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-Ethanol (square) and glycerol (circle) formation by P. stipitis grown on oat hull hemicellulosic hydrolysate treated (black symbol) or not (white symbol) with 1% activated charcoal.
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Oat hull hemicellulosic hydrolysate obtained by diluted acid hydrolysis was employed as fermentation medium for Pichia stipitis cultivation. A comparison between the use of treated hydrolysate with 1% activated charcoal to reduce the toxic compounds generated during the hydrolysis process and untreated hydrolysate as a control was conducted. In the...
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Context 1
... the use of untreated hydrolysate resulted in the morphological changes in yeast cells (data not showed), with consequently cell death after 48h of fermentation, which was not the case with the use of the treated hydrolysate, even with the partial removal of toxic compounds. Figure 3 shows the formation of ethanol and glycerol during the fermentation of oat hull hemicellulosic hydrolysate by P. stipitis. ...
Context 2
... high concentration of toxic compounds resulted in low sugar consumption by the yeast (Fig. 1A) and consequently also resulted in low ethanol production (Fig. 3). Ethanol formation was observed only by employing the medium formulated with the treated hydrolysate. In this condition, maximum ethanol formation (3.67g/L) was close to that reported by Klinner et al. (2005) in the study with P. stipitis in the synthetic medium containing only glucose (30g/L) as carbon source (ethanol around 5.0g/L) ...
Context 3
... containing glucose (30g/L) and xylose (30g/L) (ethanol 23g/L) and that observed by Nigam (2001) in wheat straw hemicellulosic hydrolysate with xylose (30g/l) and glucose (3g/L) (ethanol 15g/L). The low ethanol production employing the treated hydrolysate and no formation in untreated hydrolysate together with the formation of by- product glycerol (Fig. 3) were directly related to high concentrations of toxic compounds in the hydrolysate. The formation of glycerol, a compatible solute has been observed as a response to stressful conditions in yeast, imposed by the toxic compounds present in the hemicellulosic hydrolysates (Arruda and Felipe ...
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Currently, the fermentation technology for recycling agriculture waste for generation of alternative renewable biofuels is getting more and more attention because of the environmental merits of biofuels for decreasing the rapid rise of greenhouse gas effects compared to petrochemical, keeping in mind the increase of petrol cost and the exhaustion o...
Citations
... 11 The low bioethanol yield of 0.05 g/g-o.h. was due to testing the pre-hydrolyzate as a nutrient medium. 46 The use of acidic and enzymatic hydrolyzates from o.h. as nutrient broths for simultaneous coproduction of ethanol and xylite was reported. 12 The cellulose content of o.h. is comparable with that of wheat 47 and rice straw, 30 oat, and artichoke stalks. ...
Miscanthus, which can grow on marginal lands and capture CO2, has great potential as an industrial crop. A complete cycle to convert Miscanthus sacchariflorus, grown in Western Siberia (Russia), into bioethanol has successfully been implemented on a pilot scale and employed in downstream ethylene production for the first time. The Miscanthus bioprocessing technology involved mechanical comminution; HNO3-pretreatment; hydrolysis with commercial enzyme preparations CelloLux-A and BrewZyme BGX with cellulase–glucanase–xylanase action; pre-saccharification with substrate feed; simultaneous saccharification and fermentation with delayed inoculation (dSSF) with non-GMO Saccharomyces cerevisiae Y-1693 supplemented with or without (NH4)2SO4, KH2PO4 and yeast extract; rectification; and alumina-catalyzed dehydration to ethylene. Here we discussed pulp reactivity, yield and composition of Miscanthus products at each step (including ethylene), and compared the quality of the bioethanol obtained in the study with published data. The pulp feeding from 80 to 100 g/L resulted in a bioethanol concentration of ~40 g/L. It is the HNO3 pretreatment that provided pure bioethanol with an impurity content as low as 6.5 g/L. Bioethanol (92%-w) contained ~0.85 g/L impurities, mainly n-propanol and isobutanol; the latter weakly influenced the catalyst activity in ethylene production. The supplement slightly increased the yields of bioethanol and fusel alcohols, thereby reduced the yield of byproducts and improved the ethylene quality. The achieved yields of bioethanol and ethylene were 260 L/ton and 115 kg/ton Miscanthus, respectively. The expected yield of absolute ethylene under pilot-scale conditions can be 122 kg/ton Miscanthus.
