生物炼制过程中木质素高值转化研究进展

木质素高值转化对于提升生物炼制经济性,促进社会经济绿色发展具有重要意义。然而,木质素结构复杂且不均一,其高值化利用仍存在技术壁垒,使得木质素应用尚未形成规模。文中首先综述了当前生物炼制过程中木质素高值转化面临的主要挑战。然后通过比较不同预处理技术对木质素分离、性质及其利用的主要影响,详细阐述了基于生物炼制理念发展的新型组合预处理技术。其次,针对木质素本征结构特性导致其利用效率低等问题,进一步详述了溶剂分级、膜分级、梯度沉淀分级等分级利用策略对克服木质素不均一性,改善其可加工性能的重要影响。再次,针对木质素利用策略,系统比较了木质素热化学转化和生物转化,结合生物质预处理及木质素分级,阐述了以生物炼制理念进行木质素高值转化的新策略。最后,总结了木质素利用过程中存在的挑战性问题,展望了木质素高效分离、分级及转化过程发展的新策略和新趋势。     

还田秸秆碳在土壤中的转化分配及对土壤有机碳库影响的研究进展

农田土壤有机碳库是全球碳循环的重要组成部分.随着秸秆还田技术的广泛应用,作物秸秆成为土壤外源碳的主要来源.秸秆碳在土壤中的转化与分配直接影响土壤有机碳组成与含量,进而改变土壤养分循环.基于近年来的相关研究,本文探讨了还田秸秆碳转化与分配过程的影响因子,详细介绍了参与秸秆碳同化过程的土壤微生物组成,归纳与阐述了秸秆碳对土壤有机碳组成、含量及其周转的影响.同时,就非生物因子对秸秆碳的生物转化效应的影响、秸秆碳转化过程中的生物和非生物因子的互作、秸秆碳氮和土壤碳氮循环的耦合作用、秸秆碳向土壤活性有机碳库或稳定性有机碳库转化的有效调控技术等主要研究方向进行了展望,以期为准确揭示秸秆还田条件下各类土壤有机碳的变化特征,进而为实现秸秆还田的高效培肥与固碳效应提供理论依据和技术支撑.     

秸秆覆盖免耕对土壤氮素转化细菌区系的影响

不同耕作方法影响土壤N素转化细菌的组成和数量.多年连续秸秆覆盖免耕试验结果表明,好氧固氮菌和厌氧固氮菌数量在铁茬处理土壤中较少,而在免耕与翻耕土壤中较多,免耕厌氧固氮菌数量明显地高于翻耕和铁茬,而铁茬最低,这种趋势特别在0～0.1m和0.1～0.2m土层中表现明显.土壤反硝化细菌的数量在表层土壤中较少,三种耕作方法相差较小,但在0.1～0.2m,0.2～0.3m土层中,翻耕反硝化细菌数量比免耕和铁茬多,而铁茬最少.不同耕作方法间氨氧化细菌数量相差不明显,免耕土壤中氨氧化细菌数量较高,动态变化趋势不规则.0～0.1m土层中免耕亚硝酸氧化细菌数量高于翻耕和铁茬,0.1～0.2m土层免耕与翻耕亚硝酸氧化菌数较多,而铁茬较少.     

有机硅化合物的生物合成与转化研究进展

非天然有机硅化合物不但在有机合成及功能材料的制备中发挥重要的作用,且在药物设计和改造中具有广阔的应用前景。近年来,酶催化有机硅化合物的生物合成研究取得了长足的进展。     

转化生长因子β受体的研究进展

转化生长因子β受体为胞膜蛋白,存在5种形态,Ⅲ型受体主要是调节受体与配体之间的亲和力及Ⅱ型受体的膜上表达.功能性受体则主要为Ⅰ、Ⅱ型.Ⅰ、Ⅱ型受体在介导信号传递时相互配合,又存在分工不同：Ⅰ型受体为介导转化生长因子β促细胞外基质合成的信号通道.而Ⅱ型受体则与细胞的增殖、分化密切相关.     

