Simultaneous saccharification and fermentation of wheat bran flour into ethanol using coculture of amylotic Aspergillus niger and thermotolerant Kluyveromyces marxianus

Studies on simultaneous saccharification and fermentation (SSF) of wheat bran flour, a grain milling residue as the substrate using coculture method were carried out with strains of starch digesting Aspergillus niger and nonstarch digesting and sugar fermenting Kluyveromyces marxianus in batch fermentation. Experiments based on central composite design (CCD) were conducted to maximize the glucose yield and to study the effects of substrate concentration, pH, temperature, and enzyme concentration on percentage conversion of wheat bran flour starch to glucose by treatment with fungal α-amylase and the above parameters were optimized using response surface methodology (RSM). The optimum values of substrate concentration, pH, temperature, and enzyme concentration were found to be 200 g/L, 5.5, 65°C and 7.5 IU, respectively, in the starch saccharification step. The effects of pH, temperature and substrate concentration on ethanol concentration, biomass and reducing sugar concentration were also investigated. The optimum temperature and pH were found to be 30°C and 5.5, respectively. The wheat bran flour solution equivalent to 6% (w/V) initial starch concentration gave the highest ethanol concentration of 23.1 g/L after 48 h of fermentation at optimum conditions of pH and temperature. The growth kinetics was modeled using Monod model and Logistic model and product formation kinetics using Leudeking-Piret model. Simultaneous saccharificiation and fermentation of liquefied wheat bran starch to bioethanol was studied using coculture of amylolytic fungus A. niger and nonamylolytic sugar fermenting K. marxianus.     

INCREASE IN PHYTASE SYNTHESIS DURING CITRIC PULP FERMENTATION

Citric pulp bran was used for the first time as substrate for phytase synthesis under solid-state fermentation. An A. niger FS3 phytase strain was applied in optimization studies. A Plackett-Burman screening design identified significant physicochemical variables. These preselected variables were subsequently optimized using a central composite rotational design (CCRD). The maximum phytase production was achieved with the following optimum variables: 30°C temperature, 65% initial moisture content, 0.3 M Na-citrate buffer concentration, initial pH 5.0, and 1.5% urea concentration. An overall 4.3-fold improvement in phytase production was successfully achieved.     

Study of simultaneous saccharification and fermentation for steam exploded wheat straw to ethanol

Although simultaneous saccharification and fermentation (SSF) has been investigated extensively, the optimum condition for SSF of wheat straw has not yet been determined. Dilute sulfuric acid impregnated and steam explosion pretreated wheat straw was used as a substrate for the production of ethanol by SSF through orthogonal experiment design in this study. Cellulase mixture (Celluclast 1.5 l and β-glucosidase Novozym 188) were adopted in combination with the yeast Saccharomyces cerevisiae AS2.1. The effects of reaction temperature, substrate concentration, initial fermentation liquid pH value and enzyme loading were evaluated and the SSF conditions were optimized. The ranking, from high to low, of influential extent of the SSF affecting factors to ethanol concentration and yield was substrate concentration, enzyme loading, initial fermentation liquid pH value and reaction temperature, respectively. The optimal SSF conditions were: reaction temperature, 35°C; substrate concentration, 100 g·L⁻¹; initial fermentation liquid pH, 5.0; enzyme loading, 30 FPU·g⁻¹. Under these conditions, the ethanol concentration increased with reaction time, and after 72 h, ethanol was obtained in 65.8% yield with a concentration of 22.7 g·L⁻¹. __________ Translated from Chemical Engineering (China), 2007, 35(12): 42–45 [译自: 化学工程]     

Protease production by Aspergillus oryzae in solid‐state fermentation using agroindustrial substrates

