Onsite bio-detoxification of steam-exploded corn stover for cellulosic ethanol production

In the process of ethanol production from steam-exploded corn stover (SECS), a cellulose-degradation strain of Aspergillus nidulans (FLZ10) was investigated whether it could remove the inhibitors released from steam exploded pretreatment , and thereby be used for biological detoxification on Saccharomycescerevisiae. The results showed that FLZ10 removed 75.2% formic acid, 53.6% acetic acid, and 100% hydroxymethyl furfural (5-HMF) and furfural from the hydrolysate washed from SECS after 72 h cultivation. A cellulase activity of 0.49 IU/ml was simultaneously produced while the biological detoxification occurred. An ethanol yield of 0.45 g/g on glucose was obtained in the hydrolysate biodetoxified by FLZ10. The glucose consumption rate of FLZ10 was much lower than that of S. cerevisiae, thereby it had little competition with S. cerevisiae on glucose consumption. Based on SECS to ethanol mass balance analysis, with the onsite bio-detoxification, fermentation using S. cerevisiae effectively converted monomeric glucose with 94.4% ethanol yield.     

Simultaneous saccharification and fermentation of steam-exploded corn stover at high glucan loading and high temperature

Background

Simultaneous saccharification and fermentation (SSF) is a promising process for bioconversion of lignocellulosic biomass. High glucan loading for hydrolysis and fermentation is an efficient approach to reduce the capital costs for bio-based products production. The SSF of steam-exploded corn stover (SECS) for ethanol production at high glucan loading and high temperature was investigated in this study.

Results

Glucan conversion of corn stover biomass pretreated by steam explosion was maintained at approximately 71 to 79% at an enzyme loading of 30 filter paper units (FPU)/g glucan, and 74 to 82% at an enzyme loading of 60 FPU/g glucan, with glucan loading varying from 3 to 12%. Glucan conversion decreased obviously with glucan loading beyond 15%. The results indicated that the mixture was most efficient in enzymatic hydrolysis of SECS at 3 to 12% glucan loading. The optimal SSF conditions of SECS using a novel Saccharomyces cerevisiae were inoculation optical density (OD)₆₀₀?=?4.0, initial pH 4.8, 50% nutrients added, 36 hours pre-hydrolysis time, 39°C, and 12% glucan loading (20% solid loading). With the addition of 2% Tween 20, glucan conversion, ethanol yield, final ethanol concentration reached 78.6%, 77.2%, and 59.8 g/L, respectively, under the optimal conditions. The results suggested that the solid and degradation products’ inhibitory effect on the hydrolysis and fermentation of SECS were also not obvious at high glucan loading. Additionally, glucan conversion and final ethanol concentration in SSF of SECS increased by 13.6% and 18.7%, respectively, compared with separate hydrolysis and fermentation (SHF).

Conclusions

Our research suggested that high glucan loading (6 to 12% glucan loading) and high temperature (39°C) significantly improved the SSF performance of SECS using a thermal- and ethanol-tolerant strain of S. cerevisiae due to the removal of degradation products, sugar feedback, and solid’s inhibitory effects. Furthermore, the surfactant addition obviously increased ethanol yield in SSF process of SECS.

     

Improved efficiency of separate hexose and pentose fermentation from steam-exploded corn stalk for butanol production using <Emphasis Type="Italic">Clostridium beijerinckii</Emphasis>

Water extract of steam-exploded corn stalk (SECS) was detoxified and used as feed for acetone–butanol–ethanol (ABE) fermentation using Clostridium beijerinckii. Utilization of water extract improved the total ABE yield (g ABE/g dry SECS). Separated fermentation showed higher fermentability (0.078 g ABE/g dry SECS) over typical fermentation (0.058 g ABE/g dry SECS). Furthermore, the final ABE yields (g ABE/g utilized sugar) from water extract neutralized by Ca(OH)₂, NaOH, and Na₂SO₃ were 0.16, 0.1 and 0.07, respectively, suggesting that Ca(OH)₂ had the best detoxification effect.     