平菇类食用菌对农作物秸秆生物降解转化饲料的研究进展

综述了近年来国内外利用平菇类食用菌降解农作物秸秆的有关研究进展情况,主要包括限制秸秆饲料化的主要因素及提高秸秆饲料利用率的途径,平菇类食用菌降解秸秆的优势及其降解秸秆转化饲料的效果。并就笔者课题组近年来的研究总结了利用平菇类食用菌降解农作物秸秆的制约因素,以加快其应用于实际生产中。     

秸秆生物炭对两种典型土壤的养分特性及硅的化学形态的影响

研究选择华南地区两种典型土壤(水稻土和赤红壤),通过土壤培养试验,研究施用不同剂量(0%, 1%, 2%, 4%水稻秸秆生物炭处理对土壤养分及不同化学形态的硅含量随时间变化的动态影响。结果表明,不同剂量生物炭均能显著增加水稻土和赤红壤的pH值、总碳和速效钾含量,且随添加量的增加而增加。生物炭处理增加水稻土的碱解氮含量,但却降低赤红壤而的碱解氮含量。不同剂量生物炭添加均能显著提高两种土壤硅的不同化学形态的含量,其中4%的生物炭添加量效果最为明显。与对照相比, 4%的生物炭处理在培养第10 d时水稻土的CaCl₂-Si、Acetic-Si、H₂O₂-Si、Oxalate-Si、Na₂CO₃-Si含量分别增加300.3%、419.4%、91.9%、115.0%和82.5%,赤红壤则分别增加864.9%、1463.4%、646.4%、186.5%、80.2%。综上,秸秆生物炭对土壤养分及不同硅形态的影响与生物炭添加量以及土壤种类有关,赤红壤影响效果要优于水稻土。     

植物钾吸收基因及其遗传转化的研究进展

综述了近年来已分离和克隆的与植物钾离子吸收有关的基因及其在遗传转化方面的研究进展,对应用生物工程技术改良植物的钾营养性状进行了讨论。     

秸秆还田量对培肥农田黑土氮素初级转化速率的影响

秸秆还田是土壤培肥的重要措施之一,但培肥后土壤对氮素循环的调控功能是否具有可持续性以及与后续秸秆还田数量的关系尚不清楚。本研究对黑土旱地农田进行9年培肥处理后,设置了连续3年秸秆还田处理,秸秆还田量分别为年均秸秆产量(7500 kg·hm^-2)的100%、67%、33%和0,探讨不同秸秆还田量对培肥土壤(0～10 cm)氮素转化过程的影响。结果表明: 秸秆还田通过影响氮素初级转化速率,控制培肥土壤NH₄⁺-N和NO₃^--N的产生与消耗过程。当秸秆还田量低于67%时,NH₄⁺-N生成速率显著降低,而其消耗速率显著提高,土壤保留NH₄⁺-N的能力下降,而NO₃^--N生成速率增加,土壤NO₃^--N固持能力下降,增加NO₃^--N的积累及淋溶损失风险。对于东北旱地农田,利用秸秆归还进行黑土培肥,需要不低于67%收获量的秸秆持续还田才能维持土壤对氮素的保持功能。     

不同供氮水平对施用玉米秸秆后黑土氨基糖转化的影响

采用室内恒温(25 ℃)培养方法,设置4个氮素添加水平(0、60.3、167.2、701.9 mg N·kg^-1,依次标记为N₀、N_low、N_mid、N_hig),培养38周,研究不同无机氮素添加水平对施入玉米秸秆黑土的氨基糖转化的影响.结果表明：与对照样品相比,添加秸秆可显著促进氨基糖的微生物合成与积累,且在培养前期氨基糖的总量随着无机氮素添加水平的增加而增加,N_mid和N_hig处理氨基糖积累量显著高于N_low和N₀处理;随着培养时间的延长氨基糖总量有所下降,N_low和N₀处理的下降幅度高于N_mid和N_hig处理.不同无机氮素供应水平对各氨基单糖的影响也有所不同,以胞壁酸为代表的细菌细胞壁物质比真菌细胞壁残留物如氨基葡萄糖更易受到土壤碳氮供给的影响,但真菌细胞壁物质对土壤有机质的截获和稳定作用大于细菌.说明对于C/N较大的玉米秸秆,土壤中无机氮素的供给对氨基糖在土壤中的积累转化有明显影响,氮素缺乏会抑制微生物生长,使氨基糖的合成作用减弱,在微生物体中截获的氮源减少,不利于土壤氮素的积累.     

