Effect of adding surfactant for transforming lignocellulose into fermentable sugars during biocatalysing

Zhang, Yuqing; Xu, Xuemin; Zhang, Yuyuan; Li, Jianfa

doi:10.1007/s12257-011-0138-z

Cited by 35 publications

(21 citation statements)

References 22 publications

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“…Several previous studies reported that many different types of additives enhanced the degradation of cellulose. For example, cellulase-catalyzed degradation of cellulose was enhanced by the addition of PEG 4000 [ 8 , 20 ], Tween 20 [ 10 , 21 ] or BSA [ 11 , 22 ]. Therefore, we next confirmed that these three additives indeed enhanced cellulose degradation.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, several cationic surfactants, but not anionic surfactants, enhanced the hydrolysis process [ 5 ]. There were also several other studies demonstrating the ability of surfactants in enhancing the rate of hydrolysis [ 6 – 8 ]. One study showed that the non-ionic surfactants were more effective at low cellulase concentration [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

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Enhancement of Cellulose Degradation by Cattle Saliva

et al. 2015

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Saccharification of cellulose is a promising technique for producing alternative source of energy. However, the efficiency of conversion of cellulose into soluble sugar using any currently available methodology is too low for industrial application. Many additives, such as surfactants, have been shown to enhance the efficiency of cellulose-to-sugar conversion. In this study, we have examined first whether cattle saliva, as an additive, would enhance the cellulase-catalyzed hydrolysis of cellulose, and subsequently elucidated the mechanism by which cattle saliva enhanced this conversion. Although cattle saliva, by itself, did not degrade cellulose, it enhanced the cellulase-catalyzed degradation of cellulose. Thus, the amount of reducing sugar produced increased approximately 2.9-fold by the addition of cattle saliva. We also found that non-enzymatic proteins, which were present in cattle saliva, were responsible for causing the enhancement effect. Third, the mechanism of cattle saliva mediated enhancement of cellulase activity was probably similar to that of the canonical surfactants. Cattle saliva is available in large amounts easily and cheaply, and it can be used without further purification. Thus, cattle saliva could be a promising additive for efficient saccharification of cellulose on an industrial scale.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhancement of Cellulose Degradation by Cattle Saliva

et al. 2015

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“…Qin et al [ 138 ] used atomic force microscopy (AFM) to measure the adhesion forces between lignin and enzyme and found that hydrogen bonding promoted the lignin–enzyme interaction to some extent. Zhang et al [ 150 ] found that the addition of the surfactant such as PEG could form the hydrogen bonding with the phenolic hydroxyls of lignin, which prevented the non-productive adsorption of cellulase onto lignin through hydrogen bonding. In addition, aliphatic hydroxyl groups in lignin have been reported to be involved in hydrogen bond formation as well.…”

Section: Interaction Between Lignin and Cellulasementioning

confidence: 99%

Recent advances in understanding the effects of lignin structural characteristics on enzymatic hydrolysis

Yuan

Jiang

Chen

et al. 2021

Biotechnol Biofuels

143

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Enzymatic hydrolysis of lignocellulose for bioethanol production shows a great potential to remit the rapid consumption of fossil fuels, given the fact that lignocellulose feedstocks are abundant, cost-efficient, and renewable. Lignin results in low enzymatic saccharification by forming the steric hindrance, non-productive adsorption of cellulase onto lignin, and deactivating the cellulase. In general, the non-productive binding of cellulase on lignin is widely known as the major cause for inhibiting the enzymatic hydrolysis. Pretreatment is an effective way to remove lignin and improve the enzymatic digestibility of lignocellulose. Along with removing lignin, the pretreatment can modify the lignin structure, which significantly affects the non-productive adsorption of cellulase onto lignin. To relieve the inhibitory effect of lignin on enzymatic hydrolysis, enormous efforts have been made to elucidate the correlation of lignin structure with lignin–enzyme interactions but with different views. In addition, contrary to the traditional belief that lignin inhibits enzymatic hydrolysis, in recent years, the addition of water-soluble lignin such as lignosulfonate or low molecular-weight lignin exerts a positive effect on enzymatic hydrolysis, which gives a new insight into the lignin–enzyme interactions. For throwing light on their structure–interaction relationship during enzymatic hydrolysis, the effect of residual lignin in substrate and introduced lignin in hydrolysate on enzymatic hydrolysis are critically reviewed, aiming at realizing the targeted regulation of lignin structure for improving the saccharification of lignocellulose. The review is also focused on exploring the lignin–enzyme interactions to mitigate the negative impact of lignin and reducing the cost of enzymatic hydrolysis of lignocellulose.

