2-Keto-L-gulonic Acid Fermentation

Abstract

A number of bacterial strains from type culture collections and natural sources were examined in their metabolic characteristics toward sorbitol and L-sorbose.Paper chromatographic analyses of sorbitol and L-sorbose metabolites obtained from the cultures of various bacteria revealed that the organisms producing 2-keto-L-gulonic acid from sorbitol were merely found in the genera Acetobacter, Gluconobacter and Pseudomonas, whereas those producing the acid from L-sorbose were distributed in the twelve genera of bacteria: Acetobacter, Alcaligenes, Aerobacter, Acotobacter, Bacillus, Escherichia, Gluconobacter, Klebsiella, Micrococcus, Pseudomonas, Serratia and Xanthomonas.G. melanogenus, which was characterized by excellent production of 2-keto-L-gu Ionic acid from sorbitol, also formed several other sugars and sugar acids as the sorbitol metabolites. These compounds were identified to be D-fructose, L-sorbose, D-mannonic acid, L-idonic acid, 2-keto-D-gluconic acid and 5-keto-D-mannonie acid, respectively, by means of two-dimensional paper chromatography.Bacteria producing 2-keto-L-gulonic acid from sorbitol were usually isolated from fruits but not from soil.

Biotechnical modification of carbohydrates

“…In this pathway sorbose is further dehydrogenated over sorbosone to 2-KLG. Gluconobacter melanogenus was found to be the best producer of 2-KLG from screening experiments [21]. Another way for converting sorbose into 2-KLG passes over L-idose and L-idonic acid, as this pathway is found in Pseudomonas strains and others [221.…”

Direct fermentation of 2‐keto‐l‐gulonic acid in recombinant Gluconobacter oxydans

“…The practical yield of the process from D-glucose to L-ascorbic acid is thought to be around 50% with the recent advances in chemical engineering (Boudrant, 1990). To improve the yield of 2-KLGA, direct microbial processes to 2-KLGA have been tried (Anderson et al, 1985;Grindley et al, 1988;Hoshino et al, 1990;Isono et al, 1968;Shinjoh et al, 1995;Soneyama et al, 1982;Sugisawa et al, 1990;Sugisawa et al, 1991); however, the yield of 2-KLGA did not exceed the Reichstein method. Our approach was to construct a recombinant Gluconobacter strain that directly ferments 2-KLGA from D-sorbitol in high yield.…”

Metabolism ofL-sorbose by enzymes fromGluconobacter melanogenus IFO 3293

“…The microbial conversion of L-sorbose to 2-keto-L-gulonic acid has been extensively studied (Isono et al, 1968;Kanzaki & Okazaki, 1970;Kitamura & Perlman, 1975;Tengerdy, 1961;and Tsukada & Perlman, 1972 a b c;Makover et al, 1975). As a result 3 metabolic pathways for metabolism have been proposed: I) Tengerdy (1961) has proposed the direct oxidation at the C-I position by Pseudomonas species;…”