Fast Pyrolysis of Biomass Residues in a Twin-screw Mixing Reactor

Fast pyrolysis is being increasingly applied in commercial plants worldwide. They run exclusively on woody biomass, which has favorable properties for conversion with fast pyrolysis. In order to increase the synergies of food production and the energetic and/or material use of biomass, it is desirable to utilize residues from agricultural production, e.g., straw. The presented method is suitable for converting such a material on an industrial scale. The main features are presented and an example of mass balances from the conversion of several biomass residues is given. After conversion, fractionated condensation is applied in order to retrieve two condensates — an organic-rich and an aqueous-rich one. This design prevents the production of fast pyrolysis bio-oil that exhibits phase separation. A two phase bio-oil is to be expected because of the typically high ash content of straw biomass, which promotes the production of water of reaction during conversion.Both fractionated condensation and the use of biomass with high ash content demand a careful approach for establishing balances. Not all kind of balances are both meaningful and comparable to other results from the literature. Different balancing methods are presented, and the information that can be derived from them is discussed.     

Studies on biological decomposition of wheat straw

Summary The incorporation of undecomposed wheat straw in the soil along-with the micro-organisms favourably increased the yield of groundnut crop. An increase of 37 per cent in yield was recorded when wheat straw was inoculated withPenicillium digitatum and the C:P ratio was adjusted to 65. Inoculated treatments of narrower C:P ratio gave a higher yield than wider C:P ratio treatments inoculated with the same cultures. An increase in nitrogen uptake by groundnut plants was recorded due to incorporation of straw alongwith the micro-organisms in soil. The organic carbon and nitrogen content of the soil increased with all the treatments except control. The highest increase in organic carbon and nitrogen of the soil was observed with a treatment of wheat straw of 65 C:P ratio inoculated withS. coccosporum. The yield of wheat crop after groundnut was significantly more with several treatments than control plots. The highest increase of 79 per cent in grain yield of wheat was observed in the plots previouslq received with wheat straw of 200 C:P ratio.This paper is based on the data presented at IV Southern Regional Conference on Microbial Inoculants, held at Parbhani during 3–4 July 1978.     

Effect of dilute acid pretreatment on the saccharification and fermentation of rye straw

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.     

Molecular properties of a bent-core nematic liquid crystal A131 by multi-level theory simulations

ABSTRACT

Multi-level theory simulations have been performed to model a number of important molecular properties of a bent-core nematic liquid crystal (LC) A131. These important properties include molecular conformations, molecular Raman spectra, differential polarisability ratios, molecular crystals packing, atomic LC structures, order parameters, and Raman depolarisation spectra. The simulations contain four theory levels, involving molecular quantum chemistry, molecular crystal packing, super cell density functional based tight binding optimisation, and super cell molecular dynamics calculations. To heat initial optimised super cell structures, molecular dynamics simulations reveal phase transitions to uniaxial and biaxial nematic phases from molecular crystals. LC atomic structures result in direct calculations on order parameters, which can be further applied to computations on Raman depolarisation spectra with differential polarisability ratios, obtained in the molecular quantum chemistry theory level. The good agreement of simulated Raman depolarisation spectra with the experiment provides a detailed analysis on the unusually low values of experimental uniaxial order parameters.     