... Food by-products (husks and straws) rich in lignocellulose are generated during the processing of these cereals in food industries. Among them, 11 million tons of oats are grown worldwide, and oat husk containing high sugar content (2.75-3.3 million tons) are produced by the processing of oats [3,4]. Lignocellulosic materials, including agricultural wastes and by-products, serve as a cheap and abundant feedstock. ...
In this study, ethanol organosolv treatment of oat husk and the potential effects of phosphoric acid and oxalic acid as alternatives to sulfuric acid were investigated. These acids were determined as effective as sulfuric acid to obtain high quality lignin and glucan and they can be used instead of sulfuric acid in solvent acidification. To determine the purity and recovery of both lignin and glucan, the effects of initial substrate amount, solid-to-liquid ratio, and amount of washing solutions were also examined using a one-factor-at-a-time strategy. Reducing the amount of washing solutions (water, solvent, or both) negatively affected lignin recovery, but it did not affect glucan recovery. The optimum conditions for pretreatment of the oat husk at higher glucan recovery were obtained with 50% aqueous ethanol acidified with oxalic acid at 210 °C for 90 min and solid-to-liquid ratio of 1:2. In the mixture of evaporated glucan-rich and hemicellulose-rich fractions obtained through the optimized condition, 4.62 g/L biomass containing 10.27% protein was produced by the cultivation of Aspergillus oryzae. The fractions obtained from organosolv treatment can be used to obtain value-added products such as biomass production, and thus contributing to a sustainable economy by integrating lignocellulosic sub-strate residues into the biorefinery.
... As shown in Fig. 4, both yeasts assimilated more than 52% of acetic acid present in the hydrolysate. Some authors also related the use of this acid by yeasts as an alternative carbon source to cell growth, mostly accomplished by raising medium pH [14,45]. However, the pH decrease was observed during the experiments, probably due to the formation of other acids by yeasts, but it was not evaluated. ...
In this study, a repeated-batch fermentation of hemicellulosic sugarcane bagasse hydrolysate was investigated to produce bioethanol using two xylose-fermenting yeasts, Scheffersomyces stipitis and Scheffersomyces shehatae. First, diluted-acid pretreatment of sugarcane bagasse at 150 mg H2SO4/g dry bagasse and 127 °C for 10 min, followed by concentration (3.5-fold), and detoxification process led to a hemicellulosic hydrolysate containing 48.97 g L⁻¹ xylose. The hemicellulosic hydrolysate was fermented using repeated-batch operation and studying the performance of S. stipitis and S. shehatae yeasts. The results showed that fermentative parameters through the repeated-batch were significantly increased, and the ability of yeasts was maintained during the two cycles (a total of third rounds). Furthermore, S. shehatae was 85% more efficient in xylose to ethanol conversion than S. stipitis, producing 21.5 g L⁻¹ ethanol that corresponds to YP/S = 0.436 g g⁻¹ and QP = 0.241 g L⁻¹ h⁻¹. In general, the use of sugarcane bagasse hemicellulosic fraction has been proved an excellent alternative to boost bioethanol production together the use of cellulose fraction, to replace fossil fuels. This work showed that the repeated-batch operation and S. shehatae yeast are possible combinations for industrial ethanol production from lignocellulosic hydrolysate.
... 11 The low bioethanol yield of 0.05 g/g-o.h. was due to testing the pre-hydrolyzate as a nutrient medium. 46 The use of acidic and enzymatic hydrolyzates from o.h. as nutrient broths for simultaneous coproduction of ethanol and xylite was reported. 12 The cellulose content of o.h. is comparable with that of wheat 47 and rice straw, 30 oat, and artichoke stalks. ...
... Oat husk is a lignocellulosic waste remaining after processing of oat which has a global production of 22 million metric tons (2018-2019), where EU is the highest producer (Chopda et al., 2020). Oat husk causes environmental pollution when it is disposed of in the traditional way which is combustion (Chaud et al., 2012;Cortivo et al., 2018). It is combusted to produce energy in some regions, and partially used as animal feed or high dietary food ingredient (Girardet and Webster, 2011). ...
