乙醇对米曲霉发酵产曲酸的影响

以从湖南冰糖橙皮上筛选到的优良产曲酸菌种米曲霉为研究对象,研究乙醇对生成曲酸的影响。结果表明,在添加质量分数10%的乙醇条件下,当葡萄糖含量为6%时,发酵5 d,曲酸产量提高到43.80 g/L,比未添加乙醇的曲酸得率(15.68 g/L)提高179.34%。其作用机理是乙醇增加了菌株与发酵液的比接触面积,降低了发酵液的粘稠度,使传质、传氧系数增大,葡萄糖转化为曲酸的转化率提高。在米曲霉发酵产曲酸的培养基中添加乙醇,能有效提高曲酸产量和生产效率。     

米曲霉形态与曲酸生产的关系

以米曲霉为出发菌株生产曲酸,通过改变培养基浓度和孢子接种量来研究曲酸生产关键因素对A.oryzae菌体形态的影响,进一步通过不同形态菌体发酵分析菌体形态与曲酸生产的关系。培养基中的碳氮比对A.oryzae菌球的直径的大小具有较大影响。当孢子浓度为109个/m L时,A.oryzae主要呈菌丝形态;但当孢子浓度为107~108个/m L时,菌体形态呈现为球状,并随着孢子浓度的增大菌球直径减少。A.oryzae发酵生产曲酸的最佳形态为菌球,并且菌球直径与曲酸合成能力关系密切,菌球直径为0.25~0.35 mm时,单位细胞曲酸积累量最高。     

曲酸生产菌种的分离筛选与发酵条件研究

从土壤中分离出一株曲酸产量较高的米曲霉(Aspergillusoryzan)菌株,对该菌株的发酵条件进行了初步研究。结果表明,该菌株在淀粉8%、酵母膏0.2%、MgSO4·7H2O0.05%、K2HPO40.1%、pH6.0的培养基中,28℃恒温摇床振荡培养6d,摇瓶发酵液曲酸含量为41.2mg/mL。     

曲酸生产菌种的分离筛选与发酵条件研究

从土壤中分离出一株曲酸产量较高的米曲霉(Aspergillusoryzan)菌株,对该菌株的发酵条件进行了初步研究。结果表明,该菌株在淀粉8%、酵母膏0.2%、MgSO4·7H2O0.05%、K2HPO40.1%、pH6.0的培养基中,28℃恒温摇床振荡培养6d,摇瓶发酵液曲酸含量为41.2mg/mL。      

米曲霉C491果胶酶的固定化研究

比较了不同载体对米曲霉Ｃ－４９１果胶酶固定化的效果,表明聚乙烯醇水凝胶法可较好地固定果胶酶,选择聚乙烯醇浓度１２％,固定化时间１２ｈ,用酶量３８．５Ｕ／ｇ载体,可使酶活力回收达到６７．３％。     

曲酸生产菌种的筛选和发酵工艺条件的优化

通过多次UV诱变米曲霉（Aspergillus oryzae）QA96．8，获得高产曲酸生产菌株QA97．14。该菌株的适宜发酵条件为温度30℃，葡萄糖10％，淀粉水解液10％，酵母浸出物0．5％，KH2PO4 0．1％，MgSO4 0．05％。在此条件下摇瓶培养8d，产酸量由原来的4．79g／L上升到18．13g／L。     

米曲霉固体发酵生产果胶酶的研究

以鼓皮和桔皮粉为主要原料，采用米曲霉（As－pergillusoryzae）诱变菌株C－491进行固体发酵培养，培养物最高果胶酶活力可达到1694．8u／g鲜曲。产酶最适培养基为：麸皮100g，桔皮粉50g，硫酸铵1.5g，料水比1：0．9。最佳培养条件为35C培养60h。成曲的最佳浸提条件为：以蒸馏水为浸提剂，蒸馏水与鲜曲用量之比为10：1（v／w），在4C下振荡浸提2h。     

复合诱变对米曲霉2336产酸量的影响

以米曲霉(Aspergillus oryzae)2336为出发菌株,经紫外线、60Co复合诱变处理,采用快速筛选法获得不产黄曲霉毒素的曲酸高产菌株UC690,以玉米淀粉为碳源,发酵7d,曲酸产量由原来的12.34g/L提高到50.47g/L。经遗传稳定性试验,这一变异菌株可应用于工业化生产。     

