Enzymatic saccharification of hydrogen peroxide-treated solids from hydrothermal processing of rice husks

Yáñez, Remedios; Alonso, José Luís; Parajó, Juan Carlos

doi:10.1016/j.procbio.2005.12.020

Cited by 34 publications

(8 citation statements)

References 17 publications

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“…2. The levels of cellulosic glucose and hemicellulosic xylose are similar to those reported previously for rice straw [3, 24, 25] and hulls [3, 13]. The steam explosion pretreatment and washing reduced the levels of insoluble hemicellulosic xylose as severity increased.…”

Section: Resultssupporting

confidence: 85%

“…A range of pretreatments have been assessed, including steam explosion [7, 8], steam explosion and biological pretreatment [9], alkaline pulping [10], microwave alkali heating [3] organosolvent pretreatments [11] and fine milling [12]. There have been comparatively fewer studies on rice husk which have included investigations into microwave alkali heating [3], hydrogen peroxide treatments [13] and wet air oxidation [14]. Very few studies have used one of the most promising pretreatment technologies, steam explosion, for rice husks in relation to enzymatic saccharification with or without fermentation [15].…”

Section: Introductionmentioning

confidence: 99%

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Comparison of saccharification and fermentation of steam exploded rice straw and rice husk

Wood

Cao

Tran

et al. 2016

Biotechnol Biofuels

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BackgroundRice cultivation produces two waste streams, straw and husk, which could be exploited more effectively. Chemical pretreatment studies using rice residues have largely focussed on straw exploitation alone, and often at low substrate concentrations. Moreover, it is currently not known how rice husk, the more recalcitrant residue, responds to steam explosion without the addition of chemicals.ResultsThe aim of this study has been to systematically compare the effects of steam explosion severity on the enzymatic saccharification and simultaneous saccharification and fermentation of rice straw and husk produced from a variety widely grown in Vietnam (Oryza sativa, cv. KhangDan18). Rice straw and husk were steam exploded (180–230 °C for 10 min) into hot water and washed to remove fermentation inhibitors. In both cases, pretreatment at 210 °C and above removed most of the noncellulosic sugars. Prolonged saccharification at high cellulase doses showed that rice straw could be saccharified most effectively after steam explosion at 210 °C for 10 min. In contrast, rice husk required more severe pretreatment conditions (220 °C for 10 min), and achieved a much lower yield (75 %), even at optimal conditions. Rice husk also required a higher cellulase dose for optimal saccharification (10 instead of 6 FPU/g DM). Hemicellulase addition failed to improve saccharification. Small pilot scale saccharification at 20 % (w/v) substrate loading in a 10 L high torque bioreactor resulted in similarly high glucose yields for straw (reaching 9 % w/v), but much less for husk. Simultaneous saccharification and fermentation under optimal pretreatment and saccharification conditions showed similar trends, but the ethanol yield from the rice husk was less than 40 % of the theoretical yield.ConclusionsDespite having similar carbohydrate compositions, pretreated rice husk is much less amenable to saccharification than pretreated rice straw. This is likely to attenuate its use as a biorefinery feedstock unless improvements can be made either in the feedstock through breeding and/or modern biotechnology, or in the pretreatment through the employment of improved or alternative technologies. Physiological differences in the overall chemistry or structure may provide clues to the nature of lignocellulosic recalcitrance.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0599-6) contains supplementary material, which is available to authorized users.

