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1.
Kwon YJ  Ma AZ  Li Q  Wang F  Zhuang GQ  Liu CZ 《Bioresource technology》2011,102(17):8099-8104
A newly isolated thermotolerant ethanologenic yeast strain, Issatchenkia orientalis IPE 100, was able to produce ethanol with a theoretical yield of 85% per g of glucose at 42 °C. Ethanol production was inhibited by furfural, hydroxymethylfurfural and vanillin concentrations above 5.56 g L−1, 7.81 g L−1, and 3.17 g L−1, respectively, but the strain was able to produce ethanol from enzymatically hydrolyzed steam-exploded cornstalk with 93.8% of theoretical yield and 0.91 g L−1 h−1 of productivity at 42 °C. Therefore, I. orientalis IPE 100 is a potential candidate for commercial lignocelluloses-to-ethanol production.  相似文献   

2.
先进固体发酵技术(ASSF)生产甜高粱乙醇   总被引:7,自引:0,他引:7  
介绍了利用高产能源作物甜高粱生产燃料乙醇的先进固态发酵(ASSF)技术,从甜高粱茎秆保存、菌种、反应器,到固体发酵过程的数学模拟和工程放大进行了系统研究。筛选出高效产乙醇的菌种CGMCC1949,固体发酵时间低于30 h,乙醇收率高于92%;优选出贮存甜高粱茎秆的有效方法,通过抑菌处理,厌氧贮存200 d糖分损失小于5%;对固态发酵过程进行了数学模拟,设计并优化了固体发酵设备,成功进行了工程放大试验,并且基于ASPEN软件对该技术进行了技术经济评价,结果表明ASSF法生产甜高粱乙醇在技术、工程和经济上均具有充分的可行性和明显优势。  相似文献   

3.
Switchgrass (Panicum virgatum) was subjected to hydrothermolysis pretreatment and then used to study the effect of enzyme loading and temperature in a simultaneous saccharification and fermentation (SSF) with the thermotolerant yeast strain Kluyveromyces marxianus IMB3 at 8% solid loading. Various loadings of Accellerase 1500 between 0.1 and 1.1 mL g(-1) glucan were tested in SSF at 45 °C (activity of enzyme was 82.2 FPU mL(-1)). The optimum enzyme loading was 0.7 mL g(-1) glucan based on the six different enzyme loadings tested. SSFs were performed at 37, 41 and 45 °C with an enzyme loading of 0.7 mL g(-1) glucan. The highest ethanol concentration of 22.5 g L(-1) was obtained after 168 h with SSF at 45 °C, which was equivalent to 86% yield. Four different batch and fed-batch strategies were evaluated using a total solid loading of 12% (dry basis). About 32 g L(-1) ethanol was produced with the four strategies, which was equivalent to 82% yield.  相似文献   

4.
Ethanol production from sweet sorghum juice by Saccharomyces cerevisiae NP01 was investigated under very high gravity (VHG) fermentation and various carbon adjuncts and nitrogen sources. When sucrose was used as an adjunct, the sweet sorghum juice containing total sugar of 280 g l−1, 3 g yeast extract l−1 and 5 g peptone l−1 gave the maximum ethanol production efficiency with concentration, productivity and yield of 120.68 ± 0.54 g l−1, 2.01 ± 0.01 g l−1 h−1 and 0.51 ± 0.00 g g−1, respectively. When sugarcane molasses was used as an adjunct, the juice under the same conditions gave the maximum ethanol concentration, productivity and yield with the values of 109.34 ± 0.78 g l−1, 1.52 ± 0.01 g l−1 h−1 and 0.45 ± 0.01 g g−1, respectively. In addition, ammonium sulphate was not suitable for use as a nitrogen supplement in the sweet sorghum juice for ethanol production since it caused the reduction in ethanol concentration and yield for approximately 14% when compared to those of the unsupplemented juices.  相似文献   

