不溶性着色蔗渣木聚糖检测木聚糖酶活性*

蔗渣木聚糖经1.4-丁二醇二环氧甘油醚与染料气巴蓝3GA交联形成不溶性着色固体。这种着色蔗渣木聚糖在pH4-8范围内表现稳定,用于评价木聚糖酶活性及在平板上检测产酶微生物具有简捷而灵敏的效果。     

The influence of pH and dilution rate on continuous production of xylitol from sugarcane bagasse hemicellulosic hydrolysate by C. guilliermondii

Continuous fermentation of sugarcane bagasse hemicellulosic hydrolysate by the yeast Candida guilliermondii FTI 20037 was used for xylitol production from xylose. Experiments were carried out in a reactor with 1.25 l of treated hydrolysate, at 30 °C and 300 rpm. A 2² full-factorial central composite design was employed for experimental study and analysis of the results. A statistical analysis of the results showed that the effects of the pH and dilution rate (D), the interactions between these variables and the second-order effect of D on the xylitol volumetric productivity (Q_p) were significant at a 95% confidence level. The second-order effect of pH was also significant at a 90% confidence level. The k_La effect on the Q_p was not significant. A volumetric productivity of 0.68 g/l h, representing 95.8% of the predicted value (0.72 g/l h), was obtained.     

甘蔗渣接枝四乙烯五胺制备治理印染废水的新型吸附剂

论文通过在甘蔗渣(sugarcane bagasse,SB)中引入四乙烯五胺获得改性甘蔗渣(modified sugarcane bagasse,MSB),制备出对有机染料伊红和重金属离子Cu²⁺、Cr³⁺均有较好吸附能力的吸附剂,并研究了pH、温度、初始浓度等因素对吸附的影响.结果表明当伊红溶液pH为6时,MSB的吸附量比SB提高了18倍,对金属Cu²⁺ 、Cr³⁺的吸附量也大大高于SB.染料伊红的吸附过程可以用Langmuir 型吸附等温线较好地模拟,由方程可得25℃下伊红的最大吸附量为399.04 mg·g^-1,MSB对伊红的吸附行为符合伪二级吸附动力学模型.实验结果显示改性甘蔗渣(modified sugarcane bagasse,MSB)是一种吸附性能优异的吸附剂,用于处理印染废水与制革废水有较好的应用前景.     

Aroma compounds produced by Kluyveromyces marxianus in solid state fermentation on a packed bed column bioreactor

Studies were carried out for the production of aroma compounds by Kluyveromyces marxianus grown on cassava bagasse in solid state fermentation using packed bed reactors, testing two different aeration rates. Respirometric analysis was used to follow the growth of the culture. Headspace analysis of the culture by gas chromatography showed the production of 11 compounds, out of which nine were identified. Ethyl acetate, ethanol and acetaldehyde were the major compounds produced. Lower aeration rate (0.06l h^–1 g^–1 of initial dry matter) increased total volatile (TV) production and the rate of production was also increased at this aeration rate. Using an aeration rate of 0.06l h^–1 g^–1 maximum TV concentrations were reached at 24 h and at 40 h with 0.12l h^–1 g^–1.     

Efficient conversion of sugarcane stalks into ethanol employing low temperature alkali pretreatment method

An alternative route for bio-ethanol production from sugarcane stalks (juice and bagasse) featuring a previously reported low temperature alkali pretreatment method was evaluated. Test-tube scale pretreatment-saccharification experiments were carried out to determine optimal LTA pretreatment conditions for sugarcane bagasse with regard to the efficiency of enzymatic hydrolysis of the cellulose. Free fermentable sugars and bagasse recovered from 2 kg of sugarcane stalks were jointly converted into ethanol via separate enzymatic hydrolysis and fermentation (SHF). Results showed that 98% of the cellulose present in the optimally pretreated bagasse was hydrolyzed into glucose after 72-h enzymatic saccharification using commercially available cellulase and β-glucosidase preparations at relatively low enzyme loading. The fermentable sugars in the mixture of the sugar juice and the bagasse hydrolysate were readily converted into 193.5 mL of ethanol by Saccharomyces cerevisiae within 12h, achieving 88% of the theoretical yield from the sugars and cellulose.     