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Section: Resultssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Comparison of saccharification and fermentation of steam exploded rice straw and rice husk

Wood

Cao

Tran

et al. 2016

Biotechnol Biofuels

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“…The enzyme loading increase also favored the enzymatic hydrolysis of cellulose from hardwood (Gan et al 2003), softwood (Pan et al 2005), willow (Eklund et al 1990), sugarcane bagasse (Manonmani and Sreekantiah 1987), rice husks (Yáñez et al 2006), rice straw (Kaur et al 1998;Vlasenko et al 1997), and dairy manure fibers (Liao et al 2005). Nevertheless, the enzyme dosage required to achieve a complete conversion of cellulose into glucose vary to each raw material.…”

Section: Comparison Of Cellulose Conversion From Bsg With Other Lignomentioning

confidence: 99%

The effect of agitation speed, enzyme loading and substrate concentration on enzymatic hydrolysis of cellulose from brewer’s spent grain

et al. 2008

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Brewer's spent grain components (cellulose, hemicellulose and lignin) were fractionated in a two-step chemical pretreatment process using dilute sulfuric acid and sodium hydroxide solutions. The cellulose pulp produced was hydrolyzed with a cellulolytic complex, Celluclast 1.5 L, at 45°C to convert the cellulose into glucose. Several conditions were examined: agitation speed (100, 150 and 200 rpm), enzyme loading (5, 25 and 45 FPU/g substrate), and substrate concentration (2, 5 and 8% w/v), according to a 2 3 full factorial design aiming to maximize the glucose yield. The obtained results were interpreted by analysis of variance and response surface methodology. The optimal conditions for enzymatic hydrolysis of brewer's spent grain were identified as 100 rpm, 45 FPU/g and 2% w/v substrate. Under these conditions, a glucose yield of 93.1% and a cellulose conversion (into glucose and cellobiose) of 99.4% was achieved. The easiness of glucose release from BSG makes this substrate a raw material with great potential to be used in bioconversion processes.

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“…Factorial designs are a valuable tool for empirical modeling 28 and have been employed in literature for correlation and generalization of enzymatic hydrolysis data. [29][30][31] The structure of the experimental design allowed the calculation of the dependent variables (G MAX and t 1/2G , which are also named y 1 and y 2 for generalization purposes, respectively) as a function of the independent variables (LSR, ESR, and CCR, also denoted x 1 , x 2 , and x 3 , respectively, for generalization purposes). The interrelationship between dependent and independent variables was established by the equation where y j (j ) 1 or 2) represents the dependent variables, x i or x k (i or k ) 1-3, k g i) are the dimensionless, normalized, independent variables with variation ranges (-1, 1), and b 0j ...b ikj are regression coefficients, which can be calculated from experimental data.…”

Section: Enzymatic Hydrolysis Of Spent Solids From the Hydrothermal Tmentioning

confidence: 99%

Coproduction of Oligosaccharides and Glucose from Corncobs by Hydrothermal Processing and Enzymatic Hydrolysis

Garrote

Yáñez

Alonso

et al. 2008

Ind. Eng. Chem. Res.

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Corncobs were subjected to nonisothermal reaction in aqueous conditions to reach temperatures in the range 202-216°C. The liquors were assayed for composition to assess the conversion of xylan into oligosaccharides and reaction byproducts, whereas the spent solids from treatments were subjected to enzymatic hydrolysis. Enzymatic assays were carried out according to an incomplete, factorial, centered design of experiments, in which the following independent variables were considered: liquor to solid ratio (in the range 6-16 g/g), enzyme to substrate ratio (in the range 6-28 filter paper units/g), and -glucosidase activity/cellulase activity ratio (in the range 1-9 IU/FPU). The concentration/time data were fitted to an equation selected from the literature, and the model parameters were expressed as a function of the operational variables considered in the experimental design. Under selected conditions, high oligosaccharide yields and near quantitative cellulose conversion into glucose were obtained.

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Enzymatic saccharification of hydrogen peroxide-treated solids from hydrothermal processing of rice husks

Cited by 34 publications

References 17 publications

Comparison of saccharification and fermentation of steam exploded rice straw and rice husk

Comparison of saccharification and fermentation of steam exploded rice straw and rice husk

The effect of agitation speed, enzyme loading and substrate concentration on enzymatic hydrolysis of cellulose from brewer’s spent grain

Coproduction of Oligosaccharides and Glucose from Corncobs by Hydrothermal Processing and Enzymatic Hydrolysis

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