5.
Tri-substrate mixture of Prosopis juliflora (PJ), red gram husk (RGH) and cotton seed cake (CSC) has been studied for the production of lipase (E.C. 3.1.1.3) using Aspergillus niger MTCC 872 in solid state fermentation. Simplex centroid mixture design (SCMD) was implemented to optimize the tri-substrate mixture composition consisting of PJ, RGH and CSC. Mixture taken in the ratio of 6.66:1.66:1.66 for PJ:RGH:CSC has shown highest lipase activity of 212.20 ± 6.36 U/gds at 30 °C, 7 pH and 70 % initial moisture content (v/w). Sequential optimization of physical parameters was done using the central composite face-centered design (CCFD). The optimum mixture composition has shown the highest lipase activity of 269.87 ± 8.09 U/gds at 35 °C, 7 pH and 70 % initial moisture content (v/w). ANOVA analysis for SCMD and CCFD confirms the model’s significance with R2 values of 0.9989 and 0.968. A 1.27 fold increased lipase activity was obtained after physical parameters optimization. Large scale production using 1 kg substrate was carried out in tray bioreactor with different bed heights and the highest lipase activity of 208.79 ± 6.26 U/gds was obtained. This study signifies the enhancement of lipase production using substrate PJ for lipase production along with the other agricultural residues.  相似文献   

6.
In this study ethanol was produced from corn stover pretreated by alkaline and acidic wet oxidation (WO) (195 degrees C, 15 min, 12 bar oxygen) followed by nonisothermal simultaneous saccharification and fermentation (SSF). In the first step of the SSF, small amounts of cellulases were added at 50 degrees C, the optimal temperature of enzymes, in order to obtain better mixing condition due to some liquefaction. In the second step more cellulases were added in combination with dried baker's yeast (Saccharomyces cerevisiae) at 30 degrees C. The phenols (0.4-0.5 g/L) and carboxylic acids (4.6-5.9 g/L) were present in the hemicellulose rich hydrolyzate at subinhibitory levels, thus no detoxification was needed prior to SSF of the whole slurry. Based on the cellulose available in the WO corn stover 83% of the theoretical ethanol yield was obtained under optimized SSF conditions. This was achieved with a substrate concentration of 12% dry matter (DM) acidic WO corn stover at 30 FPU/g DM (43.5 FPU/g cellulose) enzyme loading. Even with 20 and 15 FPU/g DM (corresponding to 29 and 22 FPU/g cellulose) enzyme loading, ethanol yields of 76 and 73%, respectively, were obtained. After 120 h of SSF the highest ethanol concentration of 52 g/L (6 vol.%) was achieved, which exceeds the technical and economical limit of the industrial-scale alcohol distillation. The SSF results showed that the cellulose in pretreated corn stover can be efficiently fermented to ethanol with up to 15% DM concentration. A further increase of substrate concentration reduced the ethanol yield significant as a result of insufficient mass transfer. It was also shown that the fermentation could be followed with an easy monitoring system based on the weight loss of the produced CO2.  相似文献   

7.
Whey permeate (WP) was used efficiently for production of mosquitocidal toxin by Bacillus sphaericus 2362 (B. sphaericus 2362) and the Egyptian isolate, B. sphaericus 14N1 (B. sphaericus 14N1) under both submerged and solid state fermentation conditions. Under submerged fermentation, high mosquitocidal activity was produced by B. sphaericus 2362 and B. sphaericus 14N1 at 50-100% and 25-70% WP, respectively. Initial pH of WP was a critical factor for toxin production by both tested organisms. The highest toxicity was obtained at initial pH 7. Egyptian isolate, B. sphaericus 14N1 was tested for growth and toxin production under solid state fermentation conditions (SSF) by using WP as moistening agent instead of distilled water. The optimum conditions for production of B. sphaericus 14N1 on wheat bran-WP medium were 10 g wheat bran/250 ml flask moistened with 10-70% WP at 50% moisture content, inoculum size ranged between 17.2 × 107 and 34.4 × 107 and 6 days incubation under static conditions at 30 °C. Preliminary pilot-scale production of B. sphaericus 14N1 under SSF conditions in trays proved that wheat bran-WP medium was efficient and economic for industrial production of mosquitocidal toxin by B. sphaericus.  相似文献   

