A combined acidification/PEO flocculation process to improve the lignin removal from the pre-hydrolysis liquor of kraft-based dissolving pulp production process

The presence of lignin impairs the utilization of the hemicelluloses dissolved in the pre-hydrolysis liquor (PHL) of the kraft-based dissolving pulp production process. In this paper, a novel process was developed by combining the acidification and poly ethylene oxide (PEO) flocculation concepts to improve the lignin removal. The results showed that the lignin removal was improved by the addition of PEO to the acidified PHL, particularly at a low pH of 1.5. The main mechanisms involved are the lignin/PEO complex formation and the bridging of the formed complexes. This hypothesis was supported by the turbidity, FTIR and particle size measurements. Interestingly, the hemicelluloses removal from the acidification/PEO flocculation was marginal, which would be beneficial for the down-stream ethanol production from the PHL. Additionally, a process flow diagram was proposed that incorporates this new concept into the existing configuration of kraft-based dissolving pulp production process.     

Recovery of lignocelluloses from pre-hydrolysis liquor in the lime kiln of kraft-based dissolving pulp production process by adsorption to lime mud

Dissolved lignocelluloses from the pre-hydrolysis liquor (PHL) of kraft-based dissolving pulp production process were recovered by adsorption to lime mud produced in the causticizing plant of the kraft process. The adsorption of lignocelluloses was a fast process, and could be completed within one hour. The addition of polydiallyldimethylammonium chloride (PDADMAC) significantly increased the amounts of adsorbed lignin and hemicelluloses, which more than doubled at the PDADMAC dosage of 0.1% (based on the weight of PHL). The measured heating values of the adsorbed lignocelluloses indicate that adsorption of lignocelluloses to lime mud may result in the energy saving of the lime kiln. The process proposed in this study could also be adapted to decrease inhibitor concentrations (lignin and acetic acid) if the dissolved hemicelluloses in the PHL were used to produce value-added products, e.g., ethanol, xylitol, based on the fermentation process.     

Extracting value from Eucalyptus wood before kraft pulping: effects of hemicelluloses solubilization on pulp properties

Eucalyptus globulus wood samples were subjected to autohydrolysis for extracting hemicelluloses, and the resulting solids were assayed as substrates for kraft pulping and further Totally Chlorine Free (TCF) bleaching. The susceptibility of treated solids to kraft processing was assessed under selected experiments covering the optimum experimental range. In order to establish a basis for comparison, samples of untreated wood were also subjected to kraft delignification. The best kraft pulps obtained from autohydrolyzed solids were subjected to an optimized TCF bleaching sequence involving double alkaline oxygen and pressurized H₂O₂ processing, and characterized using standard methods. The suitability of the final product obtained by autohydrolysis-kraft delignification-TCF bleaching for specific purposes is discussed on the basis of the experimental results.     

An integrated process for removing the inhibitors of the prehydrolysis liquor of kraft-based dissolving pulp process via cationic polymer treatment

The prehydrolysis liquor (PHL) of the kraft‐based dissolving pulp production process contains various amounts of hemicelluloses that can be utilized in the production of value‐added products. In this work, a new process was proposed for removing the inhibitors of PHL via employing a flocculation concept to facilitate the utilization of hemicelluloses. Lignin, lignocelluloses/cationic polymer complexes, and possibly ethanol are the main products of this process. This process has been experimentally evaluated with an industrially produced PHL and cationic polymers. The results showed that 16% of lignin, 19% of acetic acid, 43% of furfural, and insignificant amount of sugars were removed from PHL via pretreating PHL with acid and lime at pH 7. Furthermore, by adding 0.4–0.5 mg g^?1 polydiallyldimethylammonium chloride (PDADMAC) or chitosan to the pretreated PHL, 12–14% acetic acid, 40–50% furfural, 5–6% monomeric sugars, and 25% oligomeric sugars were removed from the PHL. The complexes made from these components may be applied as organic fillers in various industries. Alternatively, by adding 1.2 or 1.4 mg g^?1 PDADMAC or chitosan to the pretreated PHL, 30 or 35% of lignin was removed, respectively, which induced complexes that could be used as a fuel source. The composition of the complexes formed was also determined in this work. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 998–1004, 2012     

