固态发酵生产裂褶菌多糖的动力学研究

对固态发酵生产裂褶菌多糖的动力学过程进行了研究,基于Logistic方程和Luedeking-Pirct方程建立了裂褶菌固态发酵生成裂褶菌多糖的菌体生长、多糖合成和底物消耗的动力学模型,并对模型参数进行了非线性回归。结果表明,裂褶菌多糖的产量与菌体生长速率和底物消耗量均有关系,最大比生长速率为0.7385 d-1。模型预测值和实验值有良好的拟合性,菌体生长、多糖合成、底物消耗3条曲线的相关指数(R值)分别为0.99256、0.99163和0.98835。表明此动力学模型可以较好地定量描述裂褶菌多糖的固态发酵生产过程,对工业化生产具有实际指导意义。     

Z5-G菌生产聚β-羟基丁酸发酵动力学模型

研究了Z5 G菌株在 3L搅拌发酵罐中以蔗糖为碳源分批发酵生产聚β 羟基丁酸 (PHB)的生长特性。在Lo gistic方程和Luedeking Piret方程的基础上,建立了Z5 G菌发酵过程中菌体生长、基质消耗、产物形成的动力学模型。应用MathCAD软件处理实验数据和模型,拟合出所有模型参数,建立了动力学模型,经过验证模型预测值和实验值吻合较好,表明此动力学模型对指导PHB的发酵生产具有实际意义。     

以高产量、高产率、高生产强度为目标的发酵过程优化技术

以高产量、高底物转化率和高生产强度为目标,综合运用微生物反应计量学、生化反应和传递动力学、生物反应器工程及代谢工程理论,开发了:(1)基于微生物反应计量学的培养环境优化技术;(2)基于微生物代谢特性的分阶段培养技术;(3)基于反应动力学模型的优化技术;(4)基于代谢通量分析的优化技术;(5)基于系统观点的生物反应系统优化技术。将这些技术广泛应用于多种产品的发酵过程优化研究中并取得了成功。在此基础上总结出“简化、定量化、模型化和阶段化”的发酵过程优化基本原理,这一基本原理对提高我国发酵工业技术水平、促进生物食品产业的健康发展将起重要作用。     

pH值控制下γ-氨基丁酸分批发酵动力学模型

在3.7 L发酵罐中研究短乳杆菌CGMCC NO.1306控制pH=5.0发酵生产γ-氨基丁酸(GABA)的过程。结果表明,γ-氨基丁酸的发酵过程大致分为菌体生长和产物合成2个阶段。基于Logistic方程和改进的Luedek ing-P iret方程,分2个阶段建立了控制pH=5.0的细胞生长、底物消耗以及GABA合成动力学模型,运用MATLAB 6.0软件处理实验数据和模型,拟合出描述发酵过程的模型参数。经验证,模型的拟合结果和实验值吻合较好,表明此动力学模型对指导GABA的发酵生产具有实际意义。     

黄原胶发酵的动力学模型及过程模拟

在5L 通气式搅拌发酵罐中,非溶氧限制的条件下,实验测定了间歇黄原胶发酵的过程数据,并建立了描述这一过程的动力学方程。菌体生长动力学方程(dC_b)/(dt)=0.2675C_b(1(-C_b/1.75))底物(碳源)消耗的动力学方程-(dC_s)/(dt)=0.14C_b(1-(C_b/1.75))+0.5806C_b~2/(1+0.06326C_p)产物(黄原胶)生成动力学方程(dC_p)/(dt)=0.4452C_b~2/(1+0.06326C_p)利用上述动力学方程能较好地描述生长期和稳定期的黄原胶发酵行为。     

芭蕉芋燃料乙醇同步固态糖化发酵技术及其经济可行性

芭蕉芋是一种可选择的酒精发酵原料.为了评价芭蕉芋酒精固态发酵工艺,实验应用Plackett-Burman设计对芭蕉芋固态蒸煮糖化工艺进行研究,进一步确定了酒精固态发酵工艺条件,最后对芭蕉芋固体发酵法生产燃料乙醇进行技术经济可行性分析.结果表明,固态糖化芭蕉芋水解产物DE值达到96.34%.添加30%芭蕉芋秆茎和20%稻壳,固态发酵醅酒精浓度为10.1%(体积分数).固态同时糖化发酵过程没有可发酵糖的缺失,减少了酒精生产过程时间,节约了能源.发酵过程没有废水排放,酒精产率达到29.4%,技术经济分析说明固态法芭焦芋燃料乙醇生产可行.     

