Generation of norisoprenoid flavors from carotenoids by fungal peroxidases.

To biotechnologically produce norisoprenoid flavor compounds, two extracellular peroxidases (MsP1 and MsP2) capable of degrading carotenoids were isolated from the culture supernatants of the basidiomycete Marasmius scorodonius (garlic mushroom). The encoding genes were cloned from genomic DNA and cDNA libraries, and databank homology searches identified MsP1 and MsP2 as members of the so-called "DyP-type" peroxidase family. Wild type enzymes and recombinant peroxidases expressed in Escherichia coli were employed for the release of norisoprenoids from various terpenoid precursor molecules. Carotenes, xanthophylls, and apocarotenals were subjected to the enzymatic degradation. Released volatile products were characterized by GC-FID and GC-MS, whereas nonvolatile breakdown products were analyzed by means of HPLC-DAD and HPLC-MS. C13 norisoprenoids together with C10 products proved to be the main volatile degradation products in each case.