Identification and Characterization of a Novel Plasmid-Encoded Laccase-Like Multicopper Oxidase from Ochrobactrum sp. BF15 Isolated from an On-Farm Bio-Purification System

MARTINI, C; BERINI, F; AUSEC, L; CASCIELLO, C; VACCA, CAROLINA; PISTORIO, M.; LAGARES, A.; MANDIC-MULEC, I; MARINELLI, F; DEL PAPA, M.F.

FOOD TECHNOLOGY AND BIOTECHNOLOGY

FACULTY FOOD TECHNOLOGY BIOTECHNOLOGY

Lugar: Zagreb; Año: 2021 vol. 59 p. 519 - 529

1330-9862

Research background. In recent decades, laccases (p-diphenol-dioxygen oxidoreduc¬tases; EC 1.10.3.2) have attracted the attention of researchers due to their wide range of biotechnological and industrial applications. Laccases can oxidize a variety of organic and inorganic compounds, making them suitable as biocatalysts in biotechnological process¬es. Even though the most traditionally used laccases in the industry are of fungal origin, bacterial laccases have shown an enormous potential given their ability to act on several substrates and in multiple conditions. The present study aims to characterize a plasmid-en¬coded laccase-like multicopper oxidase (LMCO) from Ochrobactrum sp. BF15, a bacterial strain previously isolated from polluted soil. Experimental approach. We used in silico profile hidden Markov models to identify nov¬el laccase-like genes in Ochrobactrum sp. BF15. For laccase characterization, we performed heterologous expression in Escherichia coli, purification and activity measurement on typ¬ical laccase substrates. Results and conclusions. Profile hidden Markov models allowed us to identify a novel LMCO, named Lac80. In silico analysis of Lac80 revealed the presence of three conserved copper oxidase domains characteristic of three-domain laccases. We successfully ex¬pressed Lac80 heterologously in E. coli, allowing us to purify the protein for further activ¬ity evaluation. Of thirteen typical laccase substrates tested, Lac80 showed lower activity on 2,2?-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), pyrocatechol, py¬rogallol and vanillic acid, and higher activity on 2,6-dimethoxyphenol. Novelty and scientific contribution. Our results show Lac80 as a promising laccase for use in industrial applications. The present work shows the relevance of bacterial laccases and highlights the importance of environmental plasmids as valuable sources of new genes encoding enzymes with potential use in biotechnological processes