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1.
The kinetics of enzymatic hydrolysis of different lignocellulosic materials (wheat straw, newspaper and microcrystalline cellulose Avicel PH 101) was studied using the cellulase complexes from Trichoderma reesei QM 9414 and its mutants M 5, M 6, MHC 15 and MHC 22. The maximum yields of hydrolysis were obtained with wheat straw partially delignified with 1% NaOH as substrate, and using the enzyme from the mutants T. reesei M 6 and MHC 22. The possibility of simultaneous enzymatic hydrolysis and ethanol fermentation of wheat straw using the enzyme complex from M 6 and yeasts of the genus Candida and Torulopsis was also investigated. A good conversion of liberated glucose and cellobiose to ethanol was obtained, however, xylose was not fermented. 相似文献
2.
Enrique Cubas-Cano Cristina González-Fernández Mercedes Ballesteros Elia Tomás-Pejó 《Biotechnology progress》2019,35(1):e2739
Lactic acid is a versatile chemical that can be produced via fermentation of lignocellulosic materials. The heterolactic strain Lactobacillus pentosus CECT 4023 T, that can consume glucose and xylose, was studied to produce lactic acid from steam exploded wheat straw prehydrolysate. The effect of temperature and pH on bacterial growth was analyzed. Besides, the effect of oxygen on lactic acid production was tested and fermentation yields were compared in different scenarios. This strain showed very high tolerance to the inhibitors contained in the wheat straw prehydrolysate. The highest lactic acid yields based on present sugar, around 0.80 g g−1, were obtained from glucose in presence of 25%, 50%, and 75% v v−1 of prehydrolysate in strict anaerobiosis. Lactic fermentation of wheat straw hydrolysate obtained after enzymatic hydrolysis of the prehydrolysate yielded 0.39 g of lactic acid per gram of released sugars, which demonstrated the high potential of L. pentosus to produce lactic acid from hemicellulosic hydrolysates. Results presented herein not only corroborated the ability of L. pentosus to grow using mixtures of sugars, but also demonstrated the suitability of this strain to be applied as an efficient lactic acid producer in a lignocellulosic biorefinery approach. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2739, 2019 相似文献
3.
Prasad Kaparaju María Serrano Anne Belinda Thomsen Prawit Kongjan Irini Angelidaki 《Bioresource technology》2009,100(9):2562-2568
The production of bioethanol, biohydrogen and biogas from wheat straw was investigated within a biorefinery framework. Initially, wheat straw was hydrothermally liberated to a cellulose rich fiber fraction and a hemicellulose rich liquid fraction (hydrolysate). Enzymatic hydrolysis and subsequent fermentation of cellulose yielded 0.41 g-ethanol/g-glucose, while dark fermentation of hydrolysate produced 178.0 ml-H2/g-sugars. The effluents from both bioethanol and biohydrogen processes were further used to produce methane with the yields of 0.324 and 0.381 m3/kg volatile solids (VS)added, respectively. Additionally, evaluation of six different wheat straw-to-biofuel production scenaria showed that either use of wheat straw for biogas production or multi-fuel production were the energetically most efficient processes compared to production of mono-fuel such as bioethanol when fermenting C6 sugars alone. Thus, multiple biofuels production from wheat straw can increase the efficiency for material and energy and can presumably be more economical process for biomass utilization. 相似文献
4.
