Abstract
Arbutin is a whitening agent, which is extracted from plants and the yield is quite low. A more economical and environmental friendly way is to synthesize arbutin by structural modification of hydroquinone via glycosylation(biotransformation). Presently, Kurosu and coworkers(2002) have successfully synthesized arbutin by glycosylation of hydroquinone with maltose as a glucosyl donor using lyophilized cells of Xanthomonas campestris WU- 9701 as the biocatalyst. However, a fast and simple screening method for microorganisms which have catalytic activity of glycosylation has not been established up till now. So, the objective of our study was to set up a easy and efficient screening method for obtaining mutated strains that have high hydroquinone-glycosylation activity. Our screening method was based on the fact that hydroquinone solution was more light-sensitive than arbutin. We selected the mutated strains from 96-well plates after reaction and light exposure and used the color difference as the screening index. After five rounds of mutation, repeated screening and optimization of reaction conditions, we obtained a high activity strain, Xanthomonas campestris 5H10, which has a conversion of about 85%.