Whole cells of mutated Xanthomonas campestris were successfully used as a biocatalyst for the glucosylation of kojic acid. Suitable carbon and nitrogen sources and the pH for the cultivation of the mutated cells at 30 degrees C were identified for maximum conversion. Using 0.1 g of the cells, 80% conversion was obtained after 28 h at 30 degrees C and by using maltose as the acyl donor at a molar ratio of 1:8. Under the same conditions, the use of wild type cells resulted in 13% conversion only. ID NMR and 21) shift-correlated NMR (H-1 x H-1-COSY, H-1 x C-13-COSY) analysis showed that the product was kojic acid 7-o-alpha-D-glucopyranoside. (c) 2006 Elsevier Inc. All rights reserved.