玻璃粉吸附核酸及其在植物核酸提取中应用的研究

为研究玻璃粉在植物核酸提取中的应用,比较了玻璃粉颗粒大小、离液盐种类及浓度、pH等条件对玻璃粉吸附核酸的影响,得出玻璃粉吸附核酸的各种最佳条件。结果表明,普通玻璃粉吸附核酸能力强于硅胶和硅藻土,玻璃粉颗粒的直径以83 μm为佳,pH 4.0时吸附效果达到最大。提取DNA时,NaCl浓度应大于3 mol/L,而提取RNA时,异硫氰酸胍大于2 mol/L就能取得很好的效果,此外,在玻璃粉吸附RNA前,需要加入50%以上的无水乙醇才能更好地吸附。利用玻璃粉制作简易纯化柱,可用于植物组织核酸提取纯化,所提取的核酸纯度高、完整性好,可用于酶切、杂交和PCR等实验。与传统方法相比,采用玻璃粉简易离心柱提取植物核酸,效果好、环保、快速、经济。     

Leaf optical properties of an alpine perennial herbSelinum vaginatum clarke grown at two altitudes

The absorptivity of the leaves at all the wavelengths decreased whereas the reflectivity and transmissivity increased when an alpine perennial herb, Selinum vaginatum was grown at lower (550 m) elevation. The lower elevation climate modified leaves to absorb comparatively less near-infrared radiation as compared to that under natural habitat. The lower altitude habitat had a positive effect on infinite reflectance and a negative effect on absorption and scattering coefficients of the leaves. Based on the scattering and absorption coefficients for upper and lower leaf surfaces, the ‘sieve’ and ‘detour’ effect factors were estimated. These factors indicate that while ‘sieve-effect’ increases the ‘detour-effect’ decreases when this plant is grown at lower elevation. This explains lower light absorption (PAR) in this plant when grown at lower elevation. For survival under the habitat with high thermal load the leaves of this alpine herb could maintain lower temperature by way of reduced absorption in near-infrared radiation region which probably is accomplished by lower water contents and thickness of leaves at lower elevation.     

Usefulness of raw bagasse for oil absorption: A comparison of raw and acylated bagasse and their components

Raw bagasse or sugar cane cellulosic residues were modified using acylation grafting with fatty acid. The capability of the grafted bagasse to absorb oil from aqueous solution was studied and compared with the raw bagasse. It was found that the grafted material was significantly more hydrophobic than the raw bagasse. This grafted bagasse had little affinity for water and good affinity for oil. It was also found that bleaching of raw bagasse did not enhance its oil absorptivity. The grafted raw bagasse would be most suitable for applications where oil is to be removed from an aqueous environment. For oil absorbing applications in the absence of water, the raw bagasse was an excellent material.     

Ethanol inhibition of phencyclidine percutaneous absorption

The effect of parenterally administered ethanol on the percutaneous absorption of phencyclidine hydrochloride was investigated using the intact hairless (SKH, hr?1/hr?1) mouse as a model. Four hours after topical application of phencyclidine hydrochloride, the mean phencyclidine concentration (129.2 ng/g) in excised liver was significantly lower in mice that had received ethanol by intraperitoneal injection than in mice injected intraperitoneally with water (1730.1 ng/g) (p < 0.01). When phencyclidine hydrochloride was administered by intraperitoneal injection there was no statistically significant difference between the mean concentration in liver (3442.5 ng/g) for ethanol-treated mice and that (3030.3 ng/g) for the control mice (p > 0.10), indicating that the observed difference was not due to enhancement of phencyclidine metabolism by ethanol. These findings suggest that ethanol inhibits the percutaneous absorption of phencyclidine hydrochloride.     