... It is combusted to produce energy in some regions, and partially used as animal feed or high dietary food ingredient (Girardet and Webster, 2011). However, it has a potential to be used for production of valueadded products such as ethanol (Cortivo et al., 2018;Lawford et al., 2001), xylitol (Cortivo et al., 2018), animal feed etc. (Chaud et al., 2012). Chopda et al. (2020) studied acid-catalyzed organosolv pretreatment of oat husk in order to fractionate oat husk for further valorization. ...
This study was dedicated to techno-economic analysis of an integrated 1st and 2nd generation biorefinery, where the organosolv pretreated oat husk and thin stillage is valorized through filamentous fungi and baker yeast. By this strategy, process economy can benefit from multiple value-added products including lignin (80% purity), and protein-rich biomass as feed/food ingredients. Ethanol recovery of organosolv pretreatment benefits the already existing equipment in 1st generation ethanol plant. The best results shows that the integration of 10 tons/h oat husk into a process using 18.8 tons/h grains results in increasing ethanol production from 5.2 to 7.5 tons/h, in addition to 1.6 tons/h lignin (80% purity) and 7.6 tons/h fungal biomass. Integrated process is beneficial not only for 2nd but also for 1st generation ethanol production. Selling the fungal biomass as feed and food increased the net present value (NPV) in comparison to conventional ethanol plant by 71% and 7.9-fold, respectively.
... World production of oats accounts to approximately 11 million metric tons annually (FAOSTAT 2017). Thus, 2.75 million tons to 3.3 million tons of oat hulls are generated as grain-processing waste (Chaud et al. 2012). The proportion of hulls accounts for 25% to 30% of the dry grain weight (Chaud et al. 2012;Demirel et al. 2018). ...
... Thus, 2.75 million tons to 3.3 million tons of oat hulls are generated as grain-processing waste (Chaud et al. 2012). The proportion of hulls accounts for 25% to 30% of the dry grain weight (Chaud et al. 2012;Demirel et al. 2018). The high sugar content of hulls (as great as 70%) determines their potential use in biotechnological processes for the manufacture of high-value-added products such as ethanol (Germec et al. 2017;Demirel et al. 2018) and bacterial cellulose . ...
The pretreatment of lignocellulosic bioresources is a key step in obtaining fermentable sugars. The present study explored the recycling of an HNO3 cooking solution during one-step chemical pretreatment of oat hulls and examined the enzymatic hydrolysis performance of the resultant substrates. Two series of experiments on solution recycling were performed: stabilization and experimental elevation of HNO3 concentration by adding 70 wt% HNO3. When the HNO3 concentration was stabilized at 4.4 wt%, the solution could be used five times. Meanwhile, when the HNO3 concentration was experimentally elevated from 4.4 wt% to 5.6 wt% (at the tenth pretreatment) by adding 70 wt% HNO3, the cooking solution could be used ten times. The yield of reducing sugars on a hydrolyzables content basis was 95% to 99% for ten substrates. In this case, the lignin contents of the substrates did not increase and had no adverse effect on the enzymatic hydrolysis performance.
... A aveia quando processada libera em torno de 25 a 30% do seu peso em casca. A casca da aveia tem como função a proteção do grão contra fatores externos e tem sido descartada durante o processamento tornando-se um poluente ao meio ambiente (CHAUD et al., 2012). Sandrin (2013) ...
... A aveia quando processada libera em torno de 25 a 30% do seu peso em casca. A casca da aveia tem como função a proteção do grão contra fatores externos e tem sido descartada durante o processamento tornando-se um poluente ao meio ambiente (CHAUD et al., 2012). Sandrin (2013) determinou a composição centesimal da casca de aveia e verificou que os maiores constituintes químicos são celulose e hemicelulose, com menores quantidades de lignina. ...
... Polymers 2019, 11, 1645 2 of 17 an abundant and available raw source in agricultural regions worldwide, including Russia, and are basically regarded as pentose-rich biomass [26,27]. ...
Pretreatment of biomass is a key step in the production of valuable products, including high-tech bacterial cellulose. The efficiency of five different pretreatment methods of Miscanthus and oat hulls for enzymatic hydrolysis and subsequent synthesis of bacterial cellulose (BC) was evaluated herein: Hydrothermobaric treatment, single-stage treatments with dilute HNO3 or dilute NaOH solution, and two-stage combined treatment with dilute HNO3 and NaOH solutions in direct and reverse order. The performance of enzymatic hydrolysis of pretreatment products was found to increase by a factor of 4−7. All the resultant hydrolyzates were composed chiefly of glucose, as the xylose percentage in total reducing sugars (RS) was 1−9%. The test synthesis of BC demonstrated good quality of nutrient media prepared from all the enzymatic hydrolyzates, except the hydrothermobaric treatment hydrolyzate. For biosynthesis of BC, single-stage pretreatments with either dilute HNO3 or dilute NaOH are advised due their simplicity and the high performance of enzymatic hydrolysis of pretreatment products (RS yield 79.7−83.4%).