利用豆渣、黄浆水发酵生产曲酸的研究

实验以豆腐渣、黄浆水为主要原料利用米曲霉发酵生产曲酸,对发酵生成曲酸所需添加的各种营养因素和发酵条件进行了研究。得出该茵利用豆渣的最佳发酵培养基为:豆渣80％、麸皮24％、酵母膏1.2％、Mg-SO4·7H2O 0.16％,pH为自然;接种量为10％,每250mL三角瓶装量为50g,在30℃发酵培养,5～6d菌体生长量和曲酸产量最大。米曲霉利用黄浆水生产曲酸的最佳发酵培养基为:葡萄糖12％、酵母膏0.5％、MgSO4·7H2O0.05％、K2HPO4 0.05％、黄浆水100％,pH为6.0,接种量10％。每250mL三角瓶装量100mL在30℃转速为200r/min的摇床振荡发酵培养,5～6d菌体生长量和曲酸产量最大。     

Production of Citric Acid from Beet Molasses by Immobilized Cells of Aspergillus niger

Citric acid was produced from beet molasses by immobilized cells in shake flasks and glass bioreactor. Maximum concentration of citric acid (35 g/L) was observed from immobilized A. niger cells in shake flasks after 28 days fermentation. In repeated batch fermentations, the A. niger cells entrapped in Ca-alginate gel beads retained ability to produce citric acid for up to 84 days.     

甘蔗废蜜澄清技术的研究

对甘蔗废蜜的澄清处理进行了研究.通过实验得到在稀释度1;6,磷酸量450ppm,pH值7.0,聚丙烯酰胺4ppm,75℃恒温水浴中30min的条件下效果最佳.     

固定化活酵母连续发酵生产糖蜜酒精

固定化活酵母技术，在广西平南糖厂酒精生产中使用，已取得了高收回和低消耗的效果。主要介绍了该技术的优点和使用该技术应注意的事项，并给出了所采用的双浓度流加连续发酵的工艺流程图。     

废糖蜜制液体糖初探

本文对云南的甘蔗糖厂废糖蜜用水稀释至４０°Ｂｘ，加磷酸预处理，用酒精除胶体，回收酒精后，再用离子交换树脂脱灰，活性炭脱色，脱苦味，制得液体糖，作了较详细的论述。     

甘蔗废蜜澄清处理对糖分影响的研究

甘蔗废蜜的澄清对于发酵以及糖分回收具有重要意义,也是糖业需要解决的一个问题.本文对甘蔗废蜜澄清处理中pH值、絮凝剂量、温度对糖分的影响进行了研究,并通过正交实验选取最佳反应条件为pH值7.0,絮凝剂量4 ppm,温度85℃.     

米曲霉大米发酵提取物抗氧化活性的比较研究

用米曲霉发酵后的大米,其提取物是一种非常有效的天然抗氧化剂,具有清除自由基,金属螯合的效果.提取物中含有多种成分,其中最具有生物活性的成分是酚类物质.本文通过测定大米发酵过程中的淀粉酶、纤维素酶、β-葡萄糖苷酶三种酶的活性和自由基清除能力、还原能力、金属螯合能力、总酚含量,比较购于日本的Aspergillus oryzae M-1、Aspergillus oryzae MC-01、Aspergillus oryzae SP-01、Aspergillus soji.最后选取其发酵提取物总酚含量9.60 mg/g的Aspergillus soji用于进一步实验.     

Separation of Sucrose and Reducing Sugar in Cane Molasses by Nanofiltration

Recovery of sugars from cane molasses is a promising approach to increase the added value of molasses and reduce its environmental pollution. In this work, for the first time, nanofiltration (NF) was used for the separation of sucrose and reducing sugar in cane molasses by a cascade diafiltration-concentration process. The retention difference between sucrose and reducing sugar by all the tested NF membranes was not distinct at 25 °C, while due to the thermal-induced pore size change and enhanced solute diffusivity, the NF retention behavior changed significantly at 60 °C, and the DL membrane with a sucrose retention of 96% and a reducing sugar retention 5% was selected for the process optimization and modeling. High temperature (55–60 °C), low permeate flux (below 15 Lm^?2 h^?1), and high sugar concentration resulted in a low retention of reducing sugar due to the dominant diffusive mass transfer, which was desirable for the molasses separation by NF. Mathematical modeling could well predict the diafiltration and concentration processes if using right sugar retention data. The deviations between prediction lines and experimental data in the cross-flow filtration of real solution were mainly caused by the permeate flux variation rather than membrane fouling. After diafiltration, the ratio of sucrose in total molasses sugar increased from 76.1 to 87.9%, while in the permeate of the second concentration step, the ratio of sucrose was only 2.4%. Thus, the retentate of diafiltration could be directly used for sucrose crystallization to avoid the accumulation of reducing sugar and salts, and the permeate of the second concentration step could be concentrated by NF270 at room temperature to produce syrup drinking.