Biosynthesis of curdlan from culture media containing 13C-labeled glucose as the carbon source

Carbohydrate cycling in micro-organisms: what can13C-NMR tell us?

“…Breakdown of [2‐ 13 C]glucose via the oxidative steps of the pathway forms [1‐ 13 C]ribulose‐5‐phosphate, which, in turn, forms hexose‐phosphates labelled at C1 and/or C3 in the forward reactions (as above). Such labelling patterns were reported for a number of polysaccharide‐producing organisms utilising the PP and ED pathways [41–45,51,52], including the two Rhizobiaceae mentioned above. Carbohydrate metabolism in these species will be discussed in more detail later in this review ().…”

“…By developing a statistical analysis of the coupling figures observed in the 1D NMR spectra of cellulose units and mathematical modelling, Gagnaire and Taravel [52] evaluated that 30% of the total units derived from the exogenous glucose were processed through triose‐phosphate cycling, whereas 26% were processed through PP cycling. Their results were later confirmed by a monolabelling approach [41,42], where [2‐ 13 C]‐ and [4‐ 13 C]glucose were used in addition to [1‐ 13 C]‐ and [6‐ 13 C]glucose. Some quantitative differences exist between the two studies.…”

“…Therefore triose‐phosphate cycling may be expected to occur in situations where gluconeogenesis predominates rather than glycolysis. Clear isotopic evidence for triose‐phosphate cycling through the PP pathway under glycolytic conditions was nonetheless obtained in micro‐organisms also utilising the ED pathway [41–43,52] and will be detailed in . Operation of the cycle in EMP‐utilising organisms is more difficult to evaluate because triose‐phosphate cycling may occur simultaneously via the EMP pathway (see Fig.…”

“…8) was obtained from studies of poly‐ or oligosaccharide biosynthesis – curdlan in Agrobacterium sp. [41,42] and β‐glucans and succinoglycan in S. meliloti [43], using a monolabelling approach. These polysaccharides are made of glucose (curdlan, β‐glucans) or glucose+galactose (succinoglycan) and derive metabolically from glucose‐6‐phosphate.…”

Metabolic13C-Labeling of An Antitumor (1→3)-β-D-Glucan, SSG, fromSclerotinia sclerotiorumIFO 9395

“…11 17) As to (1-+ 3)-f3-o-glucan, only the biosynthesis pathway of curdlan, a linear (1-+ 3)-f3-o-g1ucan, has been reported. 18 ) In this paper, we report the glucose use of the mycelium to produce SSG by using two different culture conditions, in which production of SSG is high and low, assessed by using 13C-nuclear magnetic resonance spectroscopy. Preparation of 13C-SSG.…”