康宁木霉固态发酵秸秆生产纤维素酶的研究

采用康宁木霉(Trichodermakoningii)固体发酵生产纤维素酶,研究了秸杆粉和麦麸用量、料水比、起始pH值、温度和时间对该菌株产纤维素酶活力的影响。结果表明,康宁木霉的适宜发酵条件为:秸秆∶麦麸=3∶2,料水比1∶2,培养温度28～30℃,起始pH5.5～6.0时产酶活力最高。在适宜培养条件下,发酵周期为72h,发酵液中FPA酶活为172.3μmol/h.mL。     

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。     

混菌固态发酵豆渣生产菌体蛋白的研究

对以豆渣为原料,利用混菌固态发酵技术生产菌体蛋白饲料工艺进行了研究。通过L9(3^4)正交试验考察了培养基组成、接种物配比、初始pH值以及培养温度等因素的影响。结果表明：当培养基组成为豆渣：麸皮=8：2,接种物配比为黑曲霉：绿色木霉：啤酒酵母：产朊假丝酵母=1：1：1：3,调节初始pH值5．5,32℃培养72h,豆渣粗蛋白质含量达到28．47％。     

中药丹皮残渣固态发酵产酶与糖化工艺的研究

利用绿色木霉菌对丹皮提取残渣固态发酵产纤维素酶。以纤维素酶的酶活为指标,丹皮残渣与麸皮的比例、(NH4)2SO4添加量、发酵时间、接种量、发酵温度及固液比为考查因素,采取先单因素后正交实验的方法选取最佳发酵工艺。结果表明,最佳发酵条件为:丹皮残渣与麸皮的比例为2.5∶2.5,(NH4)2SO4添加量3%,发酵时间12天,接种量20%,发酵温度30℃,固液比1∶1.2。丹皮渣固态发酵残渣进行糖化发酵,糖化率为7.6%。因此,丹皮提取残渣固态发酵产纤维素酶是可行的,且发酵后残渣可以直接进行糖化发酵。     

玉米种皮固态发酵绿色木霉生产纤维素酶的研究

通过以玉米种皮为基质对绿色木霉J98-06的固态发酵研究,选育得到一株高产纤维素酶菌株,其最适培养条件为:玉米种皮与麦麸质量比3:7,硫酸铵1.4%,K2HPO4 0.2%(质量分数),加水量为1:1.2～1.4(质量比),发酵温度30℃,发酵时间4天,产酶活力高达3865 U/g(干曲)。     

应用里氏木霉发酵制备纤维素酶固体曲的研究

应用本实验室筛选得到的纤维素酶高产菌株里氏木霉（Trichoderma reesei）150-1-1发酵制备纤维素酶固体曲,通过优化固态发酵培养基组成及发酵条件,制备得到纤维素酶活力较高的固体曲及粗酶液。实验结果表明,在原料量为10 g,麸皮与秸杆粉质量比为4：1,料液比为1：2.5,发酵时间为120 h,发酵温度为31℃,发酵起始pH值为5.5的条件下,应用里氏木霉150-1-1发酵得到的纤维素酶固体曲酶活力达到423.6 U/g。     

黄曲霉YZC产纤维素酶的固态发酵条件优化

为了提高黄曲霉YZC固态发酵所产纤维素酶的酶活力,采用单因素试验分别研究了碳源、氮源、氮源质量浓度、培养温度、培养时间、初始p H值、接种量对纤维素酶酶活的影响。优化后的固态发酵条件为：碳源为质量比3∶2的稻草粉与麸皮,氮源为NH4Cl,其质量浓度为10 g/L,培养温度为30℃,培养时间为7 d,初始p H值为4.0,接种量为20%。在此基础上,采用响应曲面法对影响纤维素酶活的3个因素包括氮源NH4Cl的质量浓度、培养时间、初始p H值进行优化,以期提高纤维素酶酶活。通过响应曲面分析得到滤纸酶活力与这三个因素的最优回归方程,确定滤纸酶活力最大时的最佳组合为NH4Cl质量浓度为8.5 g/L、培养时间为6.5 d、初始p H值为4.5,该条件下滤纸酶活力为10.87 IU/m L,是优化前的2.39倍,并与响应曲面拟合所得方程的预测值10.50 IU/m L符合良好。     