Bio-refinery system of DME or CH4 production from black liquor gasification in pulp mills

There is great interest in developing black liquor gasification technology over recent years for efficient recovery of bio-based residues in chemical pulp mills. Two potential technologies of producing dimethyl ether (DME) and methane (CH₄) as alternative fuels from black liquor gasification integrated with the pulp mill have been studied and compared in this paper. System performance is evaluated based on: (i) comparison with the reference pulp mill, (ii) fuel to product efficiency (FTPE) and (iii) biofuel production potential (BPP). The comparison with the reference mill shows that black liquor to biofuel route will add a highly significant new revenue stream to the pulp industry. The results indicate a large potential of DME and CH₄ production globally in terms of black liquor availability. BPP and FTPE of CH₄ production is higher than DME due to more optimized integration with the pulping process and elimination of evaporation unit in the pulp mill.     

Identification of white-rot and soft-rot fungi increasing ethanol production from spent sulfite liquor in co-culture with Saccharomyces cerevisiae

Aim:  To identify fungi that are capable of increasing ethanol production from lignocellulose in spent sulfite liquor.
Methods and Results:  In a batch fermentation study, the fungal mix could produce 24·61 g l⁻¹ ethanol using spent sulfite liquor as substrate. The fungal mix grew well on glucose, xylose, hemicellulose and cellulose. In addition, we were able to identify the fungal mix by use of PCR-amplification of DNA and sequencing, and they were identified as Chalara parvispora and Trametes hirsuta/T. versicolor. In a reconstitution study, the identified fungi were shown to produce equal amount of ethanol as the fungal mix. We were also able to show that C. parvispora could produce ethanol from xylose.
Conclusion:  The present study has shown that ethanol production from biomass can be increased by use of C. parvispora and T. versicolor when compared with fermentation using only S. cerevisiae .
Significance and Impact of the Study:  The study shows that refining biomass by ethanol production from spent sulfite liquor, a lignocellulose material, can be increased by adding C. parvispora and T. versicolor , and it is thus of great potential economical impact.     

Mesophilic batch anaerobic co-digestion of pulp and paper sludge and monosodium glutamate waste liquor for methane production in a bench-scale digester

This paper presented results from anaerobic co-digestion of pulp and paper sludge (PPS) and monosodium glutamate waste liquor (MGWL). A bench-scale anaerobic digester, 10 L in volume was developed, to operate under mesophilic (37 ± 2 °C) batch condition. Under versatile and reliable anaerobic conduct, high efficiency for bioconversion of PPS and MGWL were obtained in the system. The accumulative methane yield attained to 200 mL g⁻¹ VS_added and the peak value of methane daily production was 0.5 m³/(m³ d). No inhibitions of volatile fatty acids (VFAs) and ammonia on anaerobic co-digestion were found. pH 6.0-8.0 and alkalinity 1000-4000 mg CaCO₃/L were got without adjustment. This work showed that there was a good potential to the use of PPS and MGWL to anaerobic co-digestion for methane production.     

舍得老酒对大鼠肠屏障功能及肠道菌群的影响

探究舍得老酒对大鼠肠屏障功能及其肠道菌群构成的影响。

将28只SPF级180～220 g SD雄性大鼠随机分为4组（n = 7）：对照组、乙醇组、舍得老酒1组及舍得老酒2组。分别灌胃生理盐水、酒精（7.6 mL/kg）及舍得老酒（3.8 mL/kg和7.6 mL/kg 2个剂量）,连续灌胃4周。检测结肠紧密连接蛋白mRNA表达水平,血清炎症相关分子水平;采用流式细胞仪检测脾脏免疫细胞水平;采用测序检测粪便肠道菌群构成。