土曲霉固态发酵lovastatin的动力学研究

对Aspergillus terreus ATCC 20542固态发酵产lovastatin的过程进行了研究,根据发酵过程中菌体生长和产物生成等规律,建立了土曲霉固态发酵的过程动力学模型,并对模型进行了参数拟合和验证.模型在一定程度上揭示了lovastatin 发酵代谢过程的特征,可以用于分析固体发酵过程.     

影响固态发酵速率的因素及其动力学

论述了固态发酵过程中基质的形态特性、基质含水量、通气速率与气体组成、发酵温度诸因素对发酵速率的影响；探讨了固态发酵过程动力学模型及其特征。     

Rhizobium sp.N613合成胞外多糖的发酵动力学研究

对Rhizobium sp.N613合成胞外多糖(REPS)的分批发酵过程和发酵动力学进行了研究.应用Logistic方程和Luedeking-Piret方程,得到了描述Rhizobium sp.N613菌体生长、REPS合成和底物消耗的动力学模型.模型反映了该菌株合成REPS分批发酵过程的动力学特征,模型值与实验数据拟合良好.对Rhizobium sp.N613发酵动力学模型和合成REPS的生理学特性进行了分析,优化了合成REPS的发酵工艺,补料分批发酵实验结果表明,REPS产量从8.21 g·L-1提高到 11.31 g·L-1.     

肌苷发酵过程的动力学研究

采用枯草杆菌(Bacillus Subtilis)突变株,以葡萄糖为碳源进行间歇发酵研究,得到肌苷发酵过程受底物抑制的动力学关系。在肌苷代谢机理简化的基础上推导建立了工程上适用的菌体增殖动力学方程(dx)/(dt)=0.00266(Sx)/(20.3+s+s~2/76.4+I/6.03)肌苷生成的动力学方程为(dp)/(dt)=0.1791((Sx)/(67.76+s))-8.40(dx)/(dt)基质糖消耗的动力学方程为-(ds)/(dt)=(1/1.017)((dx)/(dt))+(1/0.1207)((dp)/(dt))+(0.3188x)     

真菌发酵酒精废弃物合成单细胞蛋白基质及菌种筛选

为了优选利用酒精废弃物生产单细胞蛋白（single cell protein,SCP）的最佳基质和菌种组合,从而实现其高值化利用,本文选取了黄酒加工废弃物（黄酒糟和米浆水）以及木薯酒精加工废弃物（木薯原糟和木薯酒糟上清液）4种基质作为发酵底物,并以产朊假丝酵母（Candida utilis）和白地霉（Geotrichum candidum）2种常见菌种作为筛选对象,通过摇瓶发酵实验,考察不同基质对菌种产SCP的影响,同时对比不同菌种利用酒精废弃物发酵合成SCP的能力,从而选出最优发酵基质和菌株。结果表明,以黄酒糟和米浆水按质量分数6%配比,同时接种产朊假丝酵母和白地霉进行混菌发酵4天时,SCP的产率及产量均达最优值,干物质产率可达3.91,产量可达90.22g/L,粗蛋白含量可达53.3%,且发酵产物中的氨基酸成分齐全,作为蛋白饲料具有良好的应用前景。     

周期刺激固态发酵生产纤维素酶

木质纤维素是世界上最丰富的可再生性资源,而开发利用木质纤维素的关键就是纤维素酶。固态发酵法生产纤维素酶产量高、成本低,优于液态发酵法,但因为固态发酵反应器比较独特,因此未能迅速普及。生化工程国家重点实验室研制了新型周期刺激固态反应器进行规模化生产,产品质量符合市场的要求。     

Bioethanol production from wheat straw by the thermotolerant yeast Kluyveromyces marxianus CECT 10875 in a simultaneous saccharification and fermentation fed-batch process

Solid content in the simultaneous saccharification and fermentation (SSF) broth should be as high as possible in order to reach higher ethanol concentration. In this work, several feeding strategies for ethanol production from steam-exploded wheat straw by Kluyveromyces marxianus CECT 10875 have been studied with the aim of obtaining higher ethanol concentrations. Previous fermentability tests as well as SSF processes showed the difficulty of using the slurry for ethanol production under the studied conditions. Notwithstanding, fed-batch SSF processes with water-insoluble solids (WIS) fraction resulted in better configuration, reaching the highest ethanol concentration (36.2 g/L) with an initial WIS content of 10% (w/v) and 4% (w/v) of substrate addition at 12 h, which meant 20% more ethanol when compared with batch SSF.     