... From that moment, there was no increase in microbial biomass. When Chaud et al. (2012) used this same yeast grown in oat hull hemicellulosic hydrolysate (40 g/L xylose) a final biomass concentration close to 6 g/L was observed in 72 hours fermentation. ...
... Arabinose assimilation (data not shown) was not observed during the fermentation process. This behavior is consistent with the results reported in other works during fermentation with S. stipitis (Chaud et al., 2012;. Figure 4a shows that ethanol production increased from the 10 th hour of fermentation, reaching a maximum concentration of ethanol (22 g/L) at 55 hours. ...
This study aimed to determine the best dilute acid hydrolysis condition for the hemicellulosic fraction of sweet sorghum bagasse for ethanol production by Scheffersomyces stipitis. The experiment followed a 23 factorial design with four central points, and had as variables: sulfuric acid concentration, temperature and hydrolysis time. Sorghum bagasse presented the following chemical composition: 24.77% of lignin, 31.28% of hemicellulose and 34.80% of cellulose. The hydrolysis that resulted in the highest sugars concentration (14.22 g/L of xylose and 2.42 g/L glucose) was 1.75% H2SO4, 121 ºC and 40 minutes. This same condition provided low concentrations of toxic compounds (1.34 g/L of acetic acid, 0.90 g/L of phenol; 124.54 mg/L of hydroxymethylfurfural (HMF) and 978 mg/L of furfural). The fermentation of the hemicellulose-derived sugars by S. stiptis resulted in 22 g/L of ethanol, YP/S 0.40 g/g and Qp 0.34 g/L.h.
... Oat husk (OH) has occurred as an important by-product in the food industry due to the high sugars it contains, which is equivalent to 25-30% of dry weight of grain. Thus, 2.75-3.3 million tons of oat is generated as byproduct (Chaud et al. 2012). Therefore, BH and OH have great potential to be used in the production of value-added products by microbial fermentation after pretreatment process. ...
The pretreatment of renewable resources is the first step to make them metabolically available for microorganisms for generation of value-added products by fermentation. In this research, barley husk (BH) and oat husk (OH) were used as renewable resources to study the optimization of dilute acid pretreatment conditions by using Response Surface Methodology (RSM). Temperature (T, 110–130 °C), solid-to-liquid ratio (S:L, 1:8–1:16 w/v), dilute sulfuric acid concentration (DSA, 1–5%, v/v), and pretreatment time (t, 30–90 min) were selected as independent variables. Their levels were specified by one-factor-at-a-time (OFAT) method according to statistically significance level (p = 0.05). OFAT results indicated that the independent variables for optimization of acid pretreatment conditions of the renewable resources were T (120–130 °C), S:L (1:8–1:12 w/v), and DSA (1–3% v/v) for BH; T (120–130 °C), S:L (1:8–1:12 w/v), and t (10–30 min) for OH. Optimum pretreatment values were 130 °C, 1:8 (w/v), 1.86% (v/v), and 30 min for BH and 130 °C, 1:8 (w/v), 1% (v/v), and 19 min for OH by using Box-Behnken RSM. Under optimal conditions, fermentable sugar concentration, total phenolics, and extract yield were determined to be 76.28, 1.12 g/L, and 55% for BH and 59.63 g/L, 0.70 g/L, and 56% for OH, respectively. Additionally, the chemical composition of hydrolysates was also evaluated in terms of maltose, glucose, xylose, arabinose, mannose, galactose, phenolics, 5-hydroxymthylfurfural, 2-furaldehyde (2-F), formic acid, and acetic acid. Catalytic efficiency values of sulfuric acid for BH and OH were 21.58 and 8.35 g/g, respectively. Consequently, this study clearly indicates that the hydrolysates from the renewable resources can be used as feedstocks for the production of value-added products by biotechnological processes.
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