酒色着色菌利用产酸克雷伯氏菌发酵废液产氢

研究了酒色着色菌(Chromatium vinosum DSM185)利用产酸克雷伯氏菌（Klebsiella oxytoca HP1）发酵产氢废液进行光发酵和暗发酵产氢的可行性,以达到对产氢底物的充分利用和对产氢废液的进一步处理。研究结果表明C.vinosum可以利用K.oxytoca的发酵废液进行光发酵产氢和暗发酵产氢。C.vinosum发酵产氢后废液中残余还原糖和主要有机酸（丁酸）的含量明显降低,发酵产氢的最佳pH为6.5,添加0.1%(W/W)NH₄Cl能促进产氢。在光照条件下丁酸利用率可达54.38%,产氢量达36.97 mL/mg;在黑暗条件下丁酸利用率可达36.01%,产氢量达37.50mL/mg。     

深红红螺菌吸氢酶缺失突变株在管式光合反应器中的产氢

本研究设计了一种2 L分体式管式光合反应器, 并研究了深红红螺菌(Rhodospirillum rubrum)吸氢酶缺失突变株在该反应器中分别利用人工光源(持续光照与光暗交替)和自然光的产氢规律。结果表明在人工光照条件下R. rubrum的产氢可维持5 d, 持续光照和光暗交替条件下(12 h: 12 h)的氢产量可分别达到5752 mL/PBR ± 158 mL/PBR和5012 mL/PBR ± 202 mL/PBR; 自然光条件下, 最适产氢光照强度为30000 Lux~40000 Lux; 在此光照条件下, R. rubrum产氢可维持6 d~ 10 d, 最高氢产量可达到2800 mL/PBR。尽管利用自然光的氢产量比利用人工光源氢产量低, 但是利用自然光的产氢比较经济, 并且该光合产氢系统操作简单, 该工艺有望开发为低成本的光合细菌产氢技术。     

木糖发酵产氢菌的筛选及其生长产氢特性研究

利用改进的Hungate厌氧技术, 从牛粪堆肥中分离出一株能有效利用木糖发酵产氢的中温菌HR-1。通过16S rRNA系统发育树分析表明, 菌株 HR-1 与丙酮丁醇梭菌Clostridium acetobutylicum ATCC 824 相似性最高为96%, 结合生理生化和生长特性分析表明, HR-1是梭菌属Clostridium的一个新种, 命名为Clostridium sp. HR-1。菌株HR-1为单胞生长的规则杆状菌(0.3 mm ~0.6 mm)×(1.4 mm~2.3 mm), 革兰氏染色为阴性, 无荚膜、无鞭毛、表面光滑、无明显凸起, 专性厌氧菌。HR-1可在10°C~45°C, pH 4.0~10.0条件下生长; 37°C和pH 8.0分别为其最适生长条件。发酵PYG的主要发酵产物有氢气、二氧化碳、乙酸、丁酸及少量乙醇。HR-1可以利用有机氮源和无机氮源生长并产氢, 酵母提取物是其最佳产氢氮源。HR-1在木糖浓度为3 g/L和初始pH 6.5条件下, 其比产氢量为1.84 mol-H2/mol-木糖, 最大比产氢速率为10.52 mmol H2/h·g-细胞干重。HR-1可以亦利用葡萄糖、半乳糖、纤维二糖、甘露糖和果糖等碳源生长并发酵产氢, 发酵葡萄糖时比产氢量为2.36 mol-H2/mol-葡萄糖。     

响应面法优化Vc二步发酵新菌系产2-酮基-L-古龙酸的培养基

以短小芽胞杆菌(Bacillus pumilus)HJ-04作为维生素C二步发酵第2步中的伴生菌,促进产酸菌产维生素C(Vitamin C,Vc)前体2-酮基-L-古龙酸(2-keto-L-gulonic acid,2-KGA)的能力强于工业生产用菌株巨大芽胞杆菌(Bacillus megaterium) B2980.采用单因素试验、Plackett-Burman(PB)试验及Box-Behnken试验对影响新菌系发酵产2-KGA的6个因素进行分析优化.结果表明,L-山梨糖、尿素、玉米浆为显著影响因子.最佳产酸条件为L-山梨糖94.95 g/L,尿素11.99 g/L,玉米浆14.13g/L.优化后产酸量提高12.31 mg/mL,产酸周期缩短6h.     

