利用树干毕赤酵母发酵玉米秸秆制备燃料酒精

采用湿热预处理(195℃,15min)与同步糖化发酵对玉米秸秆制备酒精进行了研究。结果表明:玉米秸秆经过湿热预处理后,86.5%纤维素保留在滤饼中,而大部分半纤维素被溶解。在底物质量体积含量50g/L,温度30℃,pH值5.5,摇床转速130r/min条件下,树干毕赤酵母(Pichia stipitis)利用预处理后的玉米秸秆经过192h同步糖化发酵,酒精浓度达到了12.12g/L,对应的酒精产量和生产效率分别为0.34g/g(葡萄糖+木糖)和0.065g/(L·h)。该项研究为工业化生产打下了基础。     

驯化树干毕赤酵母发酵产乙醇的研究

以玉米秸秆蒸汽爆破液为底物培养基,通过逐步提浓的方式对树干毕赤酵母菌株（Pichiastipitis）NLP23进行耐抑制物驯化,驯化后的菌株对汽爆液中甲酸和乙酸等抑制物的耐受能力可分别达到2．70g／L和3．54g／L,较出发菌株分别提高253．40％和277．80％。在含有57．34g/L木糖和13．84g／L葡萄糖的汽爆液中发酵42h,糖利用率和乙醇得率可达到97．89％和65．83％,乙醇质量浓度为21．56g/L,同时生成4．16g/l木糖醇。玉米秸秆蒸汽爆破液中含有多种抑制酵母生长和发酵的有毒物质,主要是甲酸、乙酸、乙酰丙酸、糠醛和羟甲基糠醛,其中甲酸和乙酸含量较高,是影响树干毕赤酵母NLP23发酵汽爆液的主要抑制物。     

Mathematical model for ethanol production from mixed sugars by Pichia stipitis

A mathematical model for estimating the dynamic behavior of ethanol production from mixed sugars such as glucose and xylose is presented. This model was constructed by introducing the term for ethanol production into the diauxic growth model proposed previously by the authors. It was assumed that the first substrate, glucose, is metabolized by a constitutive enzyme and the second substrate, xylose, is utilized by an inducible enzyme. The synthesis of the inducible enzyme is controlled by the catabolite repression caused by glucose and with the induction caused by xylose as an inducer, and the xylose is then converted into cell mass and ethanol by the inducible enzyme. The parameters of the model were estimated from the experimental data in the medium containing glucose and xylose, singly or in combination in a batch culture. The application of the model was examined for experiments in both batch and continuous culture, with glucose and xylose as carbon sources. The calculated values, according to the model, corresponded satisfactorily with experimental data, such as cell growth, substrate consumption, and ethanol production, especially in the estimation of the lag times between the first log phase and the second log phase in cell growth and ethanol production. © 2001 Society of Chemical Industry     

有机废弃物厌氧共发酵制氢研究进展

化石燃料的消耗和有机废弃物的大量排放带来了严重的环境问题,而利用有机废弃物进行厌氧发酵制氢是可持续且环境友好的。为了克服单一底物厌氧发酵制氢存在的因营养元素不均衡、毒性抑制和微生物种类较少等导致氢气产率较低的局限性,不同类型的底物厌氧共发酵制氢技术得以开发,然而现阶段仍然存在过程机理不清楚和关键工艺参数不明确等问题。本文综述了有机废弃物厌氧共发酵制氢的必要性、优点及主要影响因素,归纳了不同有机废弃物混合比、有机负荷、发酵温度、水力停留时间、初始pH以及固液比、搅拌方式和反应器类型等关键工艺参数特征及其范围,分析比较了不同有机废弃物厌氧共发酵体系的氢气浓度及产率、发酵液pH、氨氮和挥发性脂肪酸及其组成等工艺特性,总结了产氢功能菌群及其产氢特性及不稳定系统特征微生物。随后指出了目前研究存在的一些不足,并对其在底物利用范围及其预处理、过程机理、技术完善及其综合评估等方面的研究与应用前景进行了展望,为有机废弃物厌氧共发酵制氢技术的研发与应用提供依据。     

