Article

Impact of surfactants on pretreatment of corn stover.

Center for Environmental Research and Technology, Chemical and Environmental Engineering Department, Bourns College of Engineering, University of California, 1084 Columbia Avenue, Riverside, CA 92507, USA.
Bioresource Technology (Impact Factor: 5.04). 03/2010; 101(15):5941-51. DOI: 10.1016/j.biortech.2010.03.003
Source: PubMed

ABSTRACT Lignin in pretreated cellulosic biomass can non-productively adsorb cellulase, resulting in loss of a significant portion of this expensive protein. In addition, lignin interferes with the path for cellulase action, slowing down hydrolysis. Thus, the effectiveness of enzymatic hydrolysis of pretreated lignocellulosic biomass can be significantly enhanced if lignin is removed or effectively modified before adding enzymes. In this study, the enzymatic digestibilities of solids resulting from using the surfactants Tween-80, dodecylbenzene sulfonic acid, and polyethylene glycol 4000 during water-only or dilute acid pretreatment of corn stover at 140-220 degrees C were evaluated. All of these surfactants increased lignin removal during pretreatment and reduced non-productive binding of enzymes on the biomass surface, but Tween-80 increased enzymatic hydrolysis yields and enhanced total sugar recovery more than the other two. Surfactant pretreatment was found to improve lignin solubility, which could improve cellulose digestibility by reducing unproductive binding to enzyme, and also appeared to enhance performance by modifying the biomass surface.

2 Bookmarks
 · 
237 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Liquid hot water (LHW) pretreatment is an effective and environmentally friendly method to produce bioethanol with lignocellulosic materials. In our previous study, high ethanol concentration and ethanol yield were obtained from water-insoluble solids (WIS) of reed straw and corn stover pretreated with LHW by using fed-batch semi-simultaneous saccharification and fermentation (S-SSF). However, high cellulase loading and the large amount of wash water possibly limit the practical application of LHW pretreatment. To decrease cellulase loading and the amount of wash water, we performed Tween 40 pretreatment before WIS was subjected to bioethanol fermentation. Results showed that the optimum conditions of Tween 40 pretreatment were as follows: Tween 40 concentration of 1.5%, WIS-to-Tween 40 ratio of 1:10 (w/v), and pretreatment time of 1 hour at ambient temperature. After Tween 40 pretreatment, cellulase loading could be greatly reduced. After Tween 40 pretreatment, the residual liquid could be recycled for utilization but slightly affected ethanol concentration and yield. The unwashed WIS could obtain a high ethanol concentration of 56.28 g/L (reed straw) and 52.26 g/L (corn stover) by Tween 40 pretreatment using fed-batch S-SSF. Ethanol yield reached a maximum of 69.1% (reed straw) and 71.1% (corn stover). Tween 40 pretreatment was a very effective and less costly method with unwashed WIS. This pretreatment could greatly reduce cellulase loading and save wash water. Higher ethanol concentration was obtained almost without reducing ethanol yield.
    Biotechnology for Biofuels 11/2013; 6(1):159. · 5.55 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The addition of non-ionic surfactants has recently been confirmed to positively affect the enzymatic hydrolysis of cellulosic materials. However, the functional mechanisms of these surfactants remain unclear. This work investigated the influence of poly(ethylene glycol) (PEG) on the enzymatic hydrolysis of three cellulosic materials, namely, acid steam-exploded corn straw, pure microcrystalline cellulose (Avicel PH101), and bagasse sulfite pulp (BSP). The results showed that PEG addition led to varied effects on the enzymatic hydrolysis of different cellulosic materials. Addition of PEG was most effective on the enzymatic hydrolysis of PH101 and weakly effective on the hydrolysis of BSP. We further investigated PEG concentrations and enzymatic activities in the supernatant during hydrolysis and found that the positive effects of PEG treatment might contribute to its influence on enzyme desorption from different substrates. We also found that the efficiency of PEG depended on its capacity to bind to different substrates. PEG exhibited stronger affinity to pure cellulose than to the two other lignocellulosic substrates. These findings are helpful in further revealing the mechanism of surfactants and improving the enzymatic hydrolysis process.
    BioEnergy Research 12/2013; · 4.25 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Addition of additives has been confirmed to increase cellulase performance in the hydrolysis of lignocellulosic materials. In the hydrolysis of xylan-containing lignocellulosic biomass, xylanase can synergistically enhance the performance of cellulase. However, the role of additives in xylan hydrolysis by xylanase is not yet clear. In this work, with the presence of additives (bovine serum albumin, poly(ethylene glycol), and Tween), the hydrolysis of isolated xylan and the xylan in corn stover increased to different extents. Additives increased free xylanase in supernatants in the hydrolysis with xylanase, indicating the reduction of the adsorption of xylanase on corn stover and insoluble xylan. Enhanced hydrolysis of Avicel and corn stover by additives suggested that besides the prevention of unproductive binding of xylanase to lignin by additives, reducing the adsorption of xylanase on substrates was also contributed to enzymatic hydrolysis. The increment of xylanase activity by additives suggests that the additives were activators of xylanase. The results of this work indicate that the supplementation of additives could improve xylanase performance, synergistically enhanced the cellulose hydrolysis, and beneficial for the recycling of xylanase.
    Applied biochemistry and biotechnology 12/2013; · 1.94 Impact Factor

Full-text (2 Sources)

View
199 Downloads
Available from
Jun 4, 2014