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- Title
A thermostable laccase from Thermus sp. 2.9 and its potential for delignification of Eucalyptus biomass.
- Authors
Navas, Laura E.; Martínez, Fernando D.; Taverna, María E.; Fetherolf, Morgan M.; Eltis, Lindsay D.; Nicolau, Verónica; Estenoz, Diana; Campos, Eleonora; Benintende, Graciela B.; Berretta, Marcelo F.
- Abstract
Laccases are multicopper oxidases that are being studied for their potential application in pretreatment strategies of lignocellulosic feedstocks for bioethanol production. Here, we report the expression and characterization of a predicted laccase (LAC_2.9) from the thermophilic bacterial strain Thermus sp. 2.9 and investigate its capacity to delignify lignocellulosic biomass. The purified enzyme displayed a blue color typical of laccases, showed strict copper dependence and retained 80% of its activity after 16 h at 70 °C. At 60 °C, the enzyme oxidized 2,2′-azino-di-(3-ethylbenzthiazoline sulfonate) (ABTS) and 2,6-dimethoxyphenol (DMP) at optimal pH of 5 and 6, respectively. LAC_2.9 had higher substrate specificity (kcat/KM) for DMP with a calculated value that accounts for one of the highest reported for laccases. Further, the enzyme oxidized a phenolic lignin model dimer. The incubation of steam-exploded eucalyptus biomass with LAC_2.9 and 1-hydroxybenzotriazole (HBT) as mediator changed the structural properties of the lignocellulose as evidenced by Fourier transform infrared (FTIR) spectroscopy and thermo-gravimetric analysis (TGA). However, this did not increase the yield of sugars released by enzymatic saccharification. In conclusion, LAC_2.9 is a thermostable laccase with potential application in the delignification of lignocellulosic biomass.
- Subjects
EUCALYPTUS; LACCASE; BIOMASS; BIOMASS energy; THERMUS thermophilus
- Publication
AMB Express, 2019, Vol 9, Issue 1, p1
- ISSN
2191-0855
- Publication type
Article
- DOI
10.1186/s13568-019-0748-y