Enhanced saccharification kinetics of sugarcane bagasse pretreated in 1-butyl-3-methylimidazolium chloride at high temperature and without complete dissolution

Dissolution of bagasse with 1-butyl-3-methylimidazolium chloride at high temperatures (110-160 °C) is investigated as a pretreatment process for saccharification and fermentation based biofuel production. Material balances are reported and used along with enzymatic saccharification data to identify optimum pretreatment conditions (150 °C for 90 min). At all pretreatment temperatures, dissolved and reprecipitated material is enriched in cellulose, has a low crystallinity and the cellulose component is easily and quantitatively hydrolysed (100%, 3h, 15 FPU). At pretreatment temperatures ≤ 150 °C, the undissolved material has only slightly lower crystallinity than the starting. At pretreatment temperatures ≥ 150 °C, the undissolved material has low crystallinity and when combined with the dissolved material has a saccharification rate and extent similar to completely dissolved material. Complete dissolution is not necessary to maximise saccharification efficiency at temperatures ≥ 150 °C.     

Delignification of sugarcane bagasse using glycerol-water mixtures to produce pulps for saccharification

This paper describes the organosolv delignification of depithed bagasse using glycerol–water mixtures without a catalyst. The experiments were performed using two separate experimental designs. In the first experiment, two temperatures (150 and 190 °C), two time periods (60 and 240 min) and two glycerol contents (20% and 80%, v/v) were used. In the second experiment, which was a central composite design, the glycerol content was maintained at 80%, and a range of temperatures (141.7–198.3 °C) and time (23–277 min) was used. The best result, obtained with a glycerol content of 80%, a reaction time of 150 min and a temperature of 198.3 °C, produced pulps with 54.4% pulp yield, 7.75% residual lignin, 81.4% delignification and 13.7% polyose content. The results showed that high contents of glycerol tend to produce pulps with higher delignification and higher polyoses content in relation to the pulps obtained from low glycerol content reactions. In addition, the proposed method shows potential as a pretreatment for cellulose saccharification.     

The effects of four different pretreatments on enzymatic hydrolysis of sweet sorghum bagasse

Four pretreatment processes including ionic liquids, steam explosion, lime, and dilute acid were used for enzymatic hydrolysis of sweet sorghum bagasse. Compared with the other three pretreatment approaches, steam-explosion pretreatment showed the greatest improvement on enzymatic hydrolysis of the bagasse. The maximum conversion of cellulose and the concentration of glucose obtained from enzymatic hydrolysis of steam explosion bagasse reached 70% and 25 g/L, respectively, which were both 2.5 times higher than those of the control (27% and 11 g/L). The results based on the analysis of SEM photos, FTIR, XRD and NMR detection suggested that both the reduction of crystallite size of cellulose and cellulose degradation from the Iα and Iβ to the Fibril surface cellulose and amorphous cellulose were critical for enzymatic hydrolysis. These pretreatments disrupted the crystal structure of cellulose and increased the available surface area, which made the cellulose better accessible for enzymatic hydrolysis.     

Production of bioethanol, methane and heat from sugarcane bagasse in a biorefinery concept

The potential of biogas production from the residues of second generation bioethanol production was investigated taking into consideration two types of pretreatment: lime or alkaline hydrogen peroxide. Bagasse was pretreated, enzymatically hydrolyzed and the wastes from pretreatment and hydrolysis were used to produce biogas. Results have shown that if pretreatment is carried out at a bagasse concentration of 4% DM, the highest global methane production is obtained with the peroxide pretreatment: 72.1 L methane/kg bagasse. The recovery of lignin from the peroxide pretreatment liquor was also the highest, 112.7 ± 0.01 g/kg of bagasse. Evaluation of four different biofuel production scenarios has shown that 63-65% of the energy that would be produced by bagasse incineration can be recovered by combining ethanol production with the combustion of lignin and hydrolysis residues, along with the anaerobic digestion of pretreatment liquors, while only 32-33% of the energy is recovered by bioethanol production alone.