Succinic acid is a platform molecule that has recently generated considerable interests. Production of succinate from waste
orange peel and wheat straw by consolidated bioprocessing that combines cellulose hydrolysis and sugar fermentation, using
a cellulolytic bacterium, Fibrobacter succinogenes S85, was studied. Orange peel contains d-limonene, which is a well-known antibacterial agent. Its effects on batch cultures of F. succinogenes S85 were examined. The minimal concentrations of limonene found to inhibit succinate and acetate generation and bacterial
growth were 0.01%, 0.1%, and 0.06% (v/v), respectively. Both pre-treated orange peel by steam distillation to remove d-limonene and intact wheat straw were used as feedstocks. Increasing the substrate concentrations of both feedstocks, from
5 to 60 g/L, elevated succinate concentration and productivity but lowered the yield. In addition, pre-treated orange peel
generated greater succinate productivities than wheat straw but had similar resultant titres. The greatest succinate titres
were 1.9 and 2.0 g/L for pre-treated orange peel and wheat straw, respectively. This work demonstrated that agricultural waste
such as wheat straw and orange peel can be biotransformed to succinic acid by a one-step consolidated bioprocessing. Measures
to increase fermentation efficiency are also discussed. 相似文献
5.
Summary Lignin biodegradation, carbon loss and in vitro dry matter digestibility (IVDMD) have been investigated during the solid state fermentation of wheat straw by eight previously selected strains of white-rot fungi. A mathematical model of the degradation kinetics is presented. [The time period required to reach maximum rates of 14CO2 and unlabeled CO2 release from (14C)-lignin-labelled wheat straw and from whole wheat straw, respectively, was generally short (6–10 days).] High rates of 14C-lignin degradation were achieved by Pycnoporus cinnabarinus (2.9% 14CO2 evolved/day), an unidentified strain Nancon (3.0%/day), Sporotrichum pulverulentum Nov. (3.4%/day), Bjerkandera adusta (2.4%/day), and Dichomitus squalens (2.3%). However, only the latter two strains degraded whole wheat straw slowly and Bjerkandera adusta was not able to degrade more than 23% of the 14C-lignin.
Cyathus stercoreus and Dichomitus squalens facilitated the highest improvement in IVDMD (68% against 38% for the sound straw) after 20 and 15 days of cultivation respectively, with low dry matter losses (15–20%). A study of the fate of 14C-lignin during fermentation using these two fungal strains showed that maximal levels of (14C)-water-soluble compounds are reached before peak levels of 14CO2 evolution suggesting that these compounds are intermediates in lignin degradation. A possible relationship between water-soluble lignins and IVDMD improvement is discussed. 相似文献
6.
Simultaneous saccharification and fermentation (SSF) is one process option for production of ethanol from lignocellulose.
The principal benefits of performing the enzymatic hydrolysis together with the fermentation, instead of in a separate step
after the hydrolysis, are the reduced end-product inhibition of the enzymatic hydrolysis, and the reduced investment costs.
The principal drawbacks, on the other hand, are the need to find favorable conditions (e.g. temperature and pH) for both the enzymatic hydrolysis and the fermentation and the difficulty to recycle the fermenting
organism and the enzymes. To satisfy the first requirement, the temperature is normally kept below 37°C, whereas the difficulty
to recycle the yeast makes it beneficial to operate with a low yeast concentration and at a high solid loading. In this review,
we make a brief overview of recent experimental work and development of SSF using lignocellulosic feedstocks. Significant
progress has been made with respect to increasing the substrate loading, decreasing the yeast concentration and co-fermentation
of both hexoses and pentoses during SSF. Presently, an SSF process for e.g. wheat straw hydrolyzate can be expected to give final ethanol concentrations close to 40 g L-1 with a yield based on total hexoses and pentoses higher than 70%. 相似文献
7.
