FORMATION OF 2-HYDROXY-4-METHYLPENTANOIC ACID FROM L-LEUCINE BY CLOSTRIDIUM-BUTYRICUM

Five Clostridium butyricum strains of different origin were grown in t rypticase-yeast extract-hemin medium with or without D-glucose (TGYH o r TYH medium, respectively) and in a synthetic basal medium with D-glu cose (BMG medium). 2-Hydroxy-4-methylpentanoic acid was detected by ga s chromatography-mass spectrometry (GC-MS) for the five strains whethe r grown in TGYH or TYH medium (270 or 170 mu M, respectively). In BMG medium supplemented with L-leucine (10 mM), the concentration of this metabolite was strongly increased (2.8 mM versus 10 mu M in the contro l). After culture in TGYH or TYH medium supplemented with L-(methyl-H- 2(3))leucine, 2-hydroxy-4-([H-2(3)]methyl)pentanoic acid was detected by GC-MS. This observation demonstrates that C. butyricum is able to c onvert L-leucine into the corresponding 2-hydroxy acid and opens a new aspect in the study of C. butyricum metabolism.