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“…Therefore, simultaneous saccharification and co-fermentation process was suggested for cellulosic ethanol production in which the cellulase and yeast co-exist and complement in the overall process 40 . While some PEGs have been used in the enzymatic hydrolysis of cellulose from lignocellulosic mass to improve the enzymatic efficiency 41 , we further demonstrated the potential of PEG chemically exo-protected industrial starch-base S. Cerevisiae for ethanol production throuth a simultaneous saccharification and co-fermentation process from a representative real world lignocellulose feedstock. For a polar pretreated by low-cost steam hydrolysis combined with explosion, PEG-1000 enhanced ethanol productivity by 3 fold as compared to that in the absence of PEGs in the fermentation broth.…”

Section: Discussionmentioning

confidence: 88%

Lignocellulosic ethanol production by starch-base industrial yeast under PEG detoxification

Liu

Mao

et al. 2016

Sci Rep

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Cellulosic ethanol production from lignocellulosic biomass offers a sustainable solution for transition from fossil based fuels to renewable alternatives. However, a few long-standing technical challenges remain to be addressed in the development of an economically viable fermentation process from lignocellulose. Such challenges include the needs to improve yeast tolerance to toxic inhibitory compounds and to achieve high fermentation efficiency with minimum detoxification steps after a simple biomass pretreatment. Here we report an in-situ detoxification strategy by PEG exo-protection of an industrial dry yeast (starch-base). The exo-protected yeast cells displayed remarkably boosted vitality with high tolerance to toxic inhibitory compounds, and with largely improved ethanol productivity from crude hydrolysate derived from a pretreated lignocellulose. The PEG chemical exoprotection makes the industrial S. cerevisiae yeast directly applicable for the production of cellulosic ethanol with substantially improved productivity and yield, without of the need to use genetically modified microorganisms.Cellulosic ethanol from lignocellulosic biomass through biological fermentation has been recognized as a sustainable transportation fuel due to the most abundant carbohydrate content of the broadly distributed non-food feedstock 1-3 . Very high gravity (VHG) fermentation, referring to the fermentation of high sugar concentrations, offers the advantages of improved overall ethanol productivity (producing ethanol in 10-15 vol%), reduced capital cost, and reduced energy input compared to processes at normal gravity 4 . This technology represents a major progress toward cost-competitive production of cellulosic ethanol. With lignocellulosic biomass as the feedstock, a pretreatment process is typically necessary to generate monomeric sugars from the polysaccharide components of the biomass for the subsequent fermentation process. However, typical pretreatment processes of lignocellulosic materials inevitably generate degradation compounds, e. g., acetic and formic acids, furfural, and 5-hydroxymethylfurfural (HMF) and phenolic compounds [5][6][7] . The residue of these compounds often exists in fermentation broth and functions as toxic inhibitors [8][9][10] . To achieve fermentable sugars in a high-concentration for VHG fermentation, the biomass loading ratio during pretreatment must be increased to a considerably high level, which typically results in high concentrations of inhibitors in the fermentation broth. These inhibitors often significantly reduce the rates of yeast metabolism and the final ethanol titers in the subsequent fermentation step 11,12 . The detrimental effect of the inhibitors remains one of the major barriers to the development of an economically viable process for cellulosic ethanol production [13][14][15] . To overcome the issues related to the inhibitory compounds in the lignocellulosic hydrolysates, some techniques on detoxifying the hydrolysates by removing the toxic chemical residues have been repo...

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Effect of adding surfactant for transforming lignocellulose into fermentable sugars during biocatalysing

Cited by 35 publications

References 22 publications

Enhancement of Cellulose Degradation by Cattle Saliva

Enhancement of Cellulose Degradation by Cattle Saliva

Recent advances in understanding the effects of lignin structural characteristics on enzymatic hydrolysis

Lignocellulosic ethanol production by starch-base industrial yeast under PEG detoxification

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