Potential of Datura innoxia cell suspension cultures for glucosylating hydroquinone.

The efficiency of glucosylation of hydroquinone by Datura innoxia cell suspension cultures was investigated. The yield of arbutin was 2.4 g/l medium when 10 mM of hydroquinone was added to a suspension culture that was then incubated for 24 h, but the yield decreased at a higher concentration. This decrease, which could not be overcome by changing the growth phase or increasing the cell density used, could be avoided by the repeated addition of a low concentration of hydroquinone over 3 days. This increased the yield of arbutin to 4.2 g/l at the usual cell density and to 7.1 g/l at a high density. The kinetics of this reaction were explained by the Michaelis-Menten formula. The theoretical maximum velocity of the arbutin-forming reaction was estimated as 0.77 mg/h/g. The velocity increased linearly up to a cell density of 300 g/l under standard aeration, the theoretical maximum yield of arbutin being calculated to be 5.5 g/l/day.