复合式厌氧折流板反应器作为制氢系统的乙醇型发酵调控研究

乙醇型发酵被认为是产氢发酵类型中的最佳选择.以赤糖废水为底物,进行了五格室、总有效容积为43.2 L的复合式厌氧折流板反应器作为制氢系统的乙醇型发酵调控研究.为期64 d、3个阶段的实验结果表明,以好氧活性污泥作为接种污泥,在水力停留时间为12 h、进水pH为5.0~7.0之间、温度为35℃±1℃的条件下,通过分阶段提高进水COD的方式,可使HABR系统在启动阶段培育出具有稳定产氢效能的乙醇型发酵菌群体系.由于废水进入每一个格室的状态不同,每个格室形成的微生物菌群结构不同,虽然也都形成了乙醇型发酵,但是产氢能力有所差异,第二格室产氢量最高.系统第二阶段,COD为6500 mg·L-1时,平均COD去除率为43.34%,平均产氢量为14.91 L·d-1,此阶段效果最佳.在第三阶段,COD过高,系统产氢量与COD去除率出现下降,但产氢系统并没有崩溃.系统可同时生产氢和乙醇,其能量值在第二阶段达到最高值,平均为3340.62 kJ·d-1.在不同的COD条件下,氢气与乙醇生产速率的线性关系为y(氢)=0.351x(乙醇)-0.181(R2=0.9767).     

不同陈化烟叶叶面高温微生物多样性

以国内外不同品种、不同陈化时间的10个烟叶样品为材料,对其叶面高温微生物进行了分离纯化、鉴定和多样性研究,以了解表面高温微生物在烟叶陈化发酵中的作用.结果表明:陈化烟叶表面高温菌总量为103~105个/g,高温细菌占绝对优势,真菌很少,未能分离到放线菌和酵母菌;高温细菌主要包括芽孢杆菌属(Bacillus)和地芽孢杆菌属(Geobacillus)两个属,芽孢杆菌属为优势菌属;高温霉菌主要包括青霉属(Penicillium)和曲霉属(Aspergillus),曲霉属为优势菌属.国内外烟叶表面微生物种类和数量有所差异,与陈化时间和烟叶品种等因素有着密切关系.     

顺丁烯二酸异构酶工程菌发酵条件优化

为提高重组大肠杆菌中顺丁烯二酸异构酶表达量,通过正交试验设计,对工程菌的生长条件和目的蛋白可溶表达条件进行优化.采用250 mL三角瓶中装有50 mL(Amp 100 mg L-1)的培养基,分别研究培养基中葡萄糖、蛋白胨、酵母浸粉的浓度,培养基pH值以及摇床转速、装液量、接种量等对蛋白可溶表达量的影响.确定顺丁烯二酸异构酶工程菌最优化培养基为:蛋白胨20 g L-1、酵母浸粉2.5 g L-1、K2HPO4·3H2O 3.0 g L-1、KH2PO4 1.5 g L-1、NaCl 6 g L-1、MgSO43 g L-1,培养基pH调至6.5.确定顺丁烯二酸异构酶工程菌可溶性表达最优条件为:37℃下培养至D600 nm值为1.0时,添加终浓度为0.05 mmol L-1的IPTG进行诱导,诱导温度37℃,摇床转速220 r min-1,装液量20%,接种量5%,诱导时长为6 h.利用BioFlo 415发酵罐以最优化的培养基和发酵条件对该工程菌进行了3批发酵实验,与摇瓶实验相比,顺丁烯二酸异构酶的表达量提高了近1.5倍,单位发酵液的酶活力由46 U mL-1发酵液提高到78 U mL-1发酵液.以上数据为顺丁烯二酸异构酶重组工程菌的中试发酵奠定了基础.图7表2参17     

Evaluating the impact of sulfamethoxazole on hydrogen production during dark anaerobic sludge fermentation

● SMX promotes hydrogen production from dark anaerobic sludge fermentation. ● SMX significantly enhances the hydrolysis and acidification processes. ● SMX suppresses the methanogenesis process in order to reduce hydrogen consumption. ● SMX enhances the relative abundance of hydrogen-VFAs producers. ● SMX brings possible environmental risks due to the enrichment of ARGs. The impact of antibiotics on the environmental protection and sludge treatment fields has been widely studied. The recovery of hydrogen from waste activated sludge (WAS) has become an issue of great interest. Nevertheless, few studies have focused on the impact of antibiotics present in WAS on hydrogen production during dark anaerobic fermentation. To explore the mechanisms, sulfamethoxazole (SMX) was chosen as a representative antibiotic to evaluate how SMX influenced hydrogen production during dark anaerobic fermentation of WAS. The results demonstrated SMX promoted hydrogen production. With increasing additions of SMX from 0 to 500 mg/kg TSS, the cumulative hydrogen production elevated from 8.07 ± 0.37 to 11.89 ± 0.19 mL/g VSS. A modified Gompertz model further verified that both the maximum potential of hydrogen production (P_m) and the maximum rate of hydrogen production (R_m) were promoted. SMX did not affected sludge solubilization, but promoted hydrolysis and acidification processes to produce more hydrogen. Moreover, the methanogenesis process was inhibited so that hydrogen consumption was reduced. Microbial community analysis further demonstrated that the introduction of SMX improved the abundance of hydrolysis bacteria and hydrogen-volatile fatty acids (VFAs) producers. SMX synergistically influenced hydrolysis, acidification and acetogenesis to facilitate the hydrogen production.     