高效产氢菌株Enterococcus sp. LG1的分离及产氢特性

采用Hungate厌氧培养技术分别从厌氧污泥、好氧污泥及河底泥中分离出12株厌氧产氢细菌,并对其中的Enterococcus sp.LG1(注册号:EU258743)进行了研究.结果表明,该株细菌为专性厌氧菌,经革兰氏染色结果为阴性.通过16S rDNA碱基测序和比对证实,该菌株是目前尚未报道过的1个新菌种,初步确定其细菌学上的分类地位.同时,以灭菌预处理的污泥为底物培养基,对该菌的产氢能力及污泥发酵过程中底物性质变化(SCOD、可溶性蛋白质、总糖和pH值等)进行了探讨.实验结果显示,产氢茵Enterococcus sp.LG1的发酵过程中只有H2和CO2产生,无CH4产生.产气量最高为36.48 mL/g TCOD,氢气含量高达73.5%,为已报道文献中以污泥为底物发酵制氢中之最高.根据污泥发酵产物分析得知,该菌的发酵类行为典型的丁酸型发酵.     

种泥预处理和发酵温度对暗发酵产氢的影响研究进展

生物质暗发酵产氢不仅可以处理有机废物,同时可以获得清洁能源,实现了废物资源化利用。然而产氢种泥中大量耗氢菌的存在会导致暗发酵氢气产量低等问题,因此种泥预处理是暗发酵产氢的必需条件。随着暗发酵产氢基质的多样化,产氢种泥的预处理方法也不断发展。对近十年来产氢种泥预处理方法的发展进行了综述,并且结合发酵温度,讨论了种泥预处理方法和发酵温度两方面条件对暗发酵产氢的影响,并对该研究方向提出了展望,以期为后续暗发酵产氢的进一步研究提供参考。     

产Epothilone B纤维堆囊菌的选育与发酵优化

目的:获得高产Epothilone B菌株和最佳营养条件及发酵条件。方法:采用紫外线照射的方法对实验室保存的1株纤纤堆囊菌AHB125进行诱变处理,并采用单因素和正交实验优化培养基中的碳源、氮源和发酵条件。结果:经诱变后获得1株遗传性能稳定变异菌株(SC4-56),Epothilone B产量为14.6mg/L,比初始菌株高195%;该菌株最佳碳源和氮源为6%玉米淀粉和3%蛋白胨,产量分别为20.5和21.8 mg/L;最佳发酵条件为:转速160r/min,温度32℃,接种量8%(V/V),装液量90 mL/500mL,优化后经验证实验,Epothilone B达28.24 mg/L。结论:获得了1株高产量变异菌株,并确定了最佳生产条件。     

种泥预处理和发酵温度对暗发酵产氢的影响研究进展

生物质暗发酵产氢不仅可以处理有机废物,同时可以获得清洁能源,实现了废物资源化利用。然而产氢种泥中大量耗氢菌的存在会导致暗发酵氢气产量低等问题,因此种泥预处理是暗发酵产氢的必需条件。随着暗发酵产氢基质的多样化,产氢种泥的预处理方法也不断发展。本文对近十年来产氢种泥预处理方法的发展进行了综述,并且结合发酵温度,讨论了种泥预处理方法和发酵温度两方面条件对暗发酵产氢的影响,并对该研究方向提出了展望,以期为后续暗发酵产氢的进一步研究提供参考。     

产青霉素酶枯草芽孢杆菌发酵条件的优化

目的:对一株产青霉素酶的重组枯草芽孢杆菌(Bacillus subtilis DB104/pWB-pemp)的摇瓶发酵条件进行优化.方法:利用单因素实验及正交实验等方法考查重组菌摇瓶发酵条件,研究不同浓度的碳源、氮源、金属离子、磷酸盐及不同pH、接种量、装液量和温度等条件对产青霉素酶的影响.结果:重组菌株摇瓶最适发酵条件为pH 7.0、接种量3％、装液量14％、发酵温度37℃,培养基成分为2％蔗糖、3.5％酵母膏、0.1mmol/L镁离子、0.4％磷酸盐.结论:最优条件下,发酵36h,产酶活力达到2227.8U/mL,为先前研究结果(1 580 U/mL)的1.41倍,为重组菌的大规模发酵生产奠定了基础.     

