发酵法生产葡萄糖酸钠过程中参数检测

主要研究了发酵法生产葡萄糖酸钠过程中的各参数的变化规律,通过在线监测和离线分析检测,得出各参数的变化规律:各参数的变化均与黑曲霉的生长周期有关;发酵初期(0~5 h)各参数维持恒定;发酵期(5~16 h)溶氧、残糖质量浓度分别快速降低至30%、15 g/L;酶活、葡萄糖酸钠含量快速上涨至500 U/mL、18 g/L;发酵中后期(16~20 h)维持阶段,各参数缓慢变化;发酵结束后溶氧回升。各参数的变化规律与黑曲霉生长周期的关系研究为工厂进一步优化发酵工艺、缩短发酵周期提供原始的理论依据。     

葡萄糖酸钠发酵过程中对pH细化控制的研究

在黑曲霉发酵生产葡萄糖酸钠的过程中,通过在不同发酵阶段控制不同的pH,可缩短生产周期,提高生产效率。比较5 L发酵罐中控制pH 5.0、pH 5.2、pH 5.4、pH 5.6条件下葡萄糖酸钠发酵情况,通过在线检测系统和离线数据分析,考察不同pH对降糖速率和葡萄糖氧化酶活性的影响,确定发酵前期pH控制在5.6,后期pH控制在5.2。     

ARTP诱变选育葡萄糖氧化酶高产菌株及发酵条件优化

利用常压室温等离子体诱变技术对产葡萄糖氧化酶的黑曲霉菌株进行诱变处理,通过平板筛选以及摇瓶复筛选出8株酶活较高的菌株,其中产酶活力最高的突变株为PCTC-8,酶活达到14.36 U/m L,较初始菌株的酶活提高了117.25%。然后在优化培养基的基础之上通过单因素实验对诱变菌株的发酵条件进行优化,最终确定最优的发酵条件为:接种量10%,装液量30 m L,种龄24 h,发酵时间48 h,转速225 r/min,在此条件下最高酶活可达到93.26 U/m L。     

泥炭固体发酵生产单细胞蛋白研究

对以泥炭为唯一碳源,固体发酵生产单细胞蛋白(SCP)进行了一系列的研究。选用酵母菌和黑曲霉进行混合发酵培养,考察影响单细胞蛋白生产的各个因素,如菌种接种量,培养基含水量,发酵时间,发酵温度,培养基外加氮源等。通过正交实验设计确定了优化的培养条件。即:菌种接种量为10%,培养基含水量为300%,28℃培养72 h,以蛋白胨为氮源。     

京尼平的微生物转化及其交联特性的测定分析

从土壤中富集筛选获得一株产β-葡萄糖苷酶的菌株,经菌落的形态和18S rDNA鉴定确定为黑曲霉。将筛选出的黑曲霉菌株接种于发酵培养基,利用含有京尼平苷的栀子粉作为底物发酵,通过对发酵条件优化,得到在装液量50/250 mL,栀子粉浓度为10%,转速为180 r/min,发酵时间为96 h时,京尼平的微生物转化率达到最大22%。这种微生物转化法简化了京尼平的生产工艺,大大降低了生产成本。利用微生物转化获得的京尼平交联胶原蛋白材料,研究表明其具有较好的交联特性,是一种在食品、医药等领域都具有应用前景的生物交联剂。     

槐米药渣固体发酵法生产畜禽饲料工艺的研究

以发酵酶解液中总糖、芦丁、槲皮素含量为实验分析指标来确定槐米残渣固体发酵生产畜禽饲料生产工艺。实验结果表明:黑曲霉槐米残渣固体发酵的最佳工艺条件为接种量4%,发酵酶解p H 5.5,温度35℃,时间5 d。槐米残渣经发酵酶解的总糖量高于未经发酵酶解的总糖量60%以上,槲皮素含量高于65%以上。槐米残渣经黑曲霉发酵酶解可作为抗菌、消炎畜牧营养饲料。     