Platform chemical production from food wastes using a biorefinery concept

According to the Food and Agricultural Organization (FAO), one‐third of food produced globally for human consumption (nearly 1.3 billion tons) is lost along the food supply chain. Food waste has often been incinerated with other combustible municipal wastes for possible recovery of heat or other forms of energy, and the residual ash is disposed of in landfills. However, incineration is not cost‐effective, and can potentially cause air pollution. Therefore, green technology is urgently needed for appropriate management of food waste with a focus on material recovery. Due to its organics‐ and nutrients‐rich nature, food waste could be viewed as a useful resource for production of high‐value platform chemicals through fermentation. Compared with animal feed or traditional fuel for transportation, platform chemicals obviously have higher economic value, i.e. more profitable. Recently, technologies for production of value added bio‐products (e.g. organic acids, biodegradable polymers, etc.) from various kinds of food wastes have gained more and more interest. This review attempts to examine the state of the art of the fermentation technologies of food waste for production of platform chemicals, with emphasis on the Asia‐Pacific region. © 2014 Society of Chemical Industry     

Continuous ethanol production by the synchronous saccharification and fermentation using food wastes

The synchronous saccharification and fermentation (SSF) by continuous fill and draw method was investigated in order to develop a continuous ethanol fermentation process using the food wastes (FW) available among Korea’s organic wastes. The activity of the hydrolytic enzymes was maintained constantly in the continuous culture by their intermittent addition together with medium exchange. The concentrations of reducing sugar in the culture were maintained at a steady state by regulating supplemented enzyme concentration and exchange rate of medium, reflecting on the consumption rate of reducing sugar caused by the fermentation. When the temperature of the SSF was maintained at the fixation of 35 °C, which enabled us to perform both enzymatic hydrolysis and enzyme fermentation simultaneously, the rate of reducing sugar consumption was 3.61 g/L-hr. For the enzymatic saccharification of FW, when 0.01 BGU as Viscozyme/g-FW and 0.05 AGU as Spirizyme Plus/g-FW were used, the production rate of reducing sugar was 3.93 g/L-hr, indicating a little higher rate of production than that of consumption. A decompression device with ethanol condensing ability was used to continuously pull out ethanol from the culture broth at −600 mmHg, where the ethanol evaporation ability would be maximized and the water evaporation minimized during the process. As a result of the continuous SSF performance, the reducing sugar concentration was maintained at around 30 g/L. The amylase activity was maintained at 8.93±2.17 U/mL. During a 352 hour culture, the whole ethanol productivity was 2.24 g/L-hr, indicating a considerable productivity compared with the other result reported in the continuous SSF.     

Conversion efficiency of glucose/xylose mixtures for ethanol production using Saccharomyces cerevisiae ITV01 and Pichia stipitis NRRL Y‐7124

BACKGROUND: Efficient conversion of glucose/xylose mixtures from lignocellulose is necessary for commercially viable ethanol production. Oxygen and carbon sources are of paramount importance for ethanol yield. The aim of this work was to evaluate different glucose/xylose mixtures for ethanol production using S. cerevisiae ITV‐01 (wild type yeast) and P. stipitis NRRL Y‐7124 and the effect of supplying oxygen in separate and co‐culture processes. RESULTS: The complete conversion of a glucose/xylose mixture (75/30 g L^?1) was obtained using P. stipitis NRRL Y‐7124 under aerobic conditions (0.6 vvm), the highest yield production being Y_p/s = 0.46 g g^?1, volumetric ethanol productivity Q_pmax = 0.24 g L^?1 h^?1 and maximum ethanol concentration P_max = 34.5 g L^?1. In the co‐culture process and under aerobic conditions, incomplete conversion of glucose/xylose mixture was observed (20.4% residual xylose), with a maximum ethanol production of 30.3 g L^?1, ethanol yield of 0.4 g g^?1 and Q_pmax = 1.26 g L^?1 h^?1. CONCLUSIONS: The oxygen present in the glucose/xylose mixture promotes complete sugar consumption by P. stipitis NRRL Y‐7124 resulting in ethanol production. However, in co‐culture with S. cerevisiae ITV‐01 under aerobic conditions, incomplete fermentation occurs that could be caused by oxygen limitation and ethanol inhibition by P. stipitis NRRL Y‐7124; nevertheless the volumetric ethanol productivity increases fivefold compared with separate culture. Copyright © 2011 Society of Chemical Industry     

Pilot-scale production of bacterial cellulose by a spherical type bubble column bioreactor using saccharified food wastes