产弹性蛋白酶菌种的筛选及发酵条件优化研究

从合肥肉联厂附近的土壤和污水中分离得到19株产弹性蛋白酶菌株,初步鉴定该菌株属于假单胞菌属.经过发酵复筛有三株产酶能力超过15u/mL.实验对菌株最佳产酶发酵条件进行了优化2%干酪素、0.5%葡萄糖、0.4%酵母膏、0.2% K2HPO4、0.01% MgSO4·7H2O;起始pH值7.0;最适发酵温度为30℃;装液量为25mL/250mL;该菌株在28h左右产弹性蛋白酶的量达18u/mL.     

Hydrogen production conditions from food waste by dark fermentation with Clostridium beijerinckii KCTC 1785

The optimum conditions for biological hydrogen production from food waste by Clostridium beijerinckii KCTC 1875 were investigated. The optimum initial pH and fermentation temperature were 7.0 and 40°C, respectively. When the pH of fermentation was controlled to 5.5, a maximum amount of hydrogen could be obtained. Under these conditions, about 2,737 mL of hydrogen was produced from 50 g COD/L of food waste for 24 h, and the hydrogen content in the biogas was 38%. Hydrogen production rate and yield were about 108 mL/L·h and 128 mL/g COD_degraded, respectively. High concentrations of acetic (< 5,000 mg/L) or butyric acid (< 3,000 mg/L) significantly inhibited hydrogen production.     

A novel isolate of <Emphasis Type="Italic">Clostridium butyricum</Emphasis> for efficient butyric acid production by xylose fermentation

Bacterial fermentation of lignocellulose has been regarded as a sustainable approach to butyric acid production. However, the yield of butyric acid is hindered by the conversion efficiency of hydrolysate xylose. A mesophilic alkaline-tolerant strain designated as Clostridium butyricum B10 was isolated by xylose fermentation with acetic and butyric acids as the principal liquid products. To enhance butyric acid production, performance of the strain in batch fermentation was evaluated with various temperatures (20–47 °C), initial pH (5.0–10.0), and xylose concentration (6–20 g/L). The results showed that the optimal temperature, initial pH, and xylose concentration for butyric acid production were 37 °C, 9.0, and 8.00 g/L, respectively. Under the optimal condition, the yield and specific yield of butyric acid reached about 2.58 g/L and 0.36 g/g xylose, respectively, with 75.00% butyric acid in the total volatile fatty acids. As renewable energy, hydrogen was also collected from the xylose fermentation with a yield of about 73.86 mmol/L. The kinetics of growth and product formation indicated that the maximal cell growth rate (μ _m ) and the specific butyric acid yield were 0.1466 h^?1 and 3.6274 g/g cell (dry weight), respectively. The better performance in xylose fermentation showed C. butyricum B10 a potential application in efficient butyric acid production from lignocellulose.     

Influence of Ni(2+) concentration on biohydrogen production

In this paper, the effect of Ni(2+) concentration ranging from 0 to 50mg/L on fermentative hydrogen production by mixed cultures was investigated in batch test. The results showed that at 35 degrees C and initial pH 7.0, Ni(2+) was able to enhance the hydrogen production rate with increasing Ni(2+) concentration from 0 to 0.2mg/L, and enhance the hydrogen production potential and hydrogen yield with increasing Ni(2+) concentration from 0 to 0.1mg/L. The maximum hydrogen production potential of 288.6mL and the maximum hydrogen yield of 296.1mL/g glucose were obtained at the Ni(2+) concentration of 0.1mg/L. In all tests, the major soluble metabolites produced by mixed cultures were ethanol, acetic acid and butyric acid, without propionic acid. Ni(2+) had little effect on the substrate degradation efficiency with increasing concentration from 0 to 50mg/L. Ni(2+) was able to enhance the biomass production yield with increasing Ni(2+) concentration from 0 to 0.1mg/L. The maximum biomass production yield of 232.5mg/g glucose was obtained at the Ni(2+) concentration of 0.1mg/L. In all tests, the final pH after fermentative hydrogen production was lower than the initial pH.     