Adaptations to foliar absorption of faeces: a pathway in plant carnivory

BACKGROUND AND AIMS: Roridula plants capture insects but have no digestive enzymes. It has been hypothesized that Roridula leaves absorb nitrogen from the faeces of obligately associated, carnivorous hemipterans. But rapid movement across the leaf surfaces of most plant leaves is prevented by the presence of an impermeable cuticle. However, in carnivorous plants, cuticular gaps or pores in digestive/absorptive cells allow rapid movement across the leaf surface. Recently, it was suggested that the hemipteran-plant interaction constituted a new pathway for plant carnivory. Here, a further adaptation to this pathway is described by demonstrating how Roridula plants probably absorb hemipteran faeces rapidly through their leaf cuticles. METHODS: The dye neutral red was used to document the rapidity of foliar absorption and TEM to determine the nature of cuticular discontinuities in the leaf of Roridula. KEY RESULTS: Aqueous compounds diffuse rapidly across the cuticle of Roridula's leaves but not across the cuticles of co-occurring, non-carnivorous plant leaves. Furthermore, immature Roridula leaves were unable to absorb neutral red whereas mature leaves could. Using TEM, cuticular gaps and pores similar to those in other carnivorous plants were found in the epidermal cells of mature Roridula leaves. CONCLUSIONS: The leaf cuticle of Roridula is very thin (0-120 nm) and cell wall elements project close to the leaf surface, possibly enhancing foliar absorption. In addition to these, cuticular gaps were frequently seen and probably perform a function similar to those found in other carnivorous plants: namely the absorption of aqueous compounds. The cuticular gaps of Roridula are probably an adaptation to plant carnivory, supporting the newly described pathway.     

乙醇脱氢酶（ADH）产酶菌株的选育

从食醋生产企业的醋醅中采集样品,以乙醇为唯一碳源,用碳酸钙透明圈平板法分离出185株菌株,然后以产酸量和耐乙醇能力为标准,瓶发酵选育出20株ADH产酶菌株;A5-2产酸量为49.85 g/L,耐乙醇能力强,A5-2的菌种形态学和16S rDNA序列分析初步鉴定为巴斯德醋酸杆菌（ Acetobacter pasteurianus）;A5-2乙醇脱氢酶酶学性质研究表明：最适作用温度和pH分别为45℃和pH 4.0,具有一定的耐热性和良好的耐酸碱性;A5-2乙醇脱氢酶粗酶制备条件为硫酸铵饱和度70%~80%,回收率84%。     

Effect of inhibitors formed during wheat straw pretreatment on ethanol fermentation by Pichia stipitis

The inhibitory effect of the main inhibitors (acetic acid, furfural and 5-hydroxymethylfurfural) formed during steam explosion of wheat straw was studied through ethanol fermentations of model substrates and hydrolysates from wheat straw by Pichia stipitis. Experimental results showed that an increase in acetic acid concentration led to a reduction in ethanol productivity and complete inhibition was observed at 3.5 g/L. Furfural produced a delay on sugar consumption rates with increasing concentration and HMF did not exert a significant effect. Fermentations of the whole slurry from steam exploded wheat straw were completely inhibited by a synergistic effect due to the presence of 1.5 g/L acetic acid, 0.15 g/L furfural and 0.05 g/L HMF together with solid fraction. When using only the solid fraction from steam explosion, hydrolysates presented 0.5 g/L of acetic acid, whose fermentations have submitted promising results, providing an ethanol yield of 0.45 g ethanol/g sugars and the final ethanol concentration reached was 12.2 g/L (10.9 g ethanol/100 g DM).     

