Abstract:Genome search of Geobacillus thermopakistaniensis, formerly Geobacillus sp. SBS-4S, revealed the presence of an open reading frame (ESU71923) annotated as laccase. However, the gene product did not display any laccase-like activity against the substrates examined. The laccase activity was, therefore, purified from G. thermopakistaniensis cells and N-terminal amino acid residues of the enzyme were determined. These residues matched the N-terminal sequence of an open reading frame annotated as a copper oxidase (… Show more
“…The dependence of the activity on Cu 2+ concentration was sigmoidal. Similar behavior has been documented in other bacterial laccases (Basheer et al 2017; Kim et al 2015; Miyazaki 2005), with some authors suggesting the existence of an extra copper binding site that is essential for activity. Subsequent kinetic characterization was performed using assay buffers containing 1 mM CuSO 4 .Fig.…”
Section: Resultssupporting
confidence: 82%
“…However, bacterial laccases possess a variety of attractive characteristics as compared to fungal laccases, especially with respect to pH-range of activity, thermal stability and resistance to chlorides (Chauhan et al 2017). In addition, laccases from extremophiles have garnered attention for industrial processes that require harsh conditions, with a few reports of laccases isolated from thermophilic bacteria (Al-kahem Al-balawi et al 2017; Basheer et al 2017; Fernandes et al 2007). Indeed, enzymes from different strains of Thermus thermophilus have been found to be useful for the bleaching of wheat straw pulp (Zheng et al 2012) and the decolorization of dyes (Kumari et al 2018; Liu et al 2015).…”
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 (
k
cat
/
K
M
) 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.
Electronic supplementary material
The online version of this article (10.1186/s13568-019-0748-y) contains supplementary material, which is available to authorized users.
“…The dependence of the activity on Cu 2+ concentration was sigmoidal. Similar behavior has been documented in other bacterial laccases (Basheer et al 2017; Kim et al 2015; Miyazaki 2005), with some authors suggesting the existence of an extra copper binding site that is essential for activity. Subsequent kinetic characterization was performed using assay buffers containing 1 mM CuSO 4 .Fig.…”
Section: Resultssupporting
confidence: 82%
“…However, bacterial laccases possess a variety of attractive characteristics as compared to fungal laccases, especially with respect to pH-range of activity, thermal stability and resistance to chlorides (Chauhan et al 2017). In addition, laccases from extremophiles have garnered attention for industrial processes that require harsh conditions, with a few reports of laccases isolated from thermophilic bacteria (Al-kahem Al-balawi et al 2017; Basheer et al 2017; Fernandes et al 2007). Indeed, enzymes from different strains of Thermus thermophilus have been found to be useful for the bleaching of wheat straw pulp (Zheng et al 2012) and the decolorization of dyes (Kumari et al 2018; Liu et al 2015).…”
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 (
k
cat
/
K
M
) 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.
Electronic supplementary material
The online version of this article (10.1186/s13568-019-0748-y) contains supplementary material, which is available to authorized users.
“…This semi-quantitative assay is usually employed with a limited range of electron-donor substrates, pH and temperature conditions. 31,36,38,39,44,46,139,165,167,189,[191][192][193][194][195][196][197][198][199][200][201][202] Examples of how this data is presented are shown in Fig. 3.…”
Section: Semi-quantitative Assaysmentioning
confidence: 99%
“…Some researchers studying inhibition in terms of relative activity have described an activation phenomenon whereby an inhibitor enhances MCO activity, 34,45,46,165,[192][193][194]198,199 exemplified with KBr in Fig. 3B and NaCl in Fig.…”
Multicopper oxidases (MCO), such as laccases and bilirubin oxidases, are catalysts of wide interest to a range of biotechnological applications, especially bioremediation and energy transduction. Many of these processes take...
“…Infiltration in life can be seen everywhere, for example, the excess energy consumed by a ship sailing due to hydraulic friction [1]. Interest in super-hydrophobic surfaces has increased in recent years [2][3][4][5][6]. Hydrophobicity and stain resistance are widely used in many areas such as anti-biofouling surfaces in a marine environment [7][8][9][10], fluid drag reduction [11,12], anti-contamination surfaces of windows for buildings and automobiles [13][14][15], microfluid [16,17], and many others.…”
The hydrophobicity and anti-fouling properties of materials have important application value in industrial and agricultural production and people's daily life. To study the relationship between the unit width L 0 of the parabolic hydrophobic material and the hydrophobicity and anti-fouling properties, the rough surface structure of the parabolic with different widths was prepared by grinding with different SiC sandpapers, and further, to obtain hydrophobic materials through chemical oxidation and chemical etching, and modification with stearic acid (SA). The morphology, surface wetting and anti-fouling properties of the modified materials were characterized by SEM and contact angle measurement. The oil-water separation performance and self-cleaning performance of the materials were explored. The surface of the modified copper sheet forms a rough structure similar to a paraboloid. When ground with 1500 grit SiC sandpaper, it is more conducive to increase the hydrophobicity of the copper sheet surface and increase the contact angle of water droplets on the copper surface. Additionally, the self-cleaning and anti-fouling experiments showed that as L 0 decreases, copper sheets were less able to stick to foreign things such as soil, and the better the self-cleaning and anti-fouling performance was. Based on the oil-water separation experiment of copper mesh, the lower L 0 has a higher oil-water separation efficiency. The results showed that material with parabolic morphology has great self-cleaning, anti-fouling, and oil-water separation performance. The smaller the L 0 was, the larger the contact angle and the better hydrophobic performance and self-cleaning performance were.
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