Bioconversion of wheat straw to ethanol: Chemical modification,enzymatic hydrolysis,and fermentation
R. W. Detroy L. A. Lindenfelser S. Sommer W. L. Orton 《Biotechnology and bioengineering》1981,23(7):1527-1535
Native wheat straw (WS) was pretreated with various concentrations of H2SO4 and NaOH followed by secondary treatments with ethylene diamine (EDA) and NH4OH prior to enzymatic saccharification. Conversion of the cellulosic component to sugar varied with the chemical modification steps. Treatment solely with alkali yield 51–75% conversion, depending on temperature. Acid treatment at elevated tempeatures showed a substantial decrease in the hemicellulose component, whereas EDA-treated WS (acid pretreated) showed a 69–75% decrease in the lignin component. Acid-pretreated EDA-treated straw yielded a 98% conversion rate, followed by 83% for alkali–NH4OH treated straws. In other experiments, WS was pretreated with varying concentration of H2SO4 or NaOh followed by NH4OH treatment prior to enzymatic hydrolysis. Pretreatment of straw with 2% NaOH for 4 h coupled to enzymatic hydrolysis yield a 76% conversion of the cellulosic component. Acid–base combination pretreatment yielded only 43% conversions. A reactor column was subsequently used to measure modification–saccharification–fermentation for wheat straw conversion on a larger scale. Thirty percent conversions of wheat straw cellulosics to sugar were observed with subsequent fermentation to alcohol. The crude cellulase preparation yielded considerable quantities of xylose in addition to the glucose. Saccharified materials were fermented directly with actively proliferating proliferating yeast cells without concentration of the sugars. 相似文献
8.
J. Szczodrak 《Engineering in Life Science》1988,8(6):509-515
Autohydrolyzed and ethanol-alkali pulped wheat straw was examined as a candidate feedstock for both cellulase and xylanase production and enzymatic hydrolysis. Submerged cultures of Trichoderma reesei F-522 grown on hydrothermally modified straw provided culture supernatants of the highest enzymatic activities, whereas the maximal efficiency of enzymatic hydrolysis was recorded in straw treated with ethanol-NaOH mixture. Some culture conditions were optimized to improve the growth and cellulase production by T. reesei on autohydrolyzed wheat straw. 相似文献
9.
The production of extracellular xylanase by a locally isolated strain of Aspergillus tubingensis JP-1 was studied under solid-state fermentation. Among the various agro residues used wheat straw was found to be the best
for high yield of xylanase with poor cellulase production. The influence of various parameters such as initial pH, moisture,
moistening agents, nitrogen sources, additives, surfactants and pretreatment of substrates were investigated. The production
of the xylanase reached a peak in 8 days using untreated wheat straw with modified MS medium, pH 6.0 at 1:5 moisture level
at 30 °C. Under optimized conditions yield as high as 6,887 ± 16 U/g of untreated wheat straw was achieved. Crude xylanase
was used for enzymatic saccharification of agro-residues like wheat straw, rice bran, wheat bran, sugarcane bagasse and industrial
paper pulp. Dilute alkali (1 N NaOH) and acid (1 N H2SO4) pretreatment were found to be beneficial for the efficient enzymatic hydrolysis of wheat straw. Dilute alkali and acid-pretreated
wheat straw yielded 688 and 543 mg/g reducing sugar, respectively. Yield of 726 mg/g reducing sugar was obtained from paper
pulp after 48 h of incubation. 相似文献
10.
Summary Uniformly14C labelled glucose, cellulose and wheat straw and specifically14C labelled lignin component in corn stalks were aerobically incubated for 12 weeks in a chernozem soil alongwith15N labelled ammonium sulphate. Glucose was most readily decomposed, followed in order by cellulose, wheat straw and corn stalk lignins labelled at methoxyl-, side chain 2-and ring-C. More than 50% of14C applied as glucose, cellulose and wheat straw evolved as CO2 during the first week. Lignin however, decomposed relatively slowly. A higher proportion of14C was transformed into microbial biomass whereas lignins contributed a little to this fraction.After 12 weeks of incubation nearly 60% of the lignin14C was found in humic compounds of which more than 70% was resistant to hydrolysis with 6N HCl. Maximum incorporation of15N in humic compounds was observed in cellulose amended soil. However, in this case more than 80% of the15N was in hydrolysable forms.Immobilization-remineralization of applied15N was most rapid in glucose treated soil and a complete immobilization followed by remineralization was observed after 3 days. The process was much slow in soil treated with cellulose, wheat straw or corn stalks. More than 70% of the newly immobilized N was in hydrolysable forms mainly reepresenting the microbial component.Serial hydrolysis of soil at different incubation intervals showed a greater proportion of 6N HCl hydrolysable14C and15N in fractions representing microbial material.14C from lignin carbons was relatively more uniformly distributed in different fractions as compared to glucose, cellulose and wheat straw where a major portion of14C was in easily hydrolysable fractions. 相似文献
11.
