Yellow pigment of Gardenia jasminoides was converted into new pigment by whole-cell biotransformation of thirteen different microbial species. The color value of the biotransformed pigment, which was produced by Streptococcus mutans MK-34, was higher than those of other biotransformed pigments. The biotransformed pigment produced by S. mutans MK-34 dispalyed an characteristic absorption peak at 588 nm and the absorption value increased during the incubation in a jar fermentor. The effects of light and temperature $(60^{circ}C)$ on storage stability of the biotransformed pigment were investigated. As a result, the biotransformed pigments produced by Streptococcus mutans and Bacillus subtilis were more stable than Gardenia jasminoides yellow pigment during storage.