黑曲霉DB056产柚苷酶发酵条件初步优化

以α-鼠李糖苷酶活力和柚苷酶活力为考察指标, 研究了发酵条件对黑曲霉DB056产柚苷酶的影响。结果表明: 发酵温度、菌丝形态、培养基初始pH、接种量和装液量对黑曲霉DB056产柚苷酶都具有重要影响。初步优化得到黑曲霉DB056产柚苷酶的条件为: 培养基初始pH 8.0, 玻璃珠添加个数5个, 装液量45 mL, 接种量7%, 发酵温度34°C, 摇床转速190 r/min。采用此条件进行发酵, 高效液相色谱法检测α-鼠李糖苷酶活力最大可达1076.32 U/mL, 柚苷酶活力最大可达420.68 U/mL, 分别比初始条件提高了72.35%和78.03%。黑曲霉DB056不仅在对数生长期能快速合成柚苷酶, 在稳定期及衰亡期也会不断地分泌柚苷酶。阐明了发酵条件对黑曲霉DB056产柚苷酶的影响并获得了经过初步优化的发酵条件, 为进一步优化发酵条件, 提高黑曲霉DB056产柚苷酶的产量奠定了良好的基础。     

酶制剂在大曲丢糟再发酵中的应用

目的:在添加糖化酶和纤维素酶的条件下,采用黑曲霉与假丝酵母发酵丢糟生产单细胞蛋白饲料.方法:采用L(34)水平正交试验对糖化酶与纤维素酶的添加量、黑曲霉与假丝酵母的比例、发酵时间进行了探讨.结果:单细胞蛋白饲料生产的最佳生产工艺条件为:糖化酶的添加量为0.03%、纤维素酶的添加量为1.5%、黑曲霉:假丝酵母=1:3、培养时间为8d,产品粗蛋白含量可达38.72%.结论:酶制剂的添加对丢糟转化为单细胞蛋白饲料具有明显的促进作用.     

N+注入和60Co-γ辐照对柠檬酸发酵菌黑曲霉的诱变效应

首次尝试了应用两种核技术手段(同时)对黑曲霉进行诱变,即将大剂量^60Co-γ辐照的黑曲霉孢于直接进行低能氮离子注入,使处于休眠状态下的黑曲霉抱子同时受至^60Co-γ辐照和N^ 注入的作用。通过溴甲酚绿指示性平板辅助筛选和摇瓶发酵。获得了1株产酸提高18．44％、转化率达1034．5％的M3代菌株CN05,为柠檬酸发酵菌黑曲霉的进一步育种工作提供了诱变参数和高产出发菌株。     

黑曲霉与里氏木霉固态混合发酵产β-葡萄糖苷酶

对黑曲霉NL02与里氏木霉RUT-C30固态混合发酵产β-葡萄糖苷酶的发酵培养基进行优化,研究培养基含水率、C源、N源、接种量、温度和2种菌种不同延长接种时间与接种比例对β-葡萄糖苷酶活力的影响。研究表明：麸皮17.5 g、玉米芯7.5 g、（NH4）2SO4 0.40 g、尿素0.37 g、黑曲霉孢子接入量为107个接种到250 mL三角瓶中,温度30 ℃、摇床转速100 r/min时,里氏木霉以105个孢子与黑曲霉同时接入,每克干曲所得β-葡萄糖苷酶的活力为132.45 IU,较黑曲霉单独培养时的104.35 IU提高了26.94%。     

Oxygen-enriched fermentation of sodium gluconate by Aspergillus niger and its impact on intracellular metabolic flux distributions

Bioprocess and Biosystems Engineering - Different concentrations of oxygen-enriched air were utilized for sodium gluconate (SG) fermentation by Aspergillus niger. The fermentation time shortened...     

Kinetic analysis of sodium gluconate production by Aspergillus niger with different inlet oxygen concentrations

Bioprocess and Biosystems Engineering - To further understand fermentation kinetics of sodium gluconate (SG) production by Aspergillus niger with different inlet oxygen concentrations, logistic...     

Comparative analysis of calcium gluconate and sodium gluconate techniques for the production of gluconic acid by Aspergillus niger

Sodium gluconate and calcium gluconate methods are important techniques available for gluconic acid fermentation. The comparative analysis of these fermentations has been addressed using Aspergillus niger. The techniques are equally influenced by the spores age in slant growth, inoculum level in germination and production media, different levels of Fe, Cu, Zn and Mn. Sodium gluconate method is promising with respect to lesser time for slant age (3 d) and lesser time of fermentation (6 d) compared to the calcium gluconate method (slant age — 6 d, and time of fermentation — 7 d).     