Succinic acid production from wheat using a biorefining strategy 总被引:2,自引:0,他引:2
The biosynthesis of succinic acid from wheat flour was investigated in a two-stage bio-process. In the first stage, wheat
flour was converted into a generic microbial feedstock either by fungal fermentation alone or by combining fungal fermentation
for enzyme and fungal bio-mass production with subsequent flour hydrolysis and fungal autolysis. In the second stage, the
generic feedstock was converted into succinic acid by bacterial fermentation by Actinobacillus succinogenes. Direct fermentation of the generic feedstock produced by fungal fermentation alone resulted in a lower succinic acid production,
probably due to the low glucose and nitrogen concentrations in the fungal broth filtrate. In the second feedstock production
strategy, flour hydrolysis conducted by mixing fungal broth filtrate with wheat flour generated a glucose-rich stream, while
the fungal bio-mass was subjected to autolysis for the production of a nutrient-rich stream. The possibility of replacing
a commercial semi-defined medium by these two streams was investigated sequentially. A. succinogenes fermentation using only the wheat-derived feedstock resulted in a succinic acid concentration of almost 16 g l–1 with an overall yield of 0.19 g succinic acid per g wheat flour. These results show that a wheat-based bio-refinery employing
coupled fungal fermentation and subsequent flour hydrolysis and fungal autolysis can lead to a bacterial feedstock for the
efficient production of succinic acid. 相似文献
12.
Bhuvnesh Shrivastava Shilpi Thakur Yogender Pal Khasa Akshaya Gupte Anil Kumar Puniya Ramesh Chander Kuhad 《Biodegradation》2011,22(4):823-831
In order to improve the digestibility and nutrient availability in rumen, wheat straw was subjected to solid state fermentation
(SSF) with white-rot fungi (i.e. Pleurotus ostreatus and Trametes versicolor) and the fermented biomass (called myco-straw) was evaluated for biochemical, enzymatic and nutritional parameters. The fungal
treatment after 30 days led to significant decrease (P < 0.05) in cell wall constituents viz, acid detergent fiber (ADF), neutral detergent fiber (NDF), hemicellulose, lignin and
cellulose to the extent of 35.00, 38.88, 45.00, 37.48 and 37.86%, respectively in P. ostreatus fermented straw, while 30.04, 33.85, 39.90, 31.29 and 34.00%, respectively in T. versicolor fermented straw. However, maximum efficiency of fermentation in terms of low carbohydrate consumption per unit of lignin
degradation, favoring cattle feed production was observed for P. ostreatus on the 10th day (17.12%) as compared with T. versicolor on the 30th day (16.91%). The myco-straw was found to contain significantly high (P < 0.05) crude protein (CP; 4.77% T. versicolor, 5.08% P. ostreatus) as compared to control straw (3.37%). Metabolizable energy (ME, MJ/kg DM), percent organic matter digestibility (OMD) and
short chain fatty acids (SCFAs; mmol) production also increased considerably from control straw (4.40, 29.91 and 0.292) to
a maximum up to P. ostreatus fermented straw (4.92, 33.39 and 0.376 on 20th day) and T. versicolor fermented straw (4.66, 31.74 and 0.334 on 10th day), respectively. Moreover, the myco-straw had lower organic carbon and
was rich in nitrogen with lower C/N ratio as compared to control wheat straw. Results suggest that the fungal fermentation
of wheat straw effectively improved CP content, OM digestibility, SCFAs production, ME value and simultaneously lowered the
C/N ratio, thus showing potential for bioconversion of lignin rich wheat straw into high energy cattle feed. 相似文献
13.