荧光原位杂交技术解析发酵产氢细菌群落结构

应用荧光原位杂交(FISH)技术,研究了连续流搅拌槽式(CSTR)发酵制氢反应器中2种产氢发酵类型的菌群组成和发酵类型转化过程中的菌群种类和数量变化及其对产氢速率、生物量和发酵产物的影响.结果表明,梭菌属和肠杆菌科在决定产氢发酵类型方面有重要作用.以梭菌为优势种群的乙醇型发酵比以肠杆菌为优势种群的丁酸型发酵具有更佳的产氢能力.实验结果能够与生物发酵系统常规监测指标形成很好的印证.     

一株运动发酵单胞菌Zy-1快速生产乙醇

经多次实验优化，得到运动发酵单胞菌Zy发酵葡萄糖生产乙醇较合适的条件．Zy的诱变菌株Zy-1在该条件下发酵葡萄糖生产乙醇比原始菌株更有较大优势．当葡萄糖浓度为200gL^-1时，发酵48h，乙醇浓度96．5gL^-1，残糖2．3gL^-1，发酵效率为94．42％．Zy-1发酵天然原料米粉、木薯、红薯干等，发酵时间44h，乙醇浓度达95gL^-1以上，发酵效率92％以上．发酵液用DNS法测定，还原糖约2gL^-1，残总糖因原料种类不同，其值有所差异（5～20gL^-1）．经薄层层析分析，发酵液无葡萄糖，而是二糖、三糖等低聚糖．图2表5参12     

猪粪和羊粪与麦秆不同配比中温厌氧发酵研究

研究了猪粪和羊粪分别与麦秆不同配比中温(35℃)厌氧发酵对产气量、消化时间和最优C/N值的影响。结果表明,猪粪与麦秆在中温厌氧发酵时,所需的最优C/N值为21,且经141 d就可充分发酵,最大干物质累积产气量可达369.53 mL/g。羊粪与麦秆中温厌氧发酵时,所需的最优C/N值为24,且经96 d就可充分发酵,最大干物质累积产气量可达209 mL/g。猪粪秸秆中温厌氧发酵时易发生酸化,发酵前应通过预处理来减少酸化可能;而羊粪麦秆不易发生酸化。     

污泥性质对污泥水解酸化效果的影响

采用3组构造一致的完全混合流态水解酸化反应器,分别以同等浓度的絮凝污泥、初沉污泥和剩余污泥作为底物污泥,在温度35℃,初始p H=10的反应条件下,研究污泥性质的差异对污泥水解酸化产物及产率的影响。实验结果表明:与初沉污泥、剩余污泥相比,絮凝污泥更易水解产酸发酵,至第9天水解产SCOD达到最大值2 713.2 mg/L,第7天酸化产VFAs达到峰值1 392.7 mg/L。3种污泥酸化产VFAs的主要组分均为乙酸和丙酸,但絮凝污泥VFAs组分中乙酸、丙酸这种优势更加明显,其所占比例分别高达48.9%和27.2%。此外,3种污泥水解酸化产碳源的同时均伴随着氮、磷元素的释放,整体而言,絮凝污泥产酸发酵中氮、磷元素的释放量及释放率均较低。     

Microbial safety control of compost material with cow dung by heat treatment

Various kinds of pathogenic bacteria derived from the intestinal tract of animals exist in compost material like cow dung.In order to sterilize the pathogenic bacteria completely in compost material,the cow dung was put into a heat treatment machine in pilot plan, and harmless condition in short time was examined.The results indicated,pathogenic indicator bacteria such as coliform bacteria, fecal coliform,Escherichia coli and salmonella were all 10~6 cfu/g dw at the beginning,died rapidly when cow dung temperature rose to above 50℃,and not detected at 54-68℃for 6-24 h heat treatment.Coliform bacteria and salmonella in heated cow dung were not detected by re-growth culture and enrichment culture examination.Moreover,it was hardly influenced on the fermentation ability of composting microbe,organic decomposition bacteria.During heat treatment,the mesophile decreased rapidly and the thermophile stabilized or increased,and the most of composting microbe were bacillus in cow dung by fluorescence microscope,this indicated that bacillus was dominator and composting microbe in composting process.     

利用城市污泥生产苏云金杆菌生物农药

用城市污水污泥和经酸水解后的城市污泥作为培养基发酵苏云金杆菌Bacillusthringiensis(B.t),与常规的黄豆粉培养基作比较.检测B.t发酵液的pH值变化,总细胞数及活孢子数以及在发酵48h后,用2龄家蚕作试虫比较3种发酵液的生物毒性.结果表明,用污泥培养的B.t总细胞数及活孢子数略低于黄豆粉培养基生产的B.t,但两者的细菌总数都在同一数量级,差别不显著.用污泥培养B.t,芽孢大量形成109个/mL的时间,比用黄豆粉培养基生产的B.t约提前10h,发酵周期明显缩短.生物毒性实验表明用污泥培养的B.t孢晶混合液比用黄豆粉生产的B.t孢晶混合液毒性高,在相同的稀释倍数下,家蚕的死亡率提高了10%,酸水解污泥毒性略差.