Production of ethanol directly from potato starch by mixed culture of Saccharomyces cerevisiae and Aspergillus niger using electrochemical bioreactor

When cultivated aerobically, Aspergillus niger hyphae produced extracellular glucoamylase, which catalyzes the saccharification of unliquified potato starch into glucose, but not when grown under anaerobic conditions. The Km and Vmax of the extracellular glucoamylase were 652.3 mg starch l-1 and 253.3 mg glucose l-1 min-1, respectively. In mixed culture of A. niger and Saccharomyces cerevisiae, oxygen had a negative influence on the alcohol fermentation of yeast, but activated fungal growth. Therefore, oxygen is a critical factor for ethanol production in the mixed culture, and its generation through electrolysis of water in an electrochemical bioreactor needs to be optimized for ethanol production from starch by coculture of fungal hyphae and yeast cells. By applying pulsed electric fields (PEF) into the electrochemical bioreactor, ethanol production from starch improved significantly: Ethanol produced from 50 g potato starch l-1 by a mixed culture of A. niger and S. cerevisiae was about 5 g l-1 in a conventional bioreactor, but was 9 g l-1 in 5 volts of PEF and about 19 g l-1 in 4 volts of PEF for 5 days.     

Polystichum munitum (Dryopteridaceae) varies geographically in its capacity to absorb fog water by foliar uptake within the redwood forest ecosystem

? Premise of the study: Fog provides a critical water resource to plants around the world. In the redwood forest ecosystem of northern California, plants depend on fog absorbed through foliar uptake to stay hydrated during the rainless summer. In this study, we identified regions within the redwood ecosystem where the fern Polystichum munitum canopy most effectively absorbs fog drip that reaches the forest floor. ? Methods: We measured the foliar uptake capacity of P. munitum fronds at seven sites along 700 km of the redwood forest ecosystem. We quantified the canopy cover of P. munitum at each site and estimated how much water the fern canopy can acquire aboveground through fog interception and absorption. ? Key results: Throughout the ecosystem, nocturnal foliar uptake increased the leaf water content of P. munitum by 7.2%, and we estimated that the P. munitum canopy can absorb 5 ± 3% (mean ± SE) of intercepted fog precipitation. Strikingly, P. munitum had the highest foliar uptake capacity in the center of the ecosystem and may absorb 10% more of the fog its canopy intercepts in this region relative to other regions studied. Conversely, P. munitum had no foliar uptake capacity in the southern end of the ecosystem. ? Conclusions: This study shows the first evidence that foliar uptake varies within species at the landscape scale. Our findings suggest that the P. munitum at the southern tip of the redwood ecosystem may suffer most from low summertime water availability because it had no potential to acquire fog as an aboveground water subsidy.     

Sugar uptake and translocation in the castor bean seedling I. Characteristics of transfer in intact and excised seedlings

Changes in the dry weights of various parts of the castor bean seedling showed that the rates of transfer of material through the cotyledons to the embryonic axis exceeded 2 mg/hour after 5 to 6 days of germination. The sugar present in the endosperm was predominantly, and in the cotyledon almost exclusively, sucrose. Anatomical features were described which contribute to the efficiency of the cotyledons as organs of absorption and transmittal of sucrose to the embryonic axis, where hexoses are much more prevalent.The ability of the cotyledons to absorb sucrose survived removal of the endosperm from the seedling. A series of experiments is described in which the cotyledons of such excised seedlings were immersed in sucrose-(14)C and measurements made of uptake and of translocation to various parts of the seedling. Increasing rates of absorption were observed as the sucrose concentration was raised to 0.5 m and these rates were maintained for several hours. Removal of the embryonic axis (hypocotyl plus roots) drastically altered both the response to sucrose concentration and the time course of absorption by the cotyledons.More than 80% of the sugar normally entering the cotyledons from the endosperm is transmitted to the embryonic axis and this extensive turnover was seen also in pulse/chase experiments with excised seedlings. The cotyledons of excised seedlings absorbed sucrose against high apparent concentration gradients. The absorption was stimulated by phosphate and had a pH optimum at about pH 6.4. It was inhibited by arsenate, azide and 2,4-dinitrophenol.     