Comparison of SHF and SSF processes for the bioconversion of steam-exploded wheat straw 总被引:6,自引:0,他引:6
F Alfani A Gallifuoco A Saporosi A Spera M Cantarella 《Journal of industrial microbiology & biotechnology》2000,25(4):184-192
Two processes for ethanol production from wheat straw have been evaluated — separate hydrolysis and fermentation (SHF) and
simultaneous saccharification and fermentation (SSF). The study compares the ethanol yield for biomass subjected to varying
steam explosion pretreatment conditions: temperature and time of pretreatment was 200°C or 217°C and at 3 or 10 min. A rinsing
procedure with water and NaOH solutions was employed for removing lignin residues and the products of hemicellulose degradation
from the biomass, resulting in a final structure that facilitated enzymatic hydrolysis. Biomass loading in the bioreactor
ranged from 25 to 100 g l−1 (dry weight). The enzyme-to-biomass mass ratio was 0.06. Ethanol yields close to 81% of theoretical were achieved in the
two-step process (SHF) at hydrolysis and fermentation temperatures of 45°C and 37°C, respectively. The broth required addition
of nutrients. Sterilisation of the biomass hydrolysate in SHF and of reaction medium in SSF can be avoided as can the use
of different buffers in the two stages. The optimum temperature for the single-step process (SSF) was found to be 37°C and
ethanol yields close to 68% of theoretical were achieved. The SSF process required a much shorter overall process time (≈30
h) than the SHF process (96 h) and resulted in a large increase in ethanol productivity (0.837 g l−1 h−1 for SSF compared to 0.313 g l−1 h−1 for SHF). Journal of Industrial Microbiology & Biotechnology (2000) 25, 184–192.
Received 02 December 1999/ Accepted in revised form 20 July 2000 相似文献
14.
Assembly of mutations for improving thermostability of <Emphasis Type="Italic">Escherichia coli</Emphasis> AppA2 phytase 总被引:2,自引:0,他引:2
Maas RH Bakker RR Jansen ML Visser D de Jong E Eggink G Weusthuis RA 《Applied microbiology and biotechnology》2008,79(5):751-758
Conventional processes for lignocellulose-to-organic acid conversion requires pretreatment, enzymatic hydrolysis, and microbial
fermentation. In this study, lime-treated wheat straw was hydrolyzed and fermented simultaneously to lactic acid by an enzyme
preparation and Bacillus coagulans DSM 2314. Decrease in pH because of lactic acid formation was partially adjusted by automatic addition of the alkaline substrate.
After 55 h of incubation, the polymeric glucan, xylan, and arabinan present in the lime-treated straw were hydrolyzed for
55%, 75%, and 80%, respectively. Lactic acid (40.7 g/l) indicated a fermentation efficiency of 81% and a chiral l(+)-lactic acid purity of 97.2%. In total, 711 g lactic acid was produced out of 2,706 g lime-treated straw, representing
43% of the overall theoretical maximum yield. Approximately half of the lactic acid produced was neutralized by fed-batch
feeding of lime-treated straw, whereas the remaining half was neutralized during the batch phase with a Ca(OH)2 suspension. Of the lime added during the pretreatment of straw, 61% was used for the neutralization of lactic acid. This
is the first demonstration of a process having a combined alkaline pretreatment of lignocellulosic biomass and pH control
in fermentation resulting in a significant saving of lime consumption and avoiding the necessity to recycle lime. 相似文献
15.