Production and Application of Novel Sterol Esterases from <Emphasis Type="Italic">Aspergillus</Emphasis> Strains by Solid State Fermentation

Among numerous mesophilic fungi screened for sterol esterase activity followed by the esterification reaction between plant β-sitosterol and lauric acid in organic solvent, six Aspergillus strains were selected as the most active producers. These fungi had not been studied previously for sterol esterase production. The fungi were cultivated under solid state fermentation (SSF) conditions. The gently dried SSF cultures as such were tested in the esterification reactions, without any special enzyme isolation and purification (downstream) processes. All the six Aspergillus SSF preparations were able to synthesize sterol esters. Sterol esterase activity of these GRAS cleared Aspergillus strains was inducible by sterol ester supplementation to the SSF medium and showed remarkably different moisture optimum during growth as compared to the production of lipase (determined by pNP-palmitate). Genome analysis revealed that sterol esterase production might be a common feature of many Aspergillus species. The synthetic usefulness of the best SSF preparations of A. oryzae NRRL 6270 and A. sojae NRRL 6271 was demonstrated by synthesis of esters of plant sterols with lauric acid resulting in 45–63% conversions (GC) and 27–38% isolated yields of steryl laurates. The isomer preference of A. oryzae NRRL 6270 towards the 10E,12Z isomer of conjugated linoleic acid (CLA) in the esterification reaction with plant sterols was also determined.     

Comparison of bioethanol production of simultaneous saccharification & fermentation and separation hydrolysis & fermentation from cellulose-rich barley straw

Cellulose rich barley straw, which has a glucan content of 62.5%, followed by dilute acid pretreatment, was converted to bioethanol by simultaneous saccharification and fermentation (SSF). The optimum fractionation conditions for barley straw were an acid concentration of 1% (w/v), a reaction temperature of 158 °C and a reaction time of 15 min. The maximum saccharification of glucan in the fractionated barley straw was 70.8% in 72 h at 60 FPU/gglucan, while the maximum digestibility of the untreated straw was only 18.9%. With 6% content WIS (water insoluble solid) for the fractionated barley straw, 70.5 and 83.2% of the saccharification yield were in SHF and SSF (representing with glucose equivalent), respectively, and a final ethanol concentration of 18.46 g/L was obtained under the optimized SSF conditions: 34 °C with 15 FPU/g-glucan enzyme loading and 1 g dry yeast cells/L. The results demonstrate that the SSF process is more effective than SHF for bioethanol production by around 18%.     

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%。     

甲醇蛋白的生产应用及投资建议

介绍甲醇蛋白的生产和应用情况。通过对甲醇蛋白的成本估算，并和鱼粉价格比较，指出该产品暂时不具备投资价值。     

FED-BATCH SIMULTANEOUS SACCHARIFICATION AND FERMENTATION OF MICROWAVE/ACID/ALKALI/H2O2 PRETREATED RICE STRAW FOR PRODUCTION OF ETHANOL

The batch simultaneous saccharification and fermentation (SSF) of microwave/acid/alkali/H₂O₂ pretreated rice straw to ethanol was optimized using cellulase from Trichoderma reesei and Saccharomyces cerevisiae YC-097 cells prior to the fed-batch SSF studies. The batch SSF optima were 10% w/v substrate, 40°C, 15 mg cellulase/g substrate, initial pH 5.3, and 72 hours. Under the optimum conditions the ethanol concentration and its yield were 29.1 g/L and 61.3% respectively. Based on the optimal batch SSF, the fed-batch SSF was investigated and its operation parameters were optimized. Under its optimal conditions the ethanol concentration reached 57.3 g/L, while its productivity and yield were only slightly less than those in the batch SSF. This suggests that fed-batch SSF is a potential operation mode for effective ethanol production from microwave/acid/alkali/H₂O₂ pretreated rice straw.     

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.     

木质纤维生物质同步糖化发酵(SSF)生产乙醇的研究进展

综述了有关木质纤维生物质原料同步糖化发酵生产乙醇的最新研究进展和未来发展方向:同步糖化发酵是一种用于从木质纤维原料生产乙醇的工艺过程,此工艺的优点是酶水解与发酵同时进行,可以减少最终产物对酶水解的抑制作用,并减少投资成本,是最具发展潜力和优势的工艺之一。近年来在优化预处理工艺、降低纤维素酶成本以及己糖戊糖协同发酵等方面的研究都取得了长足的进步,其中以小麦秸秆为原料进行同步糖化发酵所得到的乙醇浓度接近40g/L。