降解秸秆的纤维素酶产生菌的筛选及产酶条件研究

从土壤、霉变的农产品和实验室保存的真菌中筛选到15株产纤维素酶的菌株,其中绿色木霉T206产酶能力最强。利用液体发酵,研究了碳源、氮源、接种量、起始pH值、培养时间等对菌株产酶的影响,以及该菌株所产纤维素酶的种类。在最适条件下菌株培养96h后,羧甲基纤维素酶活(CMCA)最高达到7654.33U,是优化前酶活的1.7倍,滤纸酶活(FPA)达到1675.12U。     

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。     

N~＋注入诱变选育纤维素酶高产菌株及发酵产酶营养因子优化研究

应用低能氮离子（N＋）注入技术对纤维素酶产生菌里氏木霉（Trichoderma reesei）进行诱变选育,在能量为10 keV,注量为150×10^14和200×10^14N＋/cm^2的条件下分别筛选得到3株纤维素酶高产菌株,连续5代遗传稳定性实验结果表明,所得到的高产菌株遗传稳定性较好,羧甲基纤维素酶活力均提高到3.300 IU/mL以上,较出发菌株（2.698 IU/mL）提高了20.0%以上。采用Plackett-Burman实验设计法和旋转中心组合设计法系统地研究高产菌株150-1-1发酵营养因子组成,得到了纤维素酶产量随葡萄糖、麸皮和微晶纤维素等营养因子的变化规律及相应的响应面分析图。实验结果表明,葡萄糖、麸皮和微晶纤维素浓度与纤维素酶活存在显著的相关性,当葡萄糖浓度为4.9 g/L,麸皮浓度为23.0 g/L,微晶纤维素浓度为7.7 g/L时,150-1-1纤维素酶滤纸酶活力达到2.439 IU/mL,较优化前（2.000 IU/mL）提高了22.0%。     

珍贵橙色束丝放线菌固体发酵合成安丝菌素P-3的工艺探索

为了探索珍贵橙色束丝放线菌（Actinosynnema pretiosum）合成安丝菌素P-3（AP-3）的固体发酵培养条件的最佳工艺,利用农副产品（玉米淀粉、玉米粉、棉籽饼粉、豆粕、豆饼粉、菜籽饼粉、麦麸、米糠）作为固料,采用单因素实验和正交实验对固体发酵培养基组成及培养条件进行摸索。得到合成AP-3固体发酵的最佳培养基组分为：玉米淀粉、豆粕及棉籽饼粉的质量配比为1：1：1,红糖4%,玉米浆干粉2%,CaCl₂ 1%。最佳固体发酵工艺条件为：初始pH为7.5,培养温度28℃,固液比（质量比）为1：0.8,装量25g（250mL锥形瓶）,接种量150mL/kg,培养时间为7天,最优条件下AP-3的产量为（26.86±1.87）mg/kg（每千克培养基）。本研究为发酵合成安丝菌素提供了新的方法与思路。     

Pectinase enzyme-complex production by Aspergillus spp. in solid-state fermentation: A comparative study

A comparative evaluation of three Aspergillus species according to their pectinase production in solid-state fermentation was performed. Solid-state fermentation offers several potential advantages for enzyme production by fungal strains. Utilization of agricultural by-products as low-cost substrates for microbial enzyme production resulted in an economical and promising process. The pectinolytic enzyme activities of two Aspergillus sojae strains were compared to a known producer, Aspergillus niger IMI 91881, and to A. sojae ATCC 20235, which was re-classified as Aspergillus oryzae. Evaluation of polymethylgalacturonase and polygalacturonase activity was performed as well as exo- vs. endo-enzyme activity in the crude pectinase enzyme-complex of the mentioned strains. Furthermore, a plate diffusion assay was applied to determine the presence and action of proteases in the crude extracts. A. sojae ATCC 20235 with highest polymethylgalacturonase activity and highest polygalacturonase activity both exo- and endo-enzyme activity, is a promising candidate for industrial pectinase production, a group of enzymes with high commercial value, in solid-state fermentation processes. Beside the enzymatic assays a protein profile of each strain is given by SDS-PAGE electrophoresis and in addition species-specific zymograms for pectinolytic enzymes were observed, revealing the differences in protein pattern of the A. sojae strains to the re-classified A. oryzae.     

