Characterization of Novel Ribbed Mussel (Geukensia demissa) Enzymes for Lignin Deconstruction

A novel lignin-digesting enzyme has been identified within ribbed mussels (Geukensia demissa) protein extracts. Enzymatic activity is demonstrated through the use of several model lignin compounds (2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid, 2,6-dimethoxyphenol, veratryl alcohol, and guaiacol), as well as actual lignin isolated from biomasses (lignin alkali, softwood, oakwood, and hardwood). Also, a 3,5-dinitrosalicylic acid assay was used for the enzymatic activity of the extracted proteins from the mussel against lignin. For all assays, a positive relationship between the amount of crude mussel protein extract and lignin-modifying peroxidase activity was observed. Extracts from digestive tissues of ribbed mussels contained more lignin peroxidase activity than extracts from nondigestive tissue. This identified enzymatic activity may offer a new area of investigation in biofuel research. Cloning of the genes encoding lignocellulose-digesting enzymes and evaluation of pure mussel enzyme capabilities would appear promising.