乙醇组大鼠紧密连接蛋白mRNA表达水平较低,血清中的肿瘤坏死因子-α浓度较高,白介素10浓度较低,而舍得老酒2个剂量组均不同程度地改善了乙醇对大鼠肠屏障功能的不良反应。舍得老酒7.6 mL/kg剂量组可能通过降低CD4⁺ T细胞比例而减少炎症的发生。舍得老酒3.8 mL/kg组大鼠肠道菌群alpha多样性高于其他3组。4组大鼠肠道菌群组成具有一定差异,门水平上,乙醇组拟杆菌门相对丰度较其他组高,厚壁菌门与拟杆菌门比值（F/B）低于其他3组;属水平上,乙醇组Ruminiclostridium_6、Prevotella_9及Lachnospiraceae_NK4A136_group丰度较对照组增加,舍得老酒3.8 mL/kg组的接近对照组,乙醇组Lactobacillus丰度降低,舍得老酒3.8 mL/kg组Lactobacillus丰度增加。

低剂量组舍得老酒可改善大鼠肠屏障功能,并可通过增加肠道菌群丰度及多样性、抑制部分肠道致病菌的生长及增加有益菌,从而起到一定的调节肠道菌群的作用。

     

重组4-甲基苯酚消减乳酸菌的构建及其在白酒酿造体系中的功能

【背景】4-甲基苯酚是众多发酵食品中的异嗅味物质,阈值较低,如白酒中百万分之一的4-甲基苯酚即可对白酒风味造成不利影响。【目的】构建能消减4-甲基苯酚的乳酸菌菌株,探索其在白酒酿造中的应用潜力。【方法】将来源于谷氨酸棒杆菌的4-甲基苯基磷酸酯合成酶编码基因creI与creH在短乳杆菌中表达,探究过表达菌株对白酒酿造体系中4-甲基苯酚的消减能力。【结果】creIH过表达菌株在液体培养基中可有效消减4-甲基苯酚,消减能力达2 130μg/L;在模拟白酒固态酿造体系中,creIH过表达菌株消减4-甲基苯酚的能力达530μg/kg,消减率为37.9%。【结论】首次构建了4-甲基苯酚的消减乳酸菌菌株,为白酒酿造体系中4-甲基苯酚的消减提供了新的策略。     

Microorganisms in Daqu: a starter culture of Chinese Maotai-flavor liquor

Maotai-flavor liquor, a famous traditional Chinese drink, is distilled from fermented sorghum in the southern province of China. Moreover, it is of interest as one of the few examples of liquor distilled from the product of a fermentation using a wild microflora starter. Daqu is the starter of this fermentation process. Daqu is a mixture of two components: milled wheat and a complex microbial community. The composition and the effects of this microbial group are largely unknown. In this study, we have analysed the constituents of the microbial community and the development of microorganisms in the industrial Daqu preparation and ripening process. More than 200 colonies were isolated and characterized. The isolates were discriminated by phenotypic and conventional biochemical taxonomic methods. The results revealed the presence of bacteria, moulds and yeasts. Bacteria consist of Bacillus, Acetobacter, Lactobacillus, and Clostridium, among which Bacillus strains were found to be predominant. Moulds consisted of Aspergillus, Mucor, Rhizopus, Monascus and Trichoderma, and Aspergillus strains were found to be predominant in the six different biotypes. Yeasts comprised Saccharomyces, Hansenula, Candida, Pichia, and Torulaspora. The most frequently isolated yeasts belonged to the genus Saccharomyces. The microbial diversity shift showed that the microbial genera changed with increasing ripening time. Knowledge of the microbial diversity in Daqu provides a basis for microflora management and understanding of the role of microbes in the Daqu production process, and the contribution of Daqu performed as a starter culture to Maotai-flavor liquor.     