Optimisation of fermentation conditions for gluconic acid production by a mutant of Aspergillus niger

Aspergillus niger ORS-4, isolated from the sugarcane industry waste materials was found to produce notable level of gluconic acid. From this strain, a mutant Aspergillus niger ORS-4.410 having remarkable increase in gluconic acid production was isolated and compared for fermentation properties. Among the various substrates used, glucose resulted into maximum production of gluconic acid (78.04 g/L). 12% concentration led to maximum production. Effect of spore age and inoculum level on fermentation indicated an inoculum level of 2% of the 4-7 days old spores were best suited for gluconic acid production. Maximum gluconate production could be achieved after 10-12 days of the fermentation at 30 degrees C and at a pH of 5.5. Kinetic analysis of production indicated that growth of the mutant was favoured during initial stages of the fermentation (4-8 days) and production increased during the subsequent 8-12 days of the fermentation. CaCO3 and varying concentrations of different nutrients affected the production of gluconic acid. Analysis of variance for the factors evaluated the significant difference in the production levels.     

黑曲霉纤维素酶突变子T-DNA插入位点的遗传分析及性质鉴定

采用羧甲基纤维素钠筛选培养基,对黑曲霉(Aspergillus niger)T-DNA突变子文库进行筛选,分离到一株纤维素酶分泌水平较低的菌株AN-108,为野生型菌株的83.3%。进一步测定该突变子固体发酵的纤维素酶活力,与野生型菌株相比没有明显差别,推测与固体发酵培养基中含有的天然糖类有关。在添加不同糖类的CMC-Na平板上培养该突变子,菌落周围均出现较明显的水解圈,结果显示糖类可能作为诱导物克服突变带来的影响。为了确定突变子AN-108中何种基因被阻断,采用反向PCR方法分析了T-DNA插入位点的序列,获得序列经过比对分析发现,该序列与黑曲霉An14g03730同源程度达90%,编码富含脯氨酸蛋白(proline-rich protein,PRP)。     

甜菜渣发酵制备蛋白饲料的研究

以甜菜渣为原料,对固态发酵制备菌体蛋白饲料进行了研究。将纤维素酶水解法替代常规的黑曲霉发酵法进行原料的预处理,其最适酶解条件为:纤维素酶添加量为25 u.g-1,酶解时间为16 h。以面包酵母B188和产朊假丝酵母B204为菌种进行混合发酵,在最适发酵条件下,50 h粗白质质量分数达到21%,蛋白质净增量为14%。     

Production of calcium gluconate by fermentation.

Calcium gluconate production by Aspergillus niger was investigated in shake flask, rolling shaker, air-lift reactor and stirred reactor. Growth pattern of the organism and fermentation conditions determined the yield of the product. High calcium gluconate production was achieved in air-lift reactor with pellet form of cell growth at moderate specific growth rate and biomass concentration. In another variation of air-lift reactor, when calcium carbonate was confined to a cellulose membrane, calcium gluconate production was maximum (149 g/L). At higher specific growth rate, obtained in shake flask, despite the formation of cell pellets, product formation was low. Physical separation of particulate calcium carbonate and growing cells favoured product formation. In stirred reactor pulpy mycelial growth was obtained and calcium gluconate production was poor.     

Sodium gluconate production byAspergillus niger with intermittent broth replacement

Intermittent broth replacement was carried out to enhance the productivity and purity of sodium gluconate usingAspergillus niger by reducing the concentration of unmetabolized glucose. As inoculum size increased, length of lag phase was shortened and high initial production rate of sodium gluconate was achieved. However, too high inoculum concentration lowered productivity during the later stage of fermentation and increased residual glucose at the end of cultivation. When culture broth was replaced intermittently with distilled water, fresh medium, or recycled medium for comparison with traditional fermentation method, production of sodium gluconate was enhanced more than 1.5 fold and active production period could be prolonged without residual glucose. In addition, productivity was maintained at a level higher than 6 g/L/nr. Therefore, it was found that the reduction of biomass and viscosity by intermittent broth replacement could enhance the productivity.