Laccases ethanol

Lignophenols having a linear structure were obtained by the surface reaction of a native lignin and phenols in sulfuric acid. Laccase catalyzed the oxidative polymerization of lignocatechol in a mixture of ethanol and phosphate buffer to give the crosslinked polymer [92]. The product showed high affinity for bovine serum albumin and glucoamylase. 

Bark of P. taeda obtained from a pulp mill in Mississippi was milled, extracted, activated, and reacted with bisaminopropylethylenediamine (BAPED). The modification was made to increase the capacity of the bark to adsorb anions. Modified bark (0.5 to 0.7 g) in 5 mL of 40 mM tartarate buffer pH 5.0 and 10 pL laccase was mixed for 30 min at room temperature. Phloroglucinol (1 mL of 0.3 M in ethanol) or catechol (1 mL of 0.3 M) were added and incubated for 3 h at room temperature, followed by 18 h at 5°C. The particles were rinsed and recovered by filtration and freeze dried. Controls included laccase addition without substrate and untreated modified bark. The bark was tested for the ability to remove phosphate from solution. 

Alternative methods have been sought to both shorten and provide more objective evaluation of rot. Such methods have included identification and quantification of key indicator metabolites of mold (laccase and/or glycerol), bacterial (acetic acid), and native yeast (ethanol) activity. 

The physical processes of racking and clarification (with bentonite) help remove the enzyme fraction associated with particulate materials (Gortegs and Geisenheim, 1986). In addition, the activity of tyrosinase decreases during yeast fermentation, largely because of the production of ethanol. Consequently, clarified protein-stable wines made from relatively sound berries are unlikely to contain significant quantities of either laccase or tyrosinase and, hence, should undergo little enzymatic oxidation (Simpson, 1980). 

Treatment with the enzymes peroxidase and laccase, obtained from the ligninolytic fungus Trametes versicolor, has been shown to increase the maximum ethanol productivity in a hemicellulose hydrolysate (Palmqvist and Hahn-Hagerdal, 2000). To detoxify phenolic inhibitors, laccase from T. versicolor was expressed in S. cerevisiae. The laccase expressing strain had the ability to convert coniferyl aldehyde at a faster rate than a control strain not expressing laccase, which enabled faster growth and ethanol fermentation in the presence of coniferyl aldehyde (Larsson et al., 2001). 

First generation ethanol Hemicelluloses High ethanol titers Laccase... 

In 2011, alcohol dehydrogenase (ADH) was used as a model enzyme coupled with poly (MG) for NADH reoxidation in the construction of a three-dimensional BFC with ethanol as fuel [103]. In combination with an air-breathing/gas difhision cathode (using laccase as an oxygen reduction enzyme), a BFC was fabricated that was able to successfully exploit ethanol oxidation by an NAD -dependent ADH, immobilized by entrapment in a multiwaUed CNT (MWCNT)/chitosan matrix [106]. The feasibility and reproducibUity of the resulting BFC were demonstrated in 2008 with a series of standardized multilaboratory experiments [96]. 

FIGURE 4.7 Polarization curves of (A) ADH anode, ( ) laccase cathode, and ( ) the fully assembled biological fuel cell. Dashed line represents the theoretical full cell polarization curve. Ethanol concentration 475 mM open-circuit voltage=0.618 V. (Reprinted with permission from Ref. [103]. Copyright 2011, Elsevier.)... 

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