ethanol, and their structures were analyzed by 13C NMR spectroscopy. The labeling was mainly found in the original position, that is C-1, C-6 or C-2, in cellulose obtained from D-[1-13C]glucose, D-[6-13C]-glucose or D-[2-13C]glucose, respectively, indicating direct polymerization of introduced glucoses, especially with addition of ethanol in culture medium. Furthermore, C-1 carbons in cellulose obtained from D-[6-13C]glucose, and C-1, C-3 and C-5 carbons in cellulose obtained from D-[2-13C]glucose were labeled. From the analysis of labeling, the mechanism of biosynthesis of cellulose was explained by (1) direct synthesis from glucose, (2) isomerization and rearrangement of trioses formed in the Embden-Meyerhof pathway, Entner-Doudoroff pathway, or pentose cycle, followed by neogenesis of glucose and formation of cellulose, (3) the pentose cycle and (4) neogenesis of glucose from fragments produced in various pathways of glycolysis, followed by formation of cellulose. It is noted that 13C-labeling at C-6 and C-2 carbons in the starting glucoses is well preserved in C-6 and C-1 carbons, and C-1 to C-3 carbons, respectively, in celluloses obtained.