Bioconversion ofN-Butylglucamine to 6-Deoxy-6-butylamino Sorbose byGluconobacteroxydans

Abstract

Gluconobacter oxydans has the unique ability to regioselectively and rapidly oxidize sorbitol and other erythro saccharides. In this report a new process is described by which N-butylglucamine is regioselectively oxidized by the organism. A large-scale process is described by which N-butylglucamine can be converted to an intermediate (6-deoxy-6-butylaminosorbose) which can be readily converted to N-butyldeoxynojirimycin by catalytic hydrogenation. The primary process variables of temperature, pH, and added acids and salts were investigated in laboratory bioreactors. Since degradation of the sorbose product was rapid above room temperature, significant enhancement of the selectivity was achieved by lowering the temperature at which the bioconversion was run. The optimum temperature for this conversion was 12−15 °C. The pH maximum of the bioconversion was 5.5−6.0. However, the small gain in rate relative to pH 5.0 was at least offset by the increase in degradation of the product at the higher pH. Nitrate salts of N-butylglucamine could replace chloride salts, but sulfate, acetate, and phosphate salts could not. Sulfate in particular led to inhibition of the conversion, while phosphate and acetate led to increased degradation. At temperatures in the range of 12−15 °C, pH of around 5.0 and substrate concentrations of 0.2 M, Gluconobacter oxydans catalyzed bioconversion to 6-deoxy-6-butylaminosorbose with yields approaching 95%. These conditions were used to scale this process to 5500-L scale.

Understanding and Improving NADPH‐Dependent Reactions by Nongrowing Escherichia coli Cells

“…In their very useful summary of fine chemicals that have been produced commercially in biotransformations, Straathof et al listed data for three enzymatic oxidations, all of which employed whole cells (3). One of these examples, the oxidation of N ‐butylglucamine by nongrowing Gluconobacter oxid ans cells reported by Landis et al (43) was exceptionally efficient compared to the other two, which are more typical for this type of bioconversion (space−time yields of 0.003 and 0.002 g/L·h and final product titers of 1.0 and 0.4 g/L, respectively) (44, 45). We carried out the Baeyer−Villiger oxidation of cyclohexanone with a space‐time yield of 0.38 g/L·h to afford 9.1 g/L product using a biocatalyst:substrate ratio (g/g) of 0.63.…”

Applied Microbiology

“…The reaction product is (3S, 4R, 5S)-1, 3, 4, 5-tetrahydroxy -6 -(alkylamino) hexan-2-one; a sorbose derivative is a key intermediate in the synthesis of oral α-glucosidase inhibitors (Landis et al 2002 ). Oxidoreductases are employed using whole cells due to their dependence on cofactors that need to be regenerated.…”

Microbial Enzymes and Their Industrial Applications

“…Whole cells of Gluconobacter suboxydans are responsible for the regio-selective oxidation of N-protected-1-amino-D -sorbitol. The reaction product is (3S, 4R, 5S)-1, 3, 4, 5-tetrahydroxy -6 -(alkylamino) hexan-2-one; a sorbose derivative is a key intermediate in the synthesis of oral α-glucosidase inhibitors (Landis et al 2002 ). Similarly, Streptomyces species has been used by Bristol-Myers Squibb to carry out biotransformation of compactin to pravastin (sodium (3R,5R)-3,5-dihydroxy-7-((1S, 2S, 6S, 8S, 8aR)-6-hydroxyl-2-methyl-8-((S)-2-methylbutanoyloxy) -1, 2, 6, 7, 8, 8a-hexahydronaphthalen-1-yl) heptanoate).…”