A commercial laccase-mediator system to delignify and improve saccharification of the fast-growing Paulownia fortunei (Seem.) Hemsl.
Summary (2 min read)
- Its properties such a lightweight, strength, insulation, fast drying, high ignition point and rot resistance makes it popular for house construction and furniture making.
- Paulownia also has a potential use as energy crop for the production of bioethanol (Ye et al. 2016; Domínguez et al. 2017) also by enzymatic hydrolysis (Chandra et al. 2007) and subsequent fermentation by yeasts (Park et al. 2013) or bacteria (Ng et al. 1981) to ethanol.
- Different physical and chemical pretreatments have been proposed for a better saccharification of paulownia wood, such as dilute acid, alkali, ultrasonic-assisted alkali treatments (Ye et al. 2015, 2016), autohydrolysis (Domínguez et al. 2017), and steam explosion (Radeva et al. 2012).
- Methyl syringate (MeS) will serve as mediator, which is obtained from syringic acid present in pulp and paper side-streams (Rosado et al. 2012).
Material and methods
- Paulownia wood, enzymes and mediator: 3-year-old P. fortunei trees were provided by the University of Huelva .
- At the 95% confidence level, the enzymatic experiments are smaller than the differences found between the control, laccase alone, and L/MeS treatments.
- The 2D HSQC NMR experiments were performed at the gel state, which is an in situ analysis of the whole cell-wall (Kim et al. 2008, Rencoret et al. 2009b).
- The 1H-13C correlation signals from the aromatic region of the spectrum were used to estimate the content of lignin (relative to the content of amorphous carbohydrates, estimated from the anomeric xylose and glucose signals), and the lignin composition in terms of G, S and oxidized S (S′) and G (G′) units.
- The extraction process was repeated three times, using fresh chloroform each time and the supernatants were combined.
Result and discussion
- Delignification of paulownia wood by the enzymatic pretreatment The Klason lignin content of the paulownia control, processed as the full enzymatic treatment but without laccase and mediator, was only slightly reduced from 23.8 to 22.0% with respect to the initial paulownia lignin content (Table 1).
- This is the effect of alkaline peroxide extractions.
- The treatment with laccase alone only resulted in a 5% lignin reduction compared to the control sample.
- This low efficiency of laccase alone is well known (Lai, 1992).
- The pretreatment with L/MeS, however, resulted in a lignin decrement up to 24%, with respect to the control, but this delignification is degree is lower than reported about eucalypt wood Page 7 of 23 https://mc.manuscriptcentral.com/holz.
- The lignin in paulownia wood was modified and partially removed by pretreatment with recombinant laccase of M. thermophila in the presence of MeS as phenolic mediator, in spite of its high G-unit content.
- The L/MeS system acts selectively on the lignin polymer, leaving the carbohydrate signals in the HSQC spectra practically unaffected.
- The utilization of The commercially available L/MeS system has a high application potential as pretreatment for the saccharification of paulownia wood.
- The authors thank Dr. Manuel Angulo (CITIUS, University of Seville) for technical assistance with the NMR experiments.
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Cites methods from "A commercial laccase-mediator syste..."
...This technique is commonly used to understand lignin chemistry (23, 24), including to elucidate modifications by chemical catalysts (25) and ligninolytic enzymes (26, 27)....
"A commercial laccase-mediator syste..." refers methods in this paper
...Seventy milligrams of ball-milled samples (and filtrate samples) were transferred into 5-mm NMR tubes and swelled in 1 ml of DMSO-d6, forming a gel inside the tube (Kim et al. 2008; Rencoret et al. 2009b)....
...2D-NMR analyses: The 2D heteronuclear single quantum coherence (HSQC) NMR experiments were performed at the gel state, which is an in situ analysis of the whole cell wall (Kim et al. 2008; Rencoret et al. 2009b)....
...The modification of the structure of the lignin polymer in the pretreated paulownia was monitored by two dimensional-nuclear magnetic resonance (2D-NMR) spectroscopy of the whole sample at the gel state (Kim et al. 2008; Rencoret et al. 2009b), and the effect of the L/MeS treatment on the saccharification yield was reported....
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Q1. What contributions have the authors mentioned in the paper "Short title: enzymatic pretreatment of p. fortunei a commercial laccase-mediator system to delignify and improve saccharification of the fast-growing paulownia fortunei" ?
Up to 24 % lignin removal was attained by the laccase-mediator treatment ( L/MeS ), followed by alkaline peroxide extraction in a multistage sequence.