(2R,3R,4S,5S)-2,3,4,5-tetrahydroxyhexanal → L-Rhamnitol

Beteiligte Stoffe

Reaktionsschritte

In the presence of the Raney-nickel catalyst, L-rhamnose (10 w/v %) was completely reduced at a temperature of 50° C. and a pressure of 1.2 MPa, to produce 6-deoxy L-mannitol. Using the resulting 6-deoxy L-mannitol as a substrate, 6-deoxy L-fructose was produced. A freshly separated Enterobacter sp. 230S was used for selectively oxidizing the carbon in 6-deoxy L-mannitol at position 2 to prepare 6-deoxy L-fructose. The microorganism was cultured in a mineral salt-added culture medium supplemented with D-sorbitol (0.8 w/v %) and glycerol (0.2 w/v %) under agitation at a temperature of 30° C. and 300 rpm, for 24 hours. The culture was centrifuged at 12,000 rpm for 30 minutes, to harvest the bacterial cells, which were then washed twice with 50 mM Tris-HCl buffer (pH 10). The washed bacterial cells were suspended in the same buffer for use in converting 6-deoxy L-mannitol to 6-deoxy L-fructose. The reaction was done in various substrate concentrations in a 5-liter bioreactor (ABLE DPL-2, Japan), using the bacterial cells of OD600=40, a handling volume of 0.5 liter, an agitation speed of 200 rpm, an air flow rate of 0.2 liters/min and a temperature of 30° C.

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