BACKGROUND: An inexpensive and readily available agroindustrial substrate such as rice bran can be used to produce cheap commercial enzymes by solid‐state fermentation. This work investigates the production of food‐grade proteases by solid‐state fermentation using readily available Thai rice bran. RESULTS: A local strain of Aspergillus oryzae (Ozykat‐1) was used to produce proteases. Rice bran used alone proved to have poor substrate morphology (insufficient porosity) for satisfactory solid‐state fermentation. A certain amount of wheat bran was necessary to improve the morphology of the substrate. The following variables affected protease production: substrate composition, initial moisture content and initial pH. A high protease activity (∼1200 U g⁻¹ dry solids) was obtained on a substrate that had a wheat bran to rice bran ratio of 0.33 by dry weight, a moisture content of 50%, initial pH of 7.5, and incubation temperature of 30 °C. CONCLUSION: Nutritionally, rice bran used alone was as good a substrate as mixed bran for producing protease, but rice bran had poor morphological characteristics for consistent fermentation. A substrate that had a wheat bran to rice bran ratio of 0.33 by dry weight was best for producing protease. Copyright © 2008 Society of Chemical Industry     

蒸汽爆破麦草同步糖化发酵转化乙醇的研究

近年来对木质生物资源同步糖化发酵转化乙醇的研究较多,但是,麦草同步糖化发酵转化乙醇的最佳工艺条件还未确定。文中采用正交试验设计的方法,对在混合酶(纤维素酶Celluclast 1.5 1,β-葡萄糖苷酶Novozym 188)与酿酒酵母菌作用下,稀硫酸催化的蒸汽爆破麦草原料同步糖化发酵转化乙醇的工艺条件进行研究,详细讨论了反应温度、底物质量浓度、发酵液pH值、纤维素酶浓度对乙醇质量浓度和得率的影响。结果表明,工艺条件对乙醇质量浓度和得率的影响程度由高到低依次为:底物质量浓度、纤维素酶浓度、发酵液pH值、反应温度。最佳工艺条件为反应温度35℃,底物质量浓度100 g/L,发酵液pH值5.0,纤维素酶浓度30 FPU/g。在此条件下,随着反应时间的延长,乙醇质量浓度持续上升。反应72 h后,乙醇质量浓度和得率分别达到22.7 g/L和65.8%。     

橡子粉同步液化糖化产燃料乙醇的发酵条件优化

以除去单宁的橡子粉为原料,应用活性干酵母同步液化糖化发酵(SLSF)制备燃料乙醇,并通过单因素试验和正交试验优化发酵条件。结果表明,同步液化糖化发酵技术适用于橡子粉发酵制备燃料乙醇;发酵的最佳条件为:除去单宁的橡子粉20 g,料液比为1:3(g:mL),淀粉酶100 U/g,糖化酶3 750 U/g,活性干酵母1.50%;在30 ℃静止发酵120 h,发酵液中的乙醇质量浓度达到106.5 g/L,橡子淀粉的乙醇转化率达到89.36 %。采用橡子粉发酵法制备燃料乙醇与以玉米等粮食作物为原料制备的燃料乙醇质量浓度相当,可以替代粮食作物生产燃料乙醇。     

瘤胃菌与丁醇菌共生发酵麸皮生产丁醇

寻求瘤胃纤维素降解菌群NLH151与丁醇菌zr11共生发酵麸皮生产丁醇的最佳工艺条件。考察了接种方式、共培养温度、pH值等因素对纤维素降解率及丁醇生产能力的影响,得出了2种菌最佳共生培养的发酵条件。共生发酵时,麸皮质量浓度为20 g/L,共培养温度为33℃,pH值为6.0—6.5,瘤胃菌NLH151与丁醇菌zr11的接种量(体积分数)分别控制在15%和8%,瘤胃菌接入24 h后接入丁醇菌,共发酵48 h,总溶剂质量浓度可达到10.33 g/L,其中丁醇为7.8 g/L。该研究为利用农业废弃物进行新能源的开发提供了实验依据。     

Sago starch saccharification and simultaneous ethanol fermentation by amyloglucosidase and Zymomonas mobilis