清香型白酒固态酿造过程中酵母种群结构和多样性分析

【目的】探索清香型白酒固态酿造过程中酵母的种群结构和生态多样性变化规律,为科学认识白酒酿造的过程与机制提供理论依据。【方法】运用WL鉴别培养基和26S rRNA D1/D2序列分析方法对清香型白酒3种典型大曲和酒醅发酵过程的酵母进行分类学研究。【结果】从清香型白酒固态酿造过程中共鉴定出10种酵母,分别为Saccharomyces cerevisiae、Issatchenkia orientalis、Pichia anomala、Saccharomycopsis fibuligera、Pichia fermentans、Trichosporon asahii、Hanseniaspora osmophila、Pichia farinosa、Pichia membranifaciens和Clavispora lusitaniae。其中T.asahii、C.lusitaniae、H.osmophila、P.membranifaciens、P.farinose和P.fermentans为首次从清香型白酒酿造过程中分离获得的酵母种类。考察3种典型大曲(清茬、红心、后火曲)和大茬、二茬酒醅发酵过程的酵母种群结构变化规律显示,3种大曲具有相同的优势菌种S.fibuligera,但三者酵母结构组成差异较大,且清茬曲含有最多的酵母数量和种类。酒醅发酵过程中的酵母种群结构与3种大曲均明显不同,大茬和二茬酒醅酵母结构也不同,两种酒醅发酵后期的优势酵母均为S.cerevisiae,而发酵前期优势酵母则分别是H.osmophila和P.membranifaciens。【结论】深入研究了清香型白酒酿造过程中微生物的分布特征和规律,对认识清香型白酒酿造过程和群体微生物的发酵机制,以及丰富我国传统酿造食品微生物的研究,具有重要的理论和实践价值。     

浓香型白酒糟醅及窖泥产香功能菌的研究进展

浓香型白酒主要香气物为己酸乙酯、乳酸乙酯、乙酸乙酯和丁酸乙酯四大酯类,白酒微生物发酵过程中酯类合成主要是酸与醇在酯化酶的作用下产生,因此产香功能菌包括香气及其前体物产生菌和酯化酶产生菌.本文综述了浓香型白酒糟醅及窖泥主要产香功能菌的来源、组成、鉴定方法、功能特性、相互关系及其在浓香型白酒生产过程中的应用等方面的研究进展,旨为浓香型白酒重要微生物的研究提供思路,为其发酵过程控制提供理论依据.     

Prevention mechanisms of glucose intolerance and obesity by cacao liquor procyanidin extract in high-fat diet-fed C57BL/6 mice

In this study, we investigated whether cacao liquor procyanidin (CLPr) extract, which consists of 4.3% catechin, 6.1% epicatechin, 39.4% procyanidins and others, ameliorated hyperglycemia and obesity in C57BL/6 mice fed a control or high-fat diet for 13 weeks. CLPr suppressed high-fat diet-induced hyperglycemia, glucose intolerance and fat accumulation in white adipose tissue. CLPr also promoted translocation of glucose transporter 4 (GLUT4) and phosphorylation of AMP-activated protein kinase α (AMPKα) in the plasma membrane of skeletal muscle and brown adipose tissue. Phosphorylation of AMPKα was also enhanced in the liver and white adipose tissue. CLPr up-regulated the gene and protein expression levels of uncoupling protein (UCP)-1 in brown adipose tissue and UCP-3 in skeletal muscle. These results indicate that CLPr is a beneficial food material for the prevention of hyperglycemia and obesity. Activation of AMPKα, translocation of GLUT4 and up-regulation of UCP expression in skeletal muscle and adipose tissue are involved in the molecular mechanisms by which CLPr prevents hyperglycemia and obesity.     

Composition of <Emphasis Type="Italic">nifH</Emphasis> in a wastewater treatment system reliant on N<Subscript>2</Subscript> fixation

High levels of nitrogen fixation have been observed in the wastewaters of pulp and paper mills. In this study, we show that nitrogen fixation in a model pulp and paper wastewater treatment system is supported by a high density of nifH sequences that are of low diversity. Quantitative PCR revealed a ratio of nifH to 16S rDNA of 1.14 +/- 0.76 which shows that very high levels of the nifH gene were enriched to support the high rates of nitrogen fixation that occur in this wastewater. Changes in wastewater composition and dissolved oxygen levels did not affect the nifH levels and allowed stable wastewater treatment. The nifH sequences identified display a similar profile to those seen in forest soil environments where nifH sequences derived from alpha-proteobacteria and beta-proteobacteria are also prevalent.     