8.
This paper investigates the correlation between mycelial age and fatty acid biosynthesis. The correlation was investigated by analyzing the lipid composition lengthwise the mycelium of the oleaginous fungus Mortierella isabellina, a potential producer of γ-linolenic acid (GLA). Young mycelia were rich in polar lipids (glycolipids plus sphingolipids and phospholipids), while neutral lipid content increased in aged mycelia. In young mycelia, each polar lipid fraction contained almost 40% (w/w) polyunsaturated fatty acids (PUFAs), but this content decreased to less than 30% (w/w) in aged mycelia. On the other hand, PUFA content in neutral lipids fluctuated slightly with age. These results indicate that PUFA biosynthesis is favored in young, fast growing mycelia, while it decreases significantly in aged mycelia. This trend was also observed when we grew M. isabellina on pear pomace, an agro-industrial waste. Pear pomace cultures yielded significant amounts of lipid, which reached 12% (w/w) in dry fermented mass. The produced lipid was rich in GLA and the maximum GLA content in dry fermented mass was 2.9 mg/g.  相似文献   

9.
The thermotolerant yeast Hansenula polymorpha ferments glucose and xylose to ethanol at high temperatures. However, H. polymorpha cannot utilize starchy materials or xylans. Heterologous amylolytic and xylanolytic enzymes have to be expressed in this yeast to provide for utilization and growth on starch and xylan. Genes SWA2 and GAM1 from the yeast Schwanniomyces occidentalis, encoding α-amylase and glucoamylase, respectively, were expressed in H. polymorpha. The expression was achieved by integration of the SWA2 and GAM1 genes under the strong constitutive promoter of the H. polymorpha glyceraldehyde-3-phosphate dehydrogenase gene (HpGAP) into H. polymorpha genome. Resulting transformants acquired the ability to grow on a minimal medium containing soluble starch as a sole carbon source. Ethanol production at high-temperature fermentation from starch by the recombinant strains was up to 10 g/L. The XYN2 gene encoding endoxylanase of the fungus Trichoderma reseei was expressed in H. polymorpha. Co-expression of xlnD gene coding for β-xylosidase of the fungus Aspergillus niger and the XYN2 gene in H. polymorpha was achieved by integration of these genes under control of the HpGAP promoter. Resulting transformants were capable of growth and alcoholic fermentation on a minimal medium supplemented with birchwood xylan as a sole carbon source at 48 °C.  相似文献   

10.
Exopectinase (exo-p) and endopectinase (endo-p) production by Aspergillus niger CH4 in solid state culture was studied at initial glucose concentrations of 100, 250, 350 and 450 g/l. The highest activity of exo-p (35 U/g) was produced at 72 and 120 h in the medium containing 100 and 250 g glucose/l, respectively. The maximum endo-p activity (9 U/g) was produced at 72 h in the medium with 250 g glucose/l. The reduction in pectinase production at 350 and 450 g/l initial glucose concentration was due neither to repression of the synthesis of the enzyme nor to the glucose consumption rate of the strain but due to a drastic drop in pH of the medium.S. Solis-Pereyra, E. Favela-Torres, M. Gutiérrez-Rojas, G. Saucedo-Castañeda and G. Viniegra-González are with the Departamento de Biotecnologia, Universidad Autónoma Metropolitana, A.P. 55-535, C.P. 09340, México D.F., México; S. Roussos is with the Laboratoire de Biotechnologie, ORSTOM, B.P. 5045, 34032, Montpellier Cedex, France, and P. Gunasekaran is with the Department of Microbial Technology, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625-021, India.  相似文献   