N. Nayan A.S.M. Sonnenberg W.H. Hendriks J.W. Cone 《Journal of applied microbiology》2018,125(2):468-479
Aim
In this study, the biological variation for improvement of the nutritive value of wheat straw by 12 Ceriporiopsis subvermispora, 10 Pleurotus eryngii and 10 Lentinula edodes strains was assessed. Screening of the best performing strains within each species was made based on the in vitro degradability of fungal‐treated wheat straw.Methods and Results
Wheat straw was inoculated with each strain for 7 weeks of solid state fermentation. Weekly samples were evaluated for in vitro gas production (IVGP) in buffered rumen fluid for 72 h. Out of the 32 fungal strains studied, 17 strains showed a significantly higher (P < 0·05) IVGP compared to the control after 7 weeks (227·7 ml g?1 OM). The three best Ceriporiopsis subvermispora strains showed a mean IVGP of 297·0 ml g?1 OM, while the three best P. eryngii and L. edodes strains showed a mean IVGP of 257·8 and 291·5 ml g?1 OM, respectively.Conclusion
Ceriporiopsis subvermispora strains show an overall high potential to improve the ruminal degradability of wheat straw, followed by L. edodes and P. eryngii strains.Significance and Impact of the Study
Large variation exists within and among different fungal species in the valorization of wheat straw, which offers opportunities to improve the fungal genotype by breeding. 相似文献16.
Decomposition of Lignocellulose by Cyathus stercoreus (Schw.) de Toni NRRL 6473, a “White Rot” Fungus from Cattle Dung
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Cyathus stercoreus (Schw.) de Toni NRRL 6473, isolated from aged and fragmented cattle dung collected from a Michigan pasture, effected substantial losses in lignin (45%) from wheat straw during a 62-day fermentation (25°C). The basidiomycete also improved wheat straw digestibility by freeing α-cellulose for enzymatic hydrolysis to glucose (230 mg of glucose per 1,000 mg of fermented residue). The rationale for selecting C. stercoreus in attempting to biologically modify the lignin and cellulose components in wheat straw or other gramineous agricultural residues was based on the expectation that this organism is ecologically specialized to enzymatically attack the substructures of native lignins in grasses. 相似文献
17.
M. I. Rajoka Tayyaba Huma A. M. Khalid F. Latif 《World journal of microbiology & biotechnology》2005,21(6-7):869-876
Summary Industrial byproducts namely canola meal, rice bran, sunflower meal, and wheat straw were used as substrates for endo-xylanase
production by Humicola lanuginosemutant TH1 through solid substrate fermentation. The enzyme was secreted extracellularly by both wild and mutant cultures.
Rice bran supported the maximum production of endo-xylanase followed by wheat straw, canola meal and sunflower meal. The highest
activity was achieved after 72 h of culture and the highest yields from the above substrates were 842, 840, 610 and 608 IU
per g substrate consumed respectively. The highest productivity (281 IU flask−1 h−1 corresponding to 5620 l−1 h-1) of endo-xylanase by the mutant of H. lanuginosa was 1.6-fold more than that produced by the parental organism in solid-state fermentation of rice bran at 45 °C. Maximum
specific activity (180 IU mg−1 protein) and substrate consumption rates were significantly more than those reported by previous researchers on Humicola sp. The mutant possessed markedly low accompanying cellulase activity. Thermodynamic studies revealed that the mutant required
significantly lower activation energy for enzyme production and higher for thermal inactivation which signified that the endogenous
metabolic machinery of mutant cells exerted more protection against thermal inactivation during product formation than that
needed by its parental cultures. 相似文献
18.