Fungal fucoidanase production by solid-state fermentation in a rotating drum bioreactor using algal biomass as substrate

Fucoidanase enzymes able to degrade fucoidan were produced by solid-state fermentation (SSF). The fermentation assays were initially carried out in a laboratory-scale rotating drum bioreactor, and two fungal strains (Aspergillus niger PSH and Mucor sp. 3P) and three algal substrates (untreated, autohydrolyzed, and microwave processed seaweed Fucus vesiculosus) were evaluated. Additionally, fermentations were carried out under rotational (10 rpm) and static conditions in order to determine the effect of the agitation on the enzyme production. Agitated experiments showed advantages in the induction of the enzyme when compared to the static ones. The conditions that promoted the maximum fucoidanase activity (3.82 U L^?1) consisted in using Mucor sp. 3P as fungal strain, autohydrolyzed alga as substrate, and the rotational system. Such conditions were subsequently used in a 10 times larger scale rotating drum bioreactor. In this step, the effect of controlling the substrate moisture during the enzyme production by SSF was investigated. Moreover, assays combining the algal substrate with an inert support (synthetic fiber) were also carried out. Fermentation of the autohydrolyzed alga with the moisture content maintained at 80% during the fermentation with Mucor sp. 3P gave the highest enzyme activity (9.62 U L^?1).     

Continuous solid-state fermentation as affected by substrate flow pattern

The performance of continuous solid state bioreactors having two different solid substrate flow patterns, namely plug flow and completely mixed flow, is quantified for both steady-state and transient operation using a simple mathematical model. The core assumption is that each substrate particle acts as an infinitesimal bioreactor. The residence time distribution of the particles is considered in the formulation of the equations for the mixed-flow bioreactor and the error that results from neglecting it is investigated by comparing the simulation results with those of a completely mixed, continuous bioreactor for submerged liquid fermentation (a chemostat). The model is extended to include autolysis, inter-particle inoculation and contamination. Plug flow is shown to have superior performance when high product concentration is needed, if autolysis or other undesirable late emerging phenomena occur, and when non-sterile fermentation using slow-growing microorganisms is undertaken.     

同步闪蒸汽提发酵制乙醇

为提高乙醇生产发酵强度,提出了同步汽提闪蒸乙醇发酵新过程。该过程集合了闪蒸发酵和汽提发酵的优点,在发酵的同时能更有效地在位分离乙醇,从而提高发酵强度。通过与普通发酵、闪蒸发酵、汽提发酵等过程进行间歇实验比较,同步闪蒸汽提发酵过程具有发酵强度高的优势;而且,采用耐高温酵母高温发酵、提高通气量、闪蒸罐的进料流速可进一步提高其发酵强度。该过程简单、高效,具有工业应用的潜力。     

Highly effective extraction of oil from soybean by pretreatment of solid-state fermentation with fungi

The solid-state prefermentation by Aspergillus niger (CICC 2377) and Aspergillus flavus (CICC 40536) was employed to increase the oil extraction yield from soybean. The influence of incubation time on oil yield was investigated. The maximum oil yield extracted from the substrate prefermented by Aspergillus niger for 96 h was 23%, which increased by 47.4% compared with control (15.6%). In the same fermentation conditions, the maximum oil yield extracted from substrate prefermented by Aspergillus flavus was 21.6%, which increased by 38.5% compared with control (15.6%). The quality of soybean oil was not changed obviously by the pretreatment of fermentation with fungi.     