Simultaneous saccharification and ethanol fermentation (SSF) of sago starch was studied using amyloglucosidase (AMG) and Zymomonas mobilis. The optimal concentration of AMG and operating temperature for the SSF process were found to be 0.5% (v/w) and 35°C, respectively. Under these conditions with 150 g dm^?3 sago starch as a substrate, the final ethanol concentration obtained was 69.2 g dm^?3 and ethanol yield, Y_P/S, 0.50 g g^?1 (97% of theoretical yield). Sago starch in the concentration range of 100–200 g dm^?3 was efficiently converted into ethanol. When compared to a two-step process involving separate saccharification and fermentation stages, the SSF reduced the total process time by half.     

Study of simultaneous saccharification and fermentation for steam exploded wheat straw to ethanol

Although simultaneous saccharification and fermentation (SSF) has been investigated extensively, the optimum condition for SSF of wheat straw has not yet been determined. Dilute sulfuric acid impregnated and steam explosion pretreated wheat straw was used as a substrate for the production of ethanol by SSF through orthogonal experiment design in this study. Cellulase mixture (Celluclast 1.5 l and ?-glucosidase Novozym 188) were adopted in combination with the yeast Saccharomyces cerevisiae AS2.1. The effects of reaction temperature, substrate concentration, initial fermentation liquid pH value and enzyme loading were evaluated and the SSF conditions were optimized. The ranking, from high to low, of influential extent of the SSF affecting factors to ethanol concentration and yield was substrate concentration, enzyme loading, initial fermentation liquid pH value and reaction temperature, respectively. The optimal SSF conditions were: reaction temperature, 35°C; substrate concentration, 100 g·L^-1; initial fermentation liquid pH, 5.0; enzyme loading, 30 FPU·g^-1. Under these conditions, the ethanol concentration increased with reaction time, and after 72 h, ethanol was obtained in 65.8% yield with a concentration of 22.7 g·L^-1.     

Effect of simultaneous saccharification and fermentation conditions of native triticale starch on the dynamics and efficiency of process and composition of the distillates obtained

BACKGROUND: Among ethanol production technologies, attention should be focused towards simultaneous saccharification and fermentation of native starch with enzymes capable of its degradation without prior gelatinization. Selection of process conditions makes it possible to achieve high efficiency of the process and to reduce the costs of the production of ethanol. RESULTS: This study determined the effect of hydrolysis conditions of native triticale starch based on the results of their fermentation and concentration of by‐products in the distillates obtained. The pre‐activation of starch with acid α‐amylase is not necessary for the proper conduct and efficiency of saccharification and fermentation of native triticale starch. Beneficial impact on the synthesis of ethanol was afforded by the treatment of mashes with protease preparation (EC 3.4.21.62) (Bacillus licheniformis). Raising the pH of mashes from 3.6 to 4.8 did not improve the ethanol yield. Process conditions had a diversified impact on concentration of by‐products in the raw spirits obtained. CONCLUSION: Under the optimal conditions found in these experiments 63.01 ± 0.33–63.56 ± 0.33 L of absolute ethanol was obtained from 100 kg of starch. Simultaneous saccharification and fermentation of the native starch raw materials, especially without pre‐activation of starch, can simplify the process and improve the economic index in the alcohol‐distilling industry. © 2012 Society of Chemical Industry     

Ethanol-Herstellung mit Bakterien

Ethanol production with bacteria . Strains of Saccharomyces cerevisiae have mostly been used for the production of ethanol from sugar by yeasts. Recently it was shown that the bacterium Zymomonas mobilis has some advantages compared to yeast for the production of industrial alcohol. Compared to traditional yeast fermentation, ethanol yield is about 5% higher than with yeast, since less sugar is incorporated into cell material by this bacterium. Like yeast, Zymomonas mobilis has remarkably high ethanol tolerance which enables the bacterium to produce ethanol concentrations of more than 13 vol.-% from sugar solutions of appropriate concentration. Investigations of the spectrum of lipids present have shown that this bacterium contains large quantities of hopanoids which are presumably of significance for the stabilization of cell membranes in the presence of ethanol. Since the cost of the sugar greatly influences the profitability fraction formed in the production of glucose syrup from wheat flour was investigated. It was shown that after enzymatic saccharification of this waste starch the glucose was efficiently fermented to ethanol by Zymomonas mobilis. It is planned to broaden the substrate spectrum of Zymomonas mobilis by gene cloning techniques so that in future pentoses, e. g. xylose or arabinose, can also be fermented to ethanol by this organism.     