Development of xylose-fermenting yeast Pichia stipitis for ethanol production through adaptation on hardwood hemicellulose acid prehydrolysate

AIMS: The objective of this study was to develop a mutant from Pichia stipitis NRRL Y-7124, tolerant of high concentrations of acetic acid and other inhibitory components present in acid hydrolysates, to improve ethanol yield and productivity. METHODS AND RESULTS: The mutant was developed through adaptation in acid hydrolysate supplemented with nutrients and minerals at 30 +/- 0.5 degrees C. When it was tested for its ability to ferment acid hydrolysate, it showed shorter fermentation time, better tolerance to acid and could ferment at lower pH. The ethanol yield (Yp/s) and productivity (Qp) were increased 1.6- and 2.1-fold, respectively. CONCLUSION: The development of a mutant and its tolerance to acetic acid present in hydrolysates is described. The selected mutant is capable of fermenting both hexoses and pentoses present in hydrolysate at lower pH in comparison with the parent strain. SIGNIFICANCE AND IMPACT OF THE STUDY: The mutant could play a significant role in reducing environmental pollution by using sugars present in pulp mill effluent and, at the same time, could produce a marketable liquid fuel ethanol.     

Ethanol fermentation of acid-hydrolyzed cellulosic pyrolysate with Saccharomyces cerevisiae

Acid-hydrolysis of cellulosic pyrolysate to glucose and its fermentation to ethanol were investigated. The maximum glucose yield (17.4%) was obtained by the hydrolysis with 0.2 mol/l sulfuric acid using autoclaving at 121 degrees C for 20 min. The fermentation by Saccharomyces cerevisiae of a hydrolysate medium containing 31.6 g/l glucose gave 14.2 g/l ethanol after 24 h, whereas the fermentation of the medium containing 31.6 g/l pure glucose gave 13.7 g/l ethanol after 18 h. The results showed that acid-hydrolyzed pyrolysate could be used for ethanol production. Different nitrogen sources were evaluated and the best ethanol concentration (15.1 g/l) was achieved by single urea. S. cerevisiae (R) was obtained by adaptation of S. cerevisiae to the hydrolysate medium for 12 times, and 40.2 g/l ethanol was produced by it in the fermentation with the hydrolysate medium containing 95.8 g/l glucose, which was about 47% increase in ethanol production compared to its parent strain.     

Determination of ethanol using permanganate–CdS quantum dot chemiluminescence system

A novel and highly sensitive chemiluminescence (CL) method for the determination of ethanol was developed based on the CdS quantum dots (QDs)–permanganate system. It was found that KMnO₄ could directly oxidize CdS QDs in acidic media resulting in relatively high CL emission. A possible mechanism was proposed for this reaction based on UV/Vis absorption, fluorescence and the generated CL emission spectra. However, it was observed that ethanol had a remarkable inhibition effect on this system. This effect was exploited in the determination of ethanol within the concentration range 12–300 µg/L, with detection at 4.3 µg/L. In order to evaluate the capability of presented method, it was satisfactorily utilized in the determination of alcohol in real samples. Copyright © 2014 John Wiley & Sons, Ltd.     

Contribution of LSP Effect to Light Absorption in Thin-Film Crystalline Silicon Solar Cells

Introducing periodic Ag gratings in the rear side of thin-film silicon excites localized surface plasmon (LSP) and Fabry-Perot (FP) effect. These two effects as well as an intrinsic one pass through absorption overlay together and all contribute to the light absorption in silicon. On the basis of electromagnetic field’s linear superposition, the absorptivity caused by LSP effect is separated from the overall absorptivity of a 500-nm-thick silicon and quantized by short current density. Finite difference time domain (FDTD) calculations were performed to obtain the absorptivity of silicon with different Ag grating parameters. The contribution of LSP effect to the light absorption is evaluated by photocurrent ratio and investigated under different Ag grating parameters. It is found that, as LSP effect is excited most intensively, the light absorption of silicon will also be enhanced extremely. By careful design, the overall short current density of silicon is optimized up to 25.4 mA/cm², where the contribution of LSP effect accounts for 38.6 %. Comparing to 14.5 mA/cm² for a reference silicon stack, it increases up to almost 75 %. These results may give design suggestions in implementation of plasmonic solar cell as high efficiency devices.     