Potential use of different agroindustrial by-products as supports for fungal ellagitannase production under solid-state fermentation

Ellagitannase is a novel enzyme responsible for biodegradation of ellagitannins and ellagic acid production. Ellagic acid is a bioactive compound with great potential in food, pharmaceutical and cosmetic industries. This work describes the ellagitannase enzyme production from partial purified ellagitannins as inducers by Aspergillus niger GH1 grown on solid-state fermentation. Solid-state fermentation was carried out on four different lignocellulosic materials (sugarcane bagasse, corn cobs, coconut husks and candelilla stalks) as matrix support and production of ellagitannase enzyme was evaluated. All lignocellulosic materials were characterized in terms of water absorption index and critical humidity point. The best lignocellulosic materials for ellagitannase production were sugarcane bagasse and corn cobs (1400 U L⁻¹ and 1200 U L⁻¹, respectively). The lowest values were obtained with candelilla stalks (500 UL-1). The highest specific productivity was obtained with corn cobs (2.5 U mg⁻¹ h⁻¹) which enable increase ellagitannase productivity up to 140 times. Corn cobs have great potential as support matrix for production of fungal ellagitannase in SSF.     

Porosity changes during packed bed solid-state fermentation

Porosity is one of the key parameters in a typical solid-state fermentation model that represents the intra and inter-particle void spaces in bioreactor bed. In this research, the particle density and moisture content of the bed were used to determine the porosity changes of the solid substrate bed during the fermentation of Aspergillus niger in a laboratory scale packed-bed bioreactor. Biomass growth was also monitored by means of measuring CO₂ and O₂ in the bioreactors outlet gas online. As such, an experimental relationship between humidity and porosity has been developed and can be used in solid-state fermentation modeling.     

Use of surface response methodology to optimize culture conditions for iturin A production by Bacillus subtilis in solid-state fermentation

Response surface methodology (RSM) was employed to optimize the cultivation conditions of Bacillus subtilis S3 for the enhancement of iturin A, a lipopeptide antibiotic used as biological pesticide, production in solid-state fermentation (SSF). The statistic experimental model predicted a maximum iturin production of 11.435 mg/g-wet solid material. Verification of the calculated maximum was done with experiments that were performed in the culture media representing the optimum combination found, and the iturin A production of 11.447 mg/g-wet solid material (average of three repeats) was obtained when B. subtilis S3 was cultivated at 25 °C for 5 days in solid fermentation containing high gluten flour 10 g and rice bran 50 g in addition to glucose 1.15%, KH₂PO₄ 1.27 mM, MgSO₄ 5.08 mM, peanut oil 1.01%, inoculum 19.49% and water content 44.97%. The iturin A production by B. subtilis S3 was increased significantly by 23%, from 9.26 mg/g-wet solid material to 11.447 mg/g-wet solid material when the strain was cultivated in the optimal medium developed by surface response methodology, as compared to medium conventionally developed by one-factor-at-a-time. The yield of iturin A (11.447 mg/g-wet solid material, with 45% moisture content) produced by B. subtilis S3 reported in this study is the highest reported to date for B. subtilis species in SSF. In addition, the use of rice bran as a substrate in solid-state fermentation for iturin A production by B. subtilis is unique.     

Temperature optimization for glycerol production by batch fermentation with Candida krusei

To maximize the final production yield and control the residual glucose at a low concentration during glycerol production by fermentation, optimal and sub‐optimal temperature control strategies were investigated. The optimal control strategy of the culture temperature was determined precisely by Pontryagin's Maximum Principle. By dividing the fermentation into multiple equal subintervals and optimizing the constant temperatures of all subintervals by a general static constrained global optimization approach, a sub‐optimal control strategy could be obtained, which was more convenient to perform in practical fermentation, whilst a similar temperature profile and final glycerol yield to those of the optimal control strategy. The experimental and simulated results showed that, compared with those at the conventional temperature of 35 °C, the final glycerol yield at the sub‐optimal temperature profile could be increased by 12–14% while the residual glucose was controlled at a value close to or less than 1% (w/v). © 2001 Society of Chemical Industry