Simultaneous saccharification and fermentation of pretreated Antigonum leptopus (Linn) leaves to ethanol

Simultaneous saccharification and fermentation (SSF) of alkaline hydrogen peroxide pretreated Antigonum leptopus (Linn) leaves to ethanol was optimized using cellulase from Trichoderma reesei QM‐9414 (Celluclast® from Novo) and Saccharomyces cerevisiae NRRL‐Y‐132 cells. Contrary to the saccharification optima (2.5% w/v substrate concentration, 50 °C, 4.5 pH, 40 FPU cellulase g⁻¹ substrate and 24 h reaction time), the SSF optima was found to be somewhat different (10% w/v substrate, 40 °C, 100 FPU cellulase g⁻¹ substrate and 72 h). Better ethanol yields were obtained with SSF compared with the traditional saccharification and subsequent fermentation (S&F) and when the cellulase was supplemented with β‐glucosidase. © 1999 Society of Chemical Industry     

白腐菌预处理甘蔗渣促进水解的研究

利用一株产木质素降解酶的白腐菌Ceripriopsis sp.,以固态发酵形式对甘蔗渣进行预处理,选择性降解其中的木质素,从而提高其水解效率。甘蔗渣固态发酵过程中,发酵温度、培养基成分、含水量和初始pH值对酶活和糖收率都有影响。含水量是对糖收率影响最大的因素,其次是麸皮添加量,再次是温度,而初始pH值影响最小。甘蔗渣固态发酵的最佳条件为:培养基中含水量为80%,麸皮含量为5%,初始pH=4.0时28℃发酵14d,获得的糖产率最大,达20.6%。     

Co-Cultivation of Aspergillus niger and Trichoderma reesei Enables Efficient Production of Enzymes for the Hydrolysis of Wheat Bran

Agro-residues like wheat bran may be a useful carbon source for fermentation processes. However, due to their composition, hydrolysis appears complex. A co-cultivation process was established with the two fungi A. niger and T. reesei for the production of an adapted mixture of enzymes for hydrolysis. This enzyme solution reached a higher space-time yield of sugars during the hydrolysis of wheat bran compared to enzymes from respective monocultures, demonstrating the potential of this co-culture for the production of complementary enzyme mixtures for the hydrolysis of wheat bran.     

利用野生淀粉资源——木薯、芭蕉芋发酵生产丙酮

提出了以木薯、芭蕉芋替代玉米作为生产丙酮的发酵原料 ,先后利用豆饼、玉米粉等 10余种辅料进行了实验 ,以改善木薯、芭蕉芋原料蛋白质不足[4 ] 。并通过实验筛选了适合木薯、芭蕉芋发酵的优良菌株。实验表明 ,以木薯、芭蕉芋为原料 ,只需添加少量辅料 ,利用筛选出的优良菌株发酵 ,结果可达到现有玉米发酵水平     

A kinetic model for enzymatic wheat starch saccharification

A kinetic model describing the enzymatic saccharification of wheat starch by a mixture of α‐amylase and amyloglucosidase has been developed. The model describes the influence of pH, glucose inhibition and starch and enzyme concentration. The results of experimental saccharification under different physical conditions, eg pH and temperature, were used to determine the parameters in the model. The dominant enzyme in the mixture was amyloglucosidase and the maximum rate of saccharification due to this enzyme was found to be optimal at pH 5, and increased Five‐Fold when the temperature was increased from 30 to 55 °C. Saccharification due to the action of amyloglucosidase was inhibited by the glucose produced and simulation showed that the maximum rate of saccharification decreased by 58% at a starch concentration of 140 g dm⁻³ compared with a starch concentration much less than 110 g dm⁻³ where the effect of glucose inhibition was negligible. © 2000 Society of Chemical Industry     