湿氧化爆破稻秆的同步糖化发酵条件研究

探讨了木质纤维素经过湿氧化爆破后在同步糖化发酵过程中酵母产乙醇的基本规律.采用单因素方法对湿氧化爆破条件、酶系组成和添加量以及预酶解时间和温度进行了优化.不同湿氧化爆破预处理条件下的稻秆对同步糖化发酵工艺的影响较大,在预处理温度160 ℃,进氧压力为4×105 Pa,碱用量为6%(w/w),反应时间为20 min的条件...     

Potential inhibitors from wet oxidation of wheat straw and their effect on ethanol production of Saccharomyces cerevisiae: wet oxidation and fermentation by yeast

Alkaline wet oxidation (WO) (using water, 6.5 g/L sodium carbonate and 12 bar oxygen at 195 degrees C) was used as pretreatment method for wheat straw (60 g/L), resulting in a hydrolysate and a cellulosic solid fraction. The hydrolysate consisted of soluble hemicellulose (8 g/L), low-molecular-weight carboxylic acids (3.9 g/L), phenols (0.27 g/L = 1.7 mM) and 2-furoic acid (0.007 g/L). The wet oxidized wheat straw hydrolysate caused no inhibition of ethanol production by Saccharomyces cerevisiae ATCC 96581. Nine phenols and 2-furoic acid, identified to be present in the hydrolysate, were each tested in concentrations of 50-100 times the concentration found in the hydrolysate for their effect on fermentation by yeast. At these high concentrations (10 mM), 4-hydroxybenzaldehyde, vanillin, 4-hydroxyacetophenone and acetovanillone caused a 53-67% decrease in the volumetric ethanol productivity in S. cerevisiae compared to controls with an ethanol productivity of 3.8 g/L. The phenol acids (4-hydroxy, vanillic and syringic acid), 2-furoic acid, syringaldehyde and acetosyringone were less inhibitory, causing a 5-16% decrease in ethanol productivity. By adding the same aromatic compounds to hydrolysate (10 mM), it was shown that syringaldehyde and acetovanillone interacted negatively with hydrolysate components on the ethanol productivity. Fermentation in WO hydrolysate, that had been concentrated 6 times by freeze-drying, lasted 4 hours longer than in regular hydrolysate; however, the ethanol yield was the same. The longer fermentation time could not be explained by an inhibitory action of phenols alone, but was more likely caused by inhibitory interactions of phenols with carboxylic acids, such as acetic and formic acid.     

Effects of semi-starvation on the total body composition and absorptive function of the small intestine of the young adult female rat.

Sixteen female rats aged about 80 days and with a mean body weight of 175 g were fed 40% of their ad libitum intake of a laboratory chow. They were killed and analysed for water, protein, lipid and ash after 9, 21-5, 30-2 and 38-8% of body weight had been lost. Compared to a control group of four animals, the 38-8% group lost 13 g or 34% of their protein. The animals in the 21-5, 30-2 and 38-8% groups lost 7-5 g or 87% of their lipid leaving only 1-1 g of lipid. The percentage protein in the body was little affected by body weight loss but lipid decreased from 5 to 1%. In another experiment with 26 rats of 205 g mean body weight and aged about 115 days, absorption rates by the small intestine were measured in vivo after variable weight losses between 0 and 39%. D(+)-Glucose uptake was increased by about 70% in those animals which had lost only 5% of body weight and this increased uptake was retained in those rats which had lost up to 39% of body weight. The absorption of L-leucine was not affected by the decline in body weight compared to the controls but relative to body weight, the ability of the intestine to absorb increased. In the same animals, the wet and dry weights of the small intestine declined slightly faster than body weight and the length of the small intestine tended to decrease slightly with increasing loss of body weight.