High Epoxidation Yields of Vegetable Oil Hydrolyzates and Methyl Esters by Selected Fungal Peroxygenases

• Published in: Frontiers in bioengineering and biotechnology Vol. 8; p. 605854
• Main Authors: González-Benjumea, Alejandro, Marques, Gisela, Herold-Majumdar, Owik M., Kiebist, Jan, Scheibner, Katrin, del Río, José C., Martínez, Angel T., Gutiérrez, Ana
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 05.01.2021
• Subjects: Bioengineering and Biotechnology; enzymes; epoxidation; fatty acid methyl esters; peroxygenases; polyunsaturated fatty acids; vegetable oils; fatty acid methyl esters; epoxidation; polyunsaturated fatty acids; enzymes; vegetable oils; complex lipid mixtures; biocatalysis; peroxygenases
• DOI: 10.3389/fbioe.2020.605854
• ISSN: 2296-4185

Epoxides of vegetable oils and free and methylated fatty acids are of interest for several industrial applications. In the present work, refined rapeseed, sunflower, soybean, and linseed oils, with very different profiles of mono- and poly-unsaturated fatty acids, were saponified and transesterified, and the products treated with wild unspecific peroxygenases (UPOs, EC 1.11.2.1) from the ascomycete Chaetomium globosum ( Cgl UPO) and the basidiomycete Marasmius rotula ( Mro UPO), as well as with recombinant UPO of the ascomycete Humicola insolens (r Hin UPO), as an alternative to chemical epoxidation that is non-selective and requires strongly acidic conditions. The three enzymes were able of converting the free fatty acids and the methyl esters from the oils into epoxide derivatives, although significant differences in the oxygenation selectivities were observed between them. While Cgl UPO selectively produced “pure” epoxides (monoepoxides and/or diepoxides), Mro UPO formed also hydroxylated derivatives of these epoxides, especially in the case of the oil hydrolyzates. Hydroxylated derivatives of non-epoxidized unsaturated fatty acids were practically absent in all cases, due to the preference of the three UPOs selected for this study to form the epoxides. Moreover, r Hin UPO, in addition to forming monoepoxides and diepoxides of oleic and linoleic acid (and their methyl esters), respectively, like the other two UPOs, was capable of yielding the triepoxides of α-linolenic acid and its methyl ester. These enzymes appear as promising biocatalysts for the environmentally friendly production of reactive fatty-acid epoxides given their self-sufficient monooxygenase activity with selectivity toward epoxidation, and the ability to epoxidize, not only isolated pure fatty acids, but also complex mixtures from oil hydrolysis or transesterification containing different combinations of unsaturated (and saturated) fatty acids.