Biotechnological production of lactic acid integrated with potato wastewater treatment by Rhizopus arrhizus

This paper describes a feasibility study of a for lactic acid production integrated with are treatment of wastewater from an industrial starch plant. Rhizopus oryzae two strains, Rhizopus arrhizus and Rhizopus oligosporus were tested with respect to their capability to carry out simultaneous saccharification and fermentation to lactic acid using potato wastewater. Rhizopus arrhizus DAR 36017 was identified as a suitable strain that demonstrated a high capacity for starch saccharification and lactic acid synthesis. The optimal conditions, in terms of pH, temperature and starch concentration, for lactic acid production were determined. The selected fungal strain grew well in a pH range from 3.0 to 7.0. The addition of CaCO₃10 g dm^?3 maintained the pH at 5.0–6.0 and significantly enhanced lactic acid production. Kinetic study revealed that almost complete starch saccharification and a lactic acid yield of 450g kg^?1 could be achieved in 20 h and 28 h cultivation, respectively. The maximum lactic acid production 21 g dm^?3 and mycelial biomass (1.7 g dm^?3) were obtained at 30 °C. Besides the multiple bioproducts, total removal of suspended solids and 90% reduction of COD were achieved in a single no‐aseptic operation. Copyright © 2003 Society of Chemical Industry     

固态发酵植物药提取残渣生产饲料蛋白工艺条件

以某制药厂双黄连制剂生产过程中产生的废弃药渣作为研究对象,在对药渣成份进行了全分析的基础上,利用正交实验法研究了混菌固态发酵植物药提取残渣生产饲料蛋白工艺参数的不同,对发酵产物蛋白含量的影响。结果表明:以40g药渣,35g玉米浆,8g玉米面,15g麸皮,2g尿素组成固态发酵培养基,产朊假丝酵母与扣囊拟内孢霉的菌种配比为2∶1时,最佳发酵条件为:发酵温度30℃,接种量15%,含水量65%,培养时间60h。在最佳发酵条件下,发酵产物的粗蛋白含量可达29.98%。以废弃药渣为主要原料发酵生产蛋白饲料是切实可行的。     

甘薯渣发酵乙醇的工艺研究

研究了甘薯渣同步糖化发酵乙醇的最佳工艺条件,考察了不同酵母接种量、水料比、发酵时间和 pH 对甘薯渣发酵乙醇的影响。通过单因素、正交试验,最终确定同步糖化发酵乙醇的最佳条件为：接种量1.4%,水料比25：1,发酵时间108h,pH 5.5。在此条件下乙醇得率为34.78%,糖利用率为73.76%。     

Acid and enzymatic saccharification of agricultural mixed polymers for alcohol production

The paper reports the evaluation of potentials of acid (HCl and H₂SO₄) and enzymatically (cellulase) saccharified corncob, groundnut shell, sugarcane bagasse and wheat straw biopolymers for ethanol production. Of the three yeast isolates tested, Saccharomyces cerevisiae var. ellipsoideus was found to be most efficient, closely followed by Kluyveromyces marxianus NCYC 179 in its ability to ferment enzymatically hydrolysed mash of all the substrates tested to ethanol. However, S. cerevisiae NCYC 240 and acid hydrolysed agricultural polymers were found to be a poor organism and poor substrates, respectively, for ethanol fermentation. The order of ethanol production on substrate basis was corncob > wheat straw > sugarcane bagasse > groundnut shell biomass biopolymer. An incubation period of 24 h was found optimum for the optimal production of ethanol by S. cerevisiae var. ellipsoideus in both acid and enzymatically hydrolysed agricultural residues.