Isolation of bacterial strains, which hydrolyze glycyrrhizin and produce glycyrrhezic acid, from soil.

We isolated eight bacterial strains which could hydrolyze glycyrrhizin to glycyrrhezic acid. The bacterial strains were identified as three strains of Pseudomonas saccharophila, two of Plesiomonas sp., one of Pseudomonas stutzeri, one of Klebsiella pneumoniae subsp. ozaenae and one of Kluyvera ascorbata. Their capacity for the conversion of glycyrrhizin to glycyrrhezic acid was assayed by high performance liquid chromatography. P. saccharophila 11 was the most effective among the eight strains. Then, beta-glucuronidase, which is responsible for hydrolysis of glycyrrhizin, activity was assayed with p-nitrophenyl-beta-D-glucuronide as a substrate. P. saccharophila 11 showed the highest beta-glucuronidase activity among the eight strains. This indicates that P. saccharophila 11 may be useful for production of glycyrrhezic acid from glycyrrhizin by industrial fermentation.