戊糖和己糖共发酵生产燃料乙醇条件研究

利用嗜鞣管囊酵母P-01对木糖和葡萄糖共发酵生产燃料乙醇的条件进行了试验研究,结果表明,木糖和葡萄糖混合液生产燃料乙醇的最佳条件为发酵液的pH值5.5、30℃、摇床转速120 r/min、接种量10%、发酵液初始糖浓度6%、葡萄糖与木糖之比为2、发酵周期为84h。在最佳发酵条件下,发酵醪液中的燃料乙醇浓度为2.101%,糖醇转化率为35%。     

碳中和视角下秸秆处置方式对碳源汇的贡献

探明农作物秸秆在不同处置方式下的碳源汇时空变化特征,对优化我国秸秆资源利用政策、实现碳减排最大化、实现碳中和目标具有重要意义。本研究以国家统计年鉴数据为基础,对我国31个省农作物秸秆不同处置下的碳排放、碳减排、碳增汇及其价值量的变化趋势进行研究。结果表明: 2008—2019年间,我国秸秆焚烧年均碳排放量为874万t CO₂e,2014年以来碳排放年均减少率为17.3%;能源化利用年均碳减排量为3982万t CO₂e,其中,秸秆生产固体成型燃料碳减排贡献最大,约占能源化碳减排总量的98%;秸秆还田碳汇量总体呈逐年上升趋势,年均碳汇量为2.71亿t CO₂e;我国秸秆处置存在碳生态盈余,净碳减排量年均增长率为9.8%,净碳减排强度及其价值量均呈增长趋势,2019年分别高达2.62 t·hm^-2和76.19元·hm^-2。我国秸秆年均碳排放、能源碳减排、秸秆还田碳汇以及净碳减排大致呈“东高西低”的空间分布规律,且地区差异及空间聚集性是三者的最主要外部特征。     

Potential use of bamboo resources in energy value-added conversion technology and energy systems

Bamboo has been identified as a promising solution to the energy crisis and climate change as a source of biomass energy. Due to its rapid growth and high-value products, bamboo is considered as a potential source of biomass energy. Bamboo contains a significant amount of cellulose and hemicellulose, which can be converted to sugar constituents, making it an ideal raw material for energy production. This article reviews the different processes of producing bioethanol, biogas, biochar, and bio-oil from bamboo biomass using techniques such as pyrolysis, hydrothermal liquefaction, fermentation, and anaerobic digestion, and discusses the opportunities and challenges of these conversion technologies. It also reviews the main types and morphological characteristics of energy bamboo species and proposes an evaluation system for energy bamboo species, which optimizes the utilization efficiency of bamboo biomass energy and maximizes benefits by adopting appropriate methods for producing bioenergy based on the characteristics of different bamboo species.     

Biological conversion of gaseous alkenes to liquid chemicals

Industrial gas-to-liquid (GTL) technologies are well developed. They generally employ syngas, require complex infrastructure, and need high capital investment to be economically viable. Alternatively, biological conversion has the potential to be more efficient, and easily deployed to remote areas on relatively small scales for the utilization of otherwise stranded resources. The present study demonstrates a novel biological GTL process in which engineered Escherichia coli converts C2–C4 gaseous alkenes into liquid diols. Diols are versatile industrially important chemicals, used routinely as antifreeze agents, polymer precursors amongst many other applications. Heterologous co-expression of a monooxygenase and an epoxide hydrolase in E. coli allows whole cell conversion of C2–C4 alkenes for the formation of ethylene glycol, 1,2-propanediol, 1,2-butanediol, and 2,3-butanediol at ambient temperature and pressure in one pot. Increasing intracellular NADH supply via addition of formate and a formate dehydrogenase increases ethylene glycol production titers, resulting in an improved productivity of 9 mg/L/h and a final titer of 250 mg/L. This represents a novel biological method for GTL conversion of alkenes to industrially valuable diols.     

The economics of producing sustainable aviation fuel: a regional case study in Queensland,Australia