Mutants of the pentose‐fermenting yeast Pichia stipitis with improved tolerance to inhibitors in hardwood spent sulfite liquor

Mutants of Pichia stipitis NRRL Y‐7124 able to tolerate and produce ethanol from hardwood spent sulfite liquor (HW SSL) were obtained by UV mutagenesis. P. stipitis cells were subjected to three successive rounds of UV mutagenesis, each followed by screening first on HW SSL gradient plates and then in diluted liquid HW SSL. Six third generation mutants with greater tolerance to HW SSL as compared to the wild type (WT) were isolated. The WT strain could not grow in HW SSL unless it was diluted to 65% (v/v). In contrast, the third generation mutants were able to grow in HW SSL diluted to 75% (v/v). Mutants PS301 and PS302 survived even in 80% (v/v) HW SSL, although there was no increase in cell number. All the third generation mutants exhibited higher growth rates but significantly lower growth yields on xylose or glucose compared to the WT. The mutants fermented 4% (w/v) glucose as efficiently as the WT and fermented 4% (w/v) xylose more efficiently with a higher ethanol yield than the WT. In a medium containing 4% (w/v) each of xylose and glucose, all the third generation mutants utilized glucose as efficiently and xylose more efficiently than the WT. This resulted in higher ethanol yield by the mutants. The mutants retained the ability to utilize galactose and mannose and ferment them to ethanol. Arabinose was consumed slowly by both the mutants and WT with no ethanol production. In 60% (v/v) HW SSL, the mutants utilized and fermented glucose, mannose, galactose and xylose while the WT could not ferment any of these sugars. Biotechnol. Bioeng. 2009; 104: 892–900. © 2009 Wiley Periodicals, Inc.     

Effect of cultivation pH and agitation rate on growth and xylanase production by Aspergillus oryzae in spent sulphite liquor

The effects of cultivation pH and agitation rate on growth and extracellular xylanase production by Aspergillus oryzae NRRL 3485 were investigated in bioreactor cultures using spent sulphite liquor (SSL) and oats spelts xylan as respective carbon substrates. Xylanase production by this fungus was greatly affected by the culture pH, with pH 7.5 resulting in a high extracellular xylanase activity in the SSL-based medium as well as in a complex medium with xylan as carbon substrate. This effect, therefore, was not solely due to growth inhibition at the lower pH values by the acetic acid in the SSL. The xylanase activity in the SSL medium peaked at 199 U ml(-1) at pH 7.5 with a corresponding maximum specific growth rate of 0.39 h(-1). By contrast, the maximum extracellular beta-xylosidase activity pf 0.36 U ml(-1) was recorded at pH 4.0. Three low molecular weight xylanase isozymes were secreted at all pH values within the range of pH 4-8, whereas cellulase activity on both carbon substrates was negligible. Impeller tip velocities within the range of 1.56-3.12 m s(-1) had no marked effect, either on the xylanase activity, or on the maximum volumetric rate of xylanase production. These results also demonstrated that SSL constituted a suitable carbon feedstock as well as inducer for xylanase production in aerobic submerged culture by this strain of A. oryzae.     

Improved ethanol tolerance of Saccharomyces cerevisiae strains by increases in fatty acid unsaturation via metabolic engineering

To enhance the ethanol tolerance of Saccharomyces cerevisiae, the Arabidopsis thaliana FAD2 gene and/or the S. cerevisiae OLE1 gene were over-expressed in this yeast. The transformant over-expressing both these genes could not only synthesize dienoic fatty acids but also increased the unsaturated fatty acid content of membrane lipid and then showed the highest viability in the presence of 15% (v/v) ethanol.     

Application of acetate buffer in pH adjustment of sorghum mash and its influence on fuel ethanol fermentation