Bacterial cellulose (BC) was produced by Acetobacter xylinum KJ1 in a modified airlift-type bubble column bioreactor, which had a low shear stress and high oxygen transfer rate (k _L a). Saccharified food wastes (SFW) were used as the BC production medium due to its low cost. An aeration rate of 1.2 vvm (6 L/min) was tentatively determined as the optimal aeration condition in a 10 L spherical type bubble column bioreactor, by analysis of the oxygen transfer coefficient. When 0.4% agar was added, the BC production reached 5.8 g/L, compared with 5.0 g/L in the culture without the addition of agar. The BC productivity was improved by 10% in the addition of 0.4% agar into the SFW medium. Then, by conversion of a linear velocity of 0.93 cm/sec, from the relationship between the linear velocity and oxygen transfer rate, 1.0 vvm (30 L/min) was determined as an optimal aeration condition in a 50 L spherical type bubble column reactor. Using SFW medium, with the addition of 0.4% agar, and air supplied of 1.0 vvm, 5.6 g/L BC was produced in the 50 L spherical type bubble column bioreactor after 3 days of cultivation, which was similar to that produced in the 10 L bioreactor. In conclusion, the addition of agar, a viscous polysaccharide, into SFW medium is effective for the production of BC, and this scale-up method is very useful for the mass production in a 50 L spherical type bubble column bioreactor by decreasing the shear stress and increasing the k _L a.     

Kinetics of Bioethanol Production Employing Mono‐ and Co‐Cultures of Saccharomyces cerevisiae and Pichia stipitis

The kinetics of bioethanol production using mono‐ and co‐cultures of Saccharomyces cerevisiae and Pichia stipitis with glucose, xylose, and glucose‐xylose sugar mixtures were investigated. A MATLAB® program was formulated for simulation of experimental results in order to get predicted values of ethanol production and sugar consumption and for kinetic parameter estimation. Kinetic parameters implied less extent of substrate and/or product inhibition when the co‐culture scheme of immobilized S. cerevisiae and free P. stipitis was employed for fermentation of mixed sugars. In addition, a high ethanol yield was achieved by applying this co‐culture strategy to wheat straw hydrolysates.     

Bio-gas production by co-fermentation from the brown algae,Laminaria japonica

In this study, the optimization of bio-gas produced from Laminaria japonica through co-fermentation using hydrolysis and bio-gas production microorganisms was investigated. Bio-gas production was increased by using a mixed culture with Clostridium butyricum and Erwinia tasmaniensis, and the total hydrogen and methane levels were 327.47% and 354.99% higher, respectively. When lower oxygen contents were used in the flask, the bio-gas production yield increased. The optimual E/C ratio was determined to be 1/1, and the hydrogen and methane gas production levels under these conditions were 356.03 mL/L and 2243.59 mL/L, respectively.     

葡萄糖和木糖共发酵的产氢特性

引言化石能源面临枯竭,石油价格不断攀升,摆脱对化石能源的依赖是国内外亟待解决的重大问题。氢气因热值高、可再生且燃烧后无污染,成为21世纪最理想的能源。在众多制取氢气的方法中,厌氧发酵制氢反应条件温和,设备简单,而且可利用的原料来源广泛,从而引起了广泛的关注。     

Bioaccumulation and biosorption of copper(II) and chromium(III) from aqueous solutions by Pichia stipitis yeast

BACKGROUND: Bioaccumulation and biosorption by Pichia stipitis yeast has not yet been explored. This paper evaluates, for the first time, the use of both viable and nonviable P. stipitis yeast to eliminate Cu(II) and Cr(III) from aqueous solutions. The effect of Cu(II) and Cr(III) ions on the growth and bioaccumulation properties of adapted and nonadapted biomass is investigated as a function of initial metal concentration. Binding capacity experiments using nonviable biomass are also performed as a function of temperature. RESULTS: The addition of Cu(II) and Cr(III) had a significant negative effect on the growth of yeast. Nonadapted cells could tolerate Cu(II) and Cr(III) ions up to a concentration of 75 ppm. The growth rate of nonadapted and adapted cells decreased with the increase in Cu(II) and Cr(III) concentration. Adapted P. stipitis biomass was capable of removing Cu(II) and Cr(III) with a maximum specific uptake capacity of 15.85 and 9.10 mg g⁻¹, respectively, at 100 ppm initial Cu(II) and Cr(III) concentration at pH 4.5. Adsorption data on nonviable cells were found to be well modeled by the Langmuir and Temkin isotherms. The maximum loading capacity of dry biomass predicted from Langmuir isotherm for Cu(II) and Cr(III) at 20 °C were 16.89 and 19.2 mg g⁻¹, respectively, at pH 4.5. Biosorptive capacities were dependent on temperature for Cu(II) and Cr(III) solutions. CONCLUSION: Cu(II)‐ and Cr(III)‐adapted cells grow and accumulate these ions at high ratios. On the other hand, nonviable P. stipitis was found to be an effective biosorbent for Cu(II) and Cr(III) biosorption. Copyright © 2008 Society of Chemical Industry     