The airline industry has a strong interest in developing sustainable aviation fuels, in order to reduce their exposure to increasing oil prices and cost liability for greenhouse gas emissions. The feasibility and cost of producing sustainable biomass‐based jet fuels at a sufficient scale to materially address these issues is an enormous challenge. This paper builds directly on the biophysical study by H.T. Murphy, D.A. O'Connell, R.J. Raison, A.C. Warden, T.H. Booth, A. Herr, A.L. Braid, D.F. Crawford, J.A. Hayward, T. Javonovic, J.G. McIvor, M.H. O'Connor, M.L. Poole, D. Prestwidge, N. Raisbeck‐Brown & L. Rye, In review, which examined a 25 year scale‐up strategy to produce 5% of projected jet fuel demand in Australia in 2020 (470 mL) in the Fitzroy region of Queensland, Australia. The strategy was based on the use of a mixed ligno‐cellulosic biomass feedstock and assumed, for the sake of exploring and quantifying the scenario, a simplified two‐step conversion process – conversion of biomass to crude bio‐oil within the region, and upgrade to jet fuel at a central Brisbane facility. This paper provides details on the costs of production in this scenario, focusing on two different strategies for biomass utilization, and two types of novel small–medium scale conversion technologies. The cost analyses have taken into account technology learning curves, different economies of scale and key cost sensitivities. The cost of biomass‐based jet fuels is estimated to be between 0.70 and 1.90 The airline industry has a strong interest in developing sustainable aviation fuels, in order to reduce their exposure to increasing oil prices and cost liability for greenhouse gas emissions. The feasibility and cost of producing sustainable biomass‐based jet fuels at a sufficient scale to materially address these issues is an enormous challenge. This paper builds directly on the biophysical study by H.T. Murphy, D.A. O'Connell, R.J. Raison, A.C. Warden, T.H. Booth, A. Herr, A.L. Braid, D.F. Crawford, J.A. Hayward, T. Javonovic, J.G. McIvor, M.H. O'Connor, M.L. Poole, D. Prestwidge, N. Raisbeck‐Brown & L. Rye, In review, which examined a 25 year scale‐up strategy to produce 5% of projected jet fuel demand in Australia in 2020 (470 mL) in the Fitzroy region of Queensland, Australia. The strategy was based on the use of a mixed ligno‐cellulosic biomass feedstock and assumed, for the sake of exploring and quantifying the scenario, a simplified two‐step conversion process – conversion of biomass to crude bio‐oil within the region, and upgrade to jet fuel at a central Brisbane facility. This paper provides details on the costs of production in this scenario, focusing on two different strategies for biomass utilization, and two types of novel small–medium scale conversion technologies. The cost analyses have taken into account technology learning curves, different economies of scale and key cost sensitivities. The cost of biomass‐based jet fuels is estimated to be between 0.70 and 1.90 $ L^?1 when the efficiency of conversion of biomass to biocrude and subsequently to aviation fuel is varied by ±10% of published values, with an average value of 1.10 $ L^?1. This is within the range of the projected 2035 conventional jet fuel price of 1.50 $ L^?1. Therefore, biomass‐based jet fuel has the potential to contribute to supply of Australia's jet fuel needs in the future.     

Assessment of leaf/stem ratio in wheat straw feedstock and impact on enzymatic conversion

The composition of wheat straw leaf and stem fractions were characterized using traditional strong acid hydrolysis, and monoclonal antibodies using comprehensive microarray polymer profiling (CoMPP). These results are then related to high throughput lignocellulose pretreatment and saccharification screening data. Pure leaf fraction of wheat straw was the least recalcitrant compared to pure stem and easily digested by commercial cellulases after moderate hydrothermal pretreatment; 63% and 31% (w/w) of glucan, 88% and 61% of xylan were released from the leaf and stem fractions, respectively. By preparing samples of various leaf‐to‐stem (L/S) ratios, we found shifting conversion behavior as processing parameters were modified. Increasing the enzyme dosage, pretreatment temperature and pretreatment time all significantly improved conversion rates in samples with more than 50% leaf content, whereas less impact was observed on samples with less than 50% leaf content. Enzyme affinity, desorption and readsorption with leaf and stem fractions may affect the sugar yield in wheat straw saccharification. The data suggest that the L/S ratio is an important parameter when adjusting or optimizing conversion processes and additionally in feedstock breeding. Furthermore, this highlights the need for rapid techniques for determining L/S ratio in wheat straw harvests. The CoMPP data on specific carbohydrates and leaf pectin highlight carbohydrate epitopes that may be useful as markers in the development of novel screening techniques; especially pectin or arabinogalactan proteins related epitopes are promising.