A 2 M sodium acetate buffer at pH 4.2 was tried to simplify the step of pH adjustment in a laboratory dry-grind procedure. Ethanol yields or conversion efficiencies of 18 sorghum hybrids improved significantly with 2.0–5.9% (3.9% on average) of relative increases when the method of pH adjustment changed from traditional HCl to the acetate buffer. Ethanol yields obtained using the two methods were highly correlated (R ² = 0.96, P < 0.0001), indicating that the acetate buffer did not influence resolution of the procedure to differentiate sorghum hybrids varying in fermentation quality. Acetate retarded the growth of Saccharomyces cerevisiae, but did not affect the overall fermentation rate. With 41–47 mM of undissociated acetic acid in mash of a sorghum hybrid at pH 4.7, rates of glucose consumption and ethanol production were inhibited during exponential phase but promoted during stationary phase. The maximum growth rate constants (μ _max) were 0.42 and 0.32 h⁻¹ for cells grown in mashes with pH adjusted by HCl and the acetate buffer, respectively. Viable cell counts of yeast in mashes with pH adjusted by the acetate buffer were 36% lower than those in mashes adjusted by HCl during stationary phase. Coupled to a 5.3% relative increase in ethanol, a 43.6% relative decrease in glycerol was observed, when the acetate buffer was substituted for HCl. Acetate helped to transfer glucose to ethanol more efficiently. The strain tested did not use acetic acid as carbon source. It was suggested that decreased levels of ATP under acetate stress stimulate glycolysis to ethanol formation, increasing its yield at the expense of biomass and glycerol production. Names are necessary to report factually on available data; however, the U.S. Department of Agriculture neither guarantees nor warrants the standard of the product, and use of the name by the U.S. Department of Agriculture implies no approval of the product to the exclusion of others that may also be suitable.     

Mitigation of Heavy Metal Contamination in Soil via Successive Pig Slurry Application

This study evaluates heavy metal removal associated with phytomass management in a Typic Hapludox after three applications of pig slurry. Like humic acids in pig slurry were characterized through physics and chemical spectroscopy technics. Heavy metal levels were determined in ration that was offered to pigs, anaerobically digested pig slurry, and plant tissues from pig slurry-fertilized black oat (Avena strigosa Schreb.) and ryegrass (Lolium multiflorum Lam.) intercrop. Soil contamination was evaluated by the pseudo-total heavy metal levels in six soil layers and the bioavailable levels in the top soil layer. Results indicate that the ration is the origin of heavy metals in the pig slurry. The approximate levels in the ration were as follows (mg kg^?1): Cu 23.9, Zn 92.02, 153.15, Mn 30.98, Ni 0.23, Pb 10.75, Cr 0.34, Co 0.08, and Cd 0.05. The approximate levels of these metals in the pig slurry were as follows (mg kg^?1): Cu 71.08, Zn 345.67, Fe 83.02, Mn 81.71, Ni 1.13, Pb 4.35, Co 0.28, and Cd 0.16. Like humic acids contained 55% aliphatic chains, 14% oxygenated aliphatic chains, and 15% carboxyls, demonstrating their high capacity for interaction with heavy metals by forming soluble complexes. Soil contamination was indicated by the accumulation of heavy metals in the six soil layers in relation to the applied pig slurry dose (ranged as follows (mg kg^?1): Cu 110 to 150, Zn 50 to 120, Ni 20 to 40, and Pb 12 to 16) and as bioavailable forms (levels ranged as follows (mg kg^?1): Cu < 1, Zn 1.0–1.5, Ni 0.1–1.5, and Pb 1.9–6.3). The positive correlation between heavy metal accumulation in the plants and soil bioavailable heavy metal levels and the lowest heavy metal levels under higher intensity of phytomass removal demonstrate the ability of phytomass management to reduce soil contamination.     

回交育种中供体基因组成分的分布及其应用

推导了回交群体中供体基因组成分的条件概率分布,并用平均数预测各个体的供体染色体片段的大小.预测的精确度则用有关方差的公式,以供体的实际片断大小(y)与根据标记基因型预测的供体片断大小(yp)的相关表示,并表达为标记密度的函数.结果表明虽然在标记密度中等(例如40cM/标记)时即能获得y和yp的高度相关,但对一个大群体,仍必须通过高密度的标记图(例如10～20cM/标记)才可能鉴别出其中的最佳个体.因此,为了在标记辅助回交育种中充分利用标记信息,应当分步骤鉴定标记基因型和选择个体.这就是先根据少数标记对所有个体作初步选择,再根据较多标记对少数个体作精细选择.这样,在基因渐渗实验中,就可以既提高对大群体的选择强度又只要鉴定有限数目的标记基因型.这是一种非常有效的方法.