BIOSYNTHESIS OF CELLULOSE FROM CULTURE MEDIA CONTAINING C-13-LABELED GLUCOSE AS A CARBON SOURCE

C-13-Labeled celluloses were biosynthesized by Acetobacter xylinum (IF O 13693) from culture media containing D-[1-C-13]glucose, D-[6-C-13]gl ucose, or D-[2-C-13]glucose as a carbon source with or without additio n of ethanol, and their structures were analyzed by C-13 NMR spectrosc opy. The labeling was mainly found in the original position, that is C -1, C-6 or C-2, in cellulose obtained from D-[1-C-13]glucose, D-[6-C-1 3]glucose or D-[2-C-13]glucose, respectively, indicating direct polyme rization of introduced glucoses, especially with addition of ethanol i n culture medium. Furthermore, C-1 carbons in cellulose obtained from D-[6-C-13]glucose, and C-1, C-3 and C-5 carbons in cellulose obtained from D-[2-C-13]glucose were labeled. From the analysis of labeling, th e mechanism of biosynthesis of cellulose was explained by (1) direct s ynthesis from glucose, (2) isomerization and rearrangement of trioses formed in the Embden-Meyerhof pathway, Entner-Doudoroff pathway, or pe ntose cycle, followed by neogenesis of glucose and formation of cellul ose, (3) the pentose cycle and (4) neogenesis of glucose from fragment s produced in various pathways of glycolysis, followed by formation of cellulose. It is noted that C-13-labeling at C-6 and C-2 carbons in t he starting glucoses is well preserved in C-6 and C-1 carbons, and C-1 to C-3 carbons, respectively, in celluloses obtained.