Ethanol and chitosan production from wheat hydrolysate by Mucor hiemalis

BACKGROUND: High glucose and ethanol tolerance is among the most important requirements of ethanol‐producing microorganisms. The purpose of this study was evaluation of filamentous fungus Mucor hiemalis for ethanol production from wheat and starch hydrolysates with high glucose concentration. RESULTS: The results showed high tolerance of the fungus in fermentation of the hydrolyzates with high glucose concentrations (as high as 190 g L^?1). Interestingly, increasing the glucose concentration from 15 to 190 g L^?1 was accompanied by enhancement of initial sugar uptake rate. Ethanol was the most important metabolite obtained during all fermentations and its concentration reached over 50 g L^?1. Beside ethanol, chitosan was another valuable product of the process. Glucosamine, a precursor of chitosan, made up 37.3–46.7% of the cell wall of this fungus. CONCLUSIONS: M. hiemalis is a promising microorganism for simultaneous production of ethanol and chitosan from substrates with high sugar concentrations. © 2012 Society of Chemical Industry     

Solid-state production of esterase using fish processing wastes by Bacillus altitudinis AP-MSU

The bacterium Bacillus altitudinis AP-MSU, able to produce esterase was isolated from the gut of marine fish Sardinella longiceps. The esterase production was investigated in solid-state fermentation experiment using various fish processing waste meal. Among the tested fish processing wastes, red grouper waste emerged as the best source for higher esterase production. The suitable surfactant and triglyceride identified to increase the lipase production was neem oil. Effect of individual carbon and nitrogen sources supplementation on esterase production revealed that fructose and peptone aided the higher esterase production than the other tested carbon and nitrogen sources. The suitable concentration of sodium chloride for higher esterase production was at 5%. Effect of surfactants and trace elements on esterase production showed that Tween 20 and zinc sulphate, respectively produced maximum amount of esterase. The effect of physical parameters on lipase production revealed that 50 °C temperature and pH 7–8 were optimum for higher esterase production. Statistical optimization with Plackett–Burman design showed that neem oil, NaCl and fructose were found to be the most predictive factors for esterase production by this strain.     

Determination of the stoichiometry and critical oxygen tension in the production culture of bacterial cellulose using saccharified food wastes

The stoichiometry of the entire reaction in a 50 L scaled-up production culture of bacterial cellulose (BC), using saccharified food wastes (SFW), was analyzed in this study. The stoichiometric analysis was carried out using the chemical formula, yield, degrees of reduction of the major components, and the respiratory quotient (RQ). Based on the stoichiometric analysis, the amounts of substrate, oxygen supply and BC production etc., were able to be predicted. In addition, the amount of energy generated in the culture was predicted based on the oxygen consumption via the stoichiometric analysis. The stoichiometry of BC production using SFW in a 50 L large scale reactor will be useful as a standard for mass production of the culture. The stoichiometric analysis can also help the designers of reactors decide on the boiler capacity and oxygen supply for a large scale bioreactor system. The OUR (oxygen uptake rate) of Acetobacter xylinum KJ1 in a 12 hour-age cultivation was 0.21 mg DO/L·min, from which the critical DO concentration was suggested to be maintained above 3.10 ppm to prevent oxygen limitation during the BC production culture. The results indicated that pure oxygen should be supplied during the exponential phase, where DO depletion was observed. An ascertainment experiment, with the addition of pure oxygen into the culture system, showed BC production of 7.37 g/L, which was considerable productivity.     

