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Appl. Sci. 2013, 3(2), 396-419; doi:10.3390/app3020396
Review

A Review of the Role of Amphiphiles in Biomass to Ethanol Conversion

1,* , 1
 and 2
Received: 31 December 2012; in revised form: 18 February 2013 / Accepted: 25 February 2013 / Published: 2 April 2013
(This article belongs to the Special Issue Renewable Energy)
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Abstract: One of the concerns for economical production of ethanol from biomass is the large volume and high cost of the cellulolytic enzymes used to convert biomass into fermentable sugars. The presence of acetyl groups in hemicellulose and lignin in plant cell walls reduces accessibility of biomass to the enzymes and makes conversion a slow process. In addition to low enzyme accessibility, a rapid deactivation of cellulases during biomass hydrolysis can be another factor contributing to the low sugar recovery. As of now, the economical reduction in lignin content of the biomass is considered a bottleneck, and raises issues for several reasons. The presence of lignin in biomass reduces the swelling of cellulose fibrils and accessibility of enzyme to carbohydrate polymers. It also causes an irreversible adsorption of the cellulolytic enzymes that prevents effective enzyme activity and recycling. Amphiphiles, such as surfactants and proteins have been found to improve enzyme activity by several mechanisms of action that are not yet fully understood. Reduction in irreversible adsorption of enzyme to non-specific sites, reduction in viscosity of liquid and surface tension and consequently reduced contact of enzyme with air-liquid interface, and modifications in biomass chemical structure are some of the benefits derived from surface active molecules. Application of some of these amphiphiles could potentially reduce the capital and operating costs of bioethanol production by reducing fermentation time and the amount of enzyme used for saccharification of biomass. In this review article, the benefit of applying amphiphiles at various stages of ethanol production (i.e., pretreatment, hydrolysis and hydrolysis-fermentation) is reviewed and the proposed mechanisms of actions are described.
Keywords: lignocellulosic biomass; cellulase; enzymatic hydrolysis; pretreatment; surfactants lignocellulosic biomass; cellulase; enzymatic hydrolysis; pretreatment; surfactants
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Eckard, A.D.; Muthukumarappan, K.; Gibbons, W. A Review of the Role of Amphiphiles in Biomass to Ethanol Conversion. Appl. Sci. 2013, 3, 396-419.

AMA Style

Eckard AD, Muthukumarappan K, Gibbons W. A Review of the Role of Amphiphiles in Biomass to Ethanol Conversion. Applied Sciences. 2013; 3(2):396-419.

Chicago/Turabian Style

Eckard, Anahita D.; Muthukumarappan, Kasiviswanathan; Gibbons, William. 2013. "A Review of the Role of Amphiphiles in Biomass to Ethanol Conversion." Appl. Sci. 3, no. 2: 396-419.


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