Alfredo Oliva‐Taravilla Elia Tomás‐Pejó Marie Demuez Cristina González‐Fernández Mercedes Ballesteros 《Biotechnology progress》2015,31(3):700-706
The presence of inhibitors compounds after pretreatment of lignocellulosic materials affects the saccharification and fermentation steps in bioethanol production processes. Even though, external addition of laccases selectively removes the phenolic compounds from lignocellulosic prehydrolysates, when it is coupled to saccharification step, lower hydrolysis yields are attained. Vanillin, syringaldehyde and ferulic acid are phenolic compounds commonly found in wheat‐straw prehydrolysate after steam‐explosion pretreatment. These three phenolic compounds were used in this study to elucidate the inhibitory mechanisms of laccase‐derived compounds after laccase treatment. Reaction products derived from laccase oxidation of vanillin and syringaldehyde showed to be the strongest inhibitors. The presence of these products causes a decrement on enzymatic hydrolysis yield of a model cellulosic substrate (Sigmacell) of 46.6 and 32.6%, respectively at 24 h. Moreover, a decrease in more than 50% of cellulase and β‐glucosidase activities was observed in presence of laccase and vanillin. This effect was attributed to coupling reactions between phenoxyl radicals and enzymes. On the other hand, when the hydrolysis of Sigmacell was performed in presence of prehydrolysate from steam‐exploded wheat straw a significant inhibition on enzymatic hydrolysis was observed independently of laccase treatment. This result pointed out that the other components of wheat‐straw prehydrolysate are affecting the enzymatic hydrolysis to a higher extent than the possible laccase‐derived products. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:700–706, 2015 相似文献
19.
In order to increase the eco-efficiency and overall availability of naturally renewable resource, the novel bioconversion
of steam-exploded wheat straw to bio-organic fertilizer containing N2-fixer, P and K solubilizers was investigated. The conversion was performed in solid-state fermentation (SSF) with periodic
air-forced pressure oscillation (PAPO). The results showed that SSF-PAPO was competitive with the conventional solid-state
fermentation (cSSF) in biomass accumulation and wheat straw digestion. With solid–liquid ratio 1:3, microbial biomass production
at 72 h was high up to 2 × 1011 cfu g−1, nearly twice as that in cSSF. The degradation rate of cellulose, hemicellulose and lignin after fermentation in SSF-PAPO
reached 48.57 ± 10.66, 84.77 ± 2.75 and 2.15 ± 10.11, respectively, which was greater than that of 29.30 ± 10.28%, 33.47 ± 4.85%
and 0.53 ± 9.07% in cSSF, correspondingly. The SSF-PAPO system displayed unique advantage, by a novel gas phase control strategy
on gas concentration and heat gradient, on the bioconversion of wheat straw to the bio-organic fertilizer. 相似文献
20.
Katarzyna Robak Maria Balcerek Urszula Dziekońska-Kubczak Piotr Dziugan 《Biotechnology progress》2019,35(3):e2789
This research shows the effect of dilute acid pretreatment with various sulfuric acid concentrations (0.5–2.0% [wt/vol]) on enzymatic saccharification and fermentation yield of rye straw. After pretreatment, solids of rye straw were suspended in Na citrate buffer or post-pretreatment liquids (prehydrolysates) containing sugars liberated after hemicellulose hydrolysis. Saccharification was conducted using enzymes dosage of 15 or 25 FPU/g cellulose. Cellulose saccharification rate after rye straw pretreatment was enhanced by performing enzymatic hydrolysis in sodium citrate buffer in comparison with hemicellulose prehydrolysate. The maximum cellulose saccharification rate (69%) was reached in sodium citrate buffer (biomass pretreated with 2.0% [wt/vol] H2SO4). Lignocellulosic complex of rye straw after pretreatment was subjected to separate hydrolysis and fermentation (SHF) or separate hydrolysis and co-fermentation (SHCF). The SHF processes conducted in the sodium citrate buffer using monoculture of Saccharomyces cerevisiae (Ethanol Red) were more efficient compared to hemicellulose prehydrolysate in respect with ethanol yields. Maximum fermentation efficiency of SHF processes obtained after rye straw pretreatment at 1.5% [wt/vol] H2SO4 and saccharification using enzymes dosage of 25 FPU/g in sodium citrate buffer, achieving 40.6% of theoretical yield. However, SHCF process using cocultures of pentose-fermenting yeast, after pretreatment of raw material at 1.5% [wt/vol] H2SO4 and hydrolysis using enzymes dosage of 25 FPU/g, resulted in the highest ethanol yield among studied methods, achieving 9.4 g/L of ethanol, corresponding to 55% of theoretical yield. 相似文献