Fuel ethanol production from concentrated food waste hydrolysates in immobilized cell reactors by Saccharomyces cerevisiae H058

BACKGROUND: Continuous ethanol fermentation of concentrated food waste hydrolysates has been studied. The process was carried out in an immobilized cell reactor with beads of calcium‐alginate containing immobilized Saccharomyces cerevisiae H058 at temperature 30 °C and pH 5.0. RESULTS: The total residual sugar decreased with increase of hydraulic retention time (HRT) under various reducing sugar concentrations. Ethanol production by immobilized cells increased with increase in HRT, regardless of the substrate concentrations employed. The highest ethanol concentration of 89.28 g L^?1 was achieved at an HRT of 5.87 h and reducing sugar concentration of 200 g L^?1. At an HRT of 1.47 h, the maximum volumetric ethanol productivity of 49.88 g L^?1 h^?1 and the highest ethanol yield of 0.48 g g^?1 were achieved at reducing sugar concentration of 160 and 200 g L^?1, respectively. The difference between the fresh and the 30‐day Ca–alginate immobilized cell was also shown by scanning electronic micrographs of beads taken from their outer and inner surfaces. CONCLUSIONS: Continuous ethanol production from concentrated food waste hydrolysates using immobilized yeast cells is promising in view of the high ethanol productivity obtained at relatively high conversion and excellent reactor stability. Copyright © 2011 Society of Chemical Industry     

微生物利用废弃物产生絮凝剂的研究与应用

作者介绍了微生物利用废弃物如麦芽根、水产排水等产生絮凝剂的研究与应用.同时还介绍了一种以微生物利用水产排水产生的絮凝剂处理该水产排水,所得沉淀物用作饲料成分的方法.     

Ceramics from mining by-products and alumina production wastes

The possibility of obtaining chemically stable ceramics in plastic molding from pastes based on comprehensive use of mining by-products (plagioporphyry, quartz-biotite shale), alumina production wastes (red mud), and polymineral clay was demonstrated. The mechanism of enhancing paste sintering on addition of finely disperse grog-flux and increasing the alkali resistance of the material (to 95%) in molding of the crystalline hematite-anorthite-quartz system was examined. __________ Translated from Steklo i Keramika, No. 2, pp. 17–20, February, 2007.     

Osmoprotectants enhance methane production from the anaerobic digestion of food wastes containing a high content of salt

BACKGROUND: Treatment and disposal of Korean food waste encounter technical difficulties due to a high‐salt problem. In order to increase methane production from food waste by using osmoprotectants, which are known to overcome osmotic stresses in many plants and other organisms, osmoprotectants including glycine betaine, choline, carnitine and trehalose were added to salt‐containing food wastes for anaerobic digestion. RESULTS: For NaCl‐amended food wastes containing 10 and 35 g L^?1 NaCl, glycine betaine and choline increased methane production by about twofold compared to food waste without any osmoprotectants. For non‐washed food waste containing 11.6 g L^?1 NaCl, glycine betaine increased methane production by about sixfold. Among these osmoprotectants, glycine betaine was the most effective for increasing methane productivity in anaerobic digestion of food waste with salinity. Analysis of glycine betaine in cell extracts using high‐performance liquid chromatography showed that glycine betaine accumulated in the cells of anaerobic sludge. CONCLUSION: Osmoprotectants significantly enhanced methanization of high‐salt food wastes by alleviating the salt‐induced physiological stresses in microorganisms. The application of osmoprotectants provided an effective substitute for other conventional methods to reduce inhibitory effects of high salt, such as dilution and co‐digestion. Copyright © 2008 Society of Chemical Industry     

加快生物质废弃物吸附增强制可再生氢气

作为全球性的优质能源载体,氢的主要生产方式包括碳氢化合物（例如天然气、煤炭和生物质）的热化学过程以及使用电力来源与可再生能源（如风能或太阳能等）的水电解过程。目前的水电解技术在大规模制氢方面经济竞争力亟待提升。本文指出：为了在2060年实现碳中和,迫切需要开发绿氢制备新技术,大力发展可再生制氢和低碳制氢。具有碳捕集、利用和封存的碳氢化合物低碳制氢（蓝色）技术将占重要地位,随后逐步转向可再生制氢（绿色）,并有望全面实现零碳制氢,进而对长期低碳化社会的发展至关重要。文章提出我国生物质资源非常丰富,但生物质废弃物制氢的技术成熟度仍然较低,迫切需要开发从生物质中高效生产可再生氢气的新技术,以显著提高氢气产量并降低成本;吸附增强反应代表了一种可用于可持续生产氢的有前景的新技术;氢气的产率和纯度可以通过过程强化得到显著提高,制氢过程的强化可以在多功能反应器中实现,其中重整和/或气化、水煤气变换和CO₂移除步骤可将重整/水煤气变换反应催化剂和CO₂捕集剂混合而集成到一个反应器中。最后指出：由于该过程潜力巨大,因此应助推耦合气化和吸附增强反应过程从生物质废弃物中生产可再生氢气的工艺过程,以加快推进碳中和进程。