11.
Mixed sugars from tropical maize stalk juice were used to carry out butanol fermentation with Clostridium beijerinckii NCIMB 8052. Batch experiments employing central composite design (CCD) and response surface methodology (RSM) optimization were performed to evaluate effects of three factors, i.e. pH, initial total sugar concentration, and agitation rate on butanol production. Optimum conditions of pH 6.7, sugar concentration 42.2 g/L and agitation rate 48 rpm were predicted, under which a maximum butanol yield of 0.27 g/g-sugar was estimated. Further experiments demonstrated that higher agitation facilitated acetone production, leading to lower butanol selectivity in total acetone–butanol–ethanol (ABE). While glucose and fructose are more preferable by C. beijerinckii, sucrose can also be easily degraded by the microorganism. This study indicated that RSM is a useful approach for optimizing operational conditions for butanol production, and demonstrated that tropical maize, with high yield of biomass and stalk sugars, is a promising biofuel crop.  相似文献   

12.
Bacillus licheniformis was grown for 48 h at 37°C in solid state fermentation; a maximum of 1.7 × 1011 spores/g dry substrate were obtained using rice straw powder (300 g/kg) and wheat bran (700 g/kg) supplemented with glucose (40 g/kg), peptone (20 g/kg), yeast extract (20 g/kg), KH2PO4 (10 g/kg) and CaO (5 g/kg) with an initial moisture content of 65%.  相似文献   

13.
A major challenge associated with the fermentation of lignocellulose-derived hydrolysates is improved ethanol production in the presence of fermentation inhibitors, such as acetic and formic acids. Enhancement of transaldolase (TAL) and formate dehydrogenase (FDH) activities through metabolic engineering successfully conferred resistance to weak acids in a recombinant xylose-fermenting Saccharomyces cerevisiae strain. Moreover, hybridization of the metabolically engineered yeast strain improved ethanol production from xylose in the presence of both 30 mM acetate and 20 mM formate. Batch fermentation of lignocellulosic hydrolysate containing a mixture of glucose, fructose and xylose as carbon sources, as well as the fermentation inhibitors, acetate and formate, was performed for five cycles without any loss of fermentation capacity. Long-term stability of ethanol production in the fermentation phase was not only attributed to the coexpression of TAL and FDH genes, but also the hybridization of haploid strains.  相似文献   

14.
The production of extracellular α-amylase by thermotolerant Bacillus subtilis was studied in solid state fermentation (SSF). The effect of wheat bran (WB) and rice husk (RH) was examined. The appropriate incubation period, moisture level, particle size and inoculum concentration was determined. Maximum yields of 159,520 and 21,760 U g−1 were achieved by employing WB and RH as substrates in 0.1 M phosphate buffer at pH 7 with 30% initial moisture content at 24 and 48 h. Particle size and inoculum concentration were found to be 1000 μm, 20% and 500 μm, 15% for WB and RH, respectively. Enzyme yield was 7.3-fold higher with WB medium compared with RH.  相似文献   

15.
Summary A solid state fermentation (SSF) process for the production of lignin peroxidase was optimized to enhance enzyme production by Phanerochaete chrysosporium. Optimization of the corncob SSF medium caused a significant reduction in fermentation time to give maximum lignin peroxidase yield. Supplementation of the SSF medium by low concentrations of peptone, yeast extract and Tween-80 enhanced lignin peroxidase production. Maximum yield of lignin peroxidase was 13.7 U/gds (units per gram dry substrate) noted after 5 days of SSF with 70% moisture and 20% (v/w) inoculum.  相似文献   

