Catabolism of hamamelose. The anaerobic dissimilation of D-hamamelose by Kluyvera citrophila 627.

Abstract

Hamamelose (2‐C‐hydroxymethyl‐d‐ribose) is a common sugar of green land plants. However, until now, all experiments failed to show dissimilation of this sugar by its producers or by soil microorganisms. For investigation of its biological degradation, microorganisms were used which had been isolated from plant material (leaves of Primula clusiana Tausch). These microorganisms belong to the Enterobacteriaceae and are almost identical to those described by Asai et al. (1956, 1962) as Kluyvera citrophila. They differ from the ATCC strains of this organism by their ability to grow on hamamelose.Isotope studies using 14C‐labelled hamamelose and glucose (for comparison) as substrates were carried out to elucidate the biochemical route of hamamelose catabolism. This degradation leads to CO2 under aerobic conditions and to lactate, succinate, formate, acetate and ethanol under anaerobic ones. Glucose dissimilation proceeds via glycolysis and leads to the same end‐products. As intermediates of the biological degradation of hamamelose, hamamelose 21‐phosphate, fructose 1‐phosphate, fructose 1, 6‐bisphosphate and phosphoglycerate were identified. Thus the biochemical route of hamamelose dissimilation appears to be rather similar to glycolysis. The following sequence is proposed: hamamelose → hamamelose 21‐phosphate → fructose 1‐phosphate → fructose 1, 6‐bisphosphate → phosphoglycerate → pyruvate → volatile end‐products. Differences from the glycolytic pathway occur at step 2 in which there is a rearrangement of the carbon skeleton and at step 3, in which fructose 1‐phosphate instead of fructose 6‐phosphate has to be phosphorylated.