16.
Yao L  Wang T  Wang H 《Bioresource technology》2011,102(19):9199-9205
The feasibility of using soy skim, a co-product of the aqueous processing of soybeans, in ethanol production from corn was evaluated. Specific growth rates were compared when Saccharomyces cerevisiae was grown in soy skim and peptone-yeast extract media supplemented with glucose. Such soy skim was proved to be a good nitrogen source for yeast growth. Next, fermentation of dry-ground corn to ethanol using soy skim as the media was simulated on 1.5-L scale. Replacing water with soy skim increased the initial ethanol production rates by 4-32% while final ethanol yield was about 39 g/100 g dry corn, similar to the result when water was used. Solid and protein contents in the finished beer increased with the addition of soy skim. Thus, replacing water in corn-ethanol fermentation with soy skim is feasible, and may improve the economics of both aqueous soybean processing and corn ethanol fermentation.  相似文献   

17.
Penicillium sp. X−1, isolated from decayed raw corn, produced high level of raw-starch-digesting glucoamylase (RSDG) under solid state fermentation (SSF). Maximum enzyme yield of 306.2 U g−1 dry mouldy bran (DMB) was obtained after 36 h of culture upon optimized production. The enzyme could hydrolyse both small and large granule starches but did not adsorb on raw starch. The enzyme exhibited maximum activity at 65°C and pH 6.5, which provided an opportunity of synergism with α-amylase. It significantly hydrolysed 15% (w/v) raw corn starch slurry in synergism with the commercial α-amylase and a degree of hydrolysis of 92.4% was obtained after 2 h of incubation.  相似文献   

18.
The quantitative effects of temperature, pH and time of fermentation were investigated on simultaneous saccharification and fermentation (SSF) of ethanol from sago starch with glucoamylase (AMG) and Zymomonas mobilis ZM4 using a Box–Wilson central composite design protocol. The SSF process was studied using free enzyme and free cells and it was found that with sago starch, maximum ethanol concentration of 70.68 g/l was obtained using a starch concentration of 140 g/l, which represents an ethanol yield of 97.08%. The optimum conditions for the above yield were found to be a temperature of 36.74 °C, pH of 5.02 and time of fermentation of 17 h. Thus by using the central composite design, it is possible to determine the accurate values of the fermentation parameters where maximum production of ethanol occurs.  相似文献   

19.
The production of cellulolytic enzymes by Aspergillus niger on lignocellulosic substrates groundnut fodder, wheat bran, rice bran and sawdust in solid state fermentation in a laboratory scale was compared. Czapek Dox liquid broth amended with cellulose (0.5%) was used to moisten lignocellulosic solid supports for cultivation of Aspergillus niger. The production of filter paperase, carboxymethyl cellulase and -glucosidase were monitored at daily intervals for 5 days. The peak production of the enzymes occurred within 3 days of incubation. Among solid supports used in the study, wheat bran was the best solid matrix followed by groundnut fodder in production of cellulolytic enzymes in solid state fermentation. Groundnut fodder supported significant production of FPase (2.09 FPU/g), CMCase (1.36 U/g) and -glucosidase activity (0.0117 U/g) in solid state fermentation. Considerable secretion of protein (5.10 mg/g) on groundnut fodder at peak time interval 1st day of incubation was recorded.  相似文献   

20.
Given that N-methylmorpholine-N-oxide (NMMO) is a promising alternative for the pretreatment of lignocelluloses, a novel process for ethanol and biogas production from wood was developed. The solvent, NMMO, is concentrated by multistage evaporation, and the wood is pretreated with the concentrated NMMO. Thereafter, ethanol is produced by the non-isothermal simultaneous saccharification and fermentation (NSSF) method, which is a rapid and efficient process. The wastewater is treated by upflow anaerobic sludge blanket (UASB) digester for rapid production of biogas. The process was simulated by Aspen plus®. Using mechanical vapor recompression for evaporators in the pretreatment and multi-pressure distillation columns, the energy requirements for the process were minimized. The economical feasibility of the developed biorefinery for five different plant capacities was studied by Aspen Icarus Process Evaluator. The base case was designed to utilize 200,000 tons of spruce wood per year and required M€ 58.3 as the total capital investment, while the production cost of ethanol is calculated to be €/l 0.44.  相似文献   

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