Integrative Biological Hydrogen Production: An Overview

Biological hydrogen (H₂) production by dark and photo-fermentative organisms is a promising area of research for generating bioenergy. A large number of organisms have been widely studied for producing H₂ from diverse feeds, both as pure and as mixed cultures. However, their H₂ producing efficiencies have been found to vary (from 3 to 8 mol/mol hexose) with physiological conditions, type of organisms and composition of feed (starchy waste from sweet potato, wheat, cassava and algal biomass). The present review deals with the possibilities of enhancing H₂ production by integrating metabolic pathways of different organisms-dark fermentative bacteria (from cattle dung, activated sludge, Caldicellulosiruptor, Clostridium, Enterobacter, Lactobacillus, and Vibrio) and photo-fermentative bacteria (such as Rhodobacter, Rhodobium and Rhodopseudomonas). The emphasis has been laid on systems which are driven by undefined dark-fermentative cultures in combination with pure photo-fermentative bacterial cultures using biowaste as feed. Such an integrative approach may prove suitable for commercial applications on a large scale.     

Effect of culture conditions on lipolytic enzyme production by Penicillium candidum in a solid state fermentation

Lipolytic enzymes were produced using wheat bran as substrate in a solid state fermentation with Penicillium candidum. The best production of lipolytic activity occurred at 29 degrees C. One hundred micromoles of free butyric acid (FBA) was released from tributyrin by 1 mL of cell free supernatant in the absence of control of environmental relative humidity. When a closed chamber saturated with water vapour was used the lipolytic activity increased to 320 micromoles of free butyric acid. The best initial reaction pH was 7.0. The highest activity, 480 micromoles of FBA, was obtained at a moisture content of 67.5 % of saturation.     

转基因衣藻lba及对照藻产氢培养条件的优化

通过对莱茵衣藻849及其转基因衣藻lba进行光照强度、细胞浓度和培养基中硫酸盐含量三因素三水平的正交实验,确定了两个藻种的最佳产氢条件,同时对转基因藻和849产氢培养条件下的光合放氧速率和pH进行了检测。实验结果表明,在25 ℃下,莱茵衣藻849和转基因衣藻lba的最佳产氢条件都为光照强度 60μmol/(m²·s),细胞浓度为叶绿素含量12.5μg/ml,培养基中硫酸盐含量0μmol/L。莱茵衣藻849和转基因衣藻lba的最高氢气产量分别达到了349μl/mg chlorophyll 和634μl/mg chlorophyll。在产氢条件下,转基因藻lba的净光合放氧速率比849低。结果为利用豆血红蛋白特性通过基因工程手段提高莱茵衣藻产氢量提供基础实验数据。     

嗜热子囊菌利用短链有机酸生产角质酶

以嗜热子囊菌(Thermobifida fusca WSH03-11)发酵生产角质酶为模型,研究微生物利用市政污泥厌氧酸化所产短链有机酸为碳源发酵生产高附加值产品的可能。发现：(1)以丁酸、丙酸和乙酸为碳源时,有机酸和氮元素浓度分别为8.0 g/L和1.5 g/L有利于角质酶的生产;而以乳酸为碳源时,最适有机酸和氮源浓度分别为3.0 g/L和1.0 g/L;(2)改变诱导物角质的浓度,以丁酸、丙酸、乙酸和乳酸为碳源,分别比优化前提高了31.0%、13.3%、43.8%和73.2%;(3)在四种有机酸中,T. fusca WSH03-11利用乙酸的速率最快,平均比消耗速率是丙酸的1.3倍,丁酸的2.0倍及乳酸的2.2倍;以丁酸为碳源时的酶活(52.4 U/mL)是乳酸的1.7倍、乙酸的2.5倍和丙酸的3.2倍;角质酶对乳酸的得率(12.70 u/mg)分别是丁酸的1.4倍、丙酸的3.0倍和乙酸的3.8倍;(4)以混合酸为碳源生产角质酶,T. fusca WSH03-11优先利用乙酸,而对丁酸的利用受到抑制。进一步研究发现,混合酸中0.5 g/L的乙酸将导致丁酸的消耗量降低66.7%。这是首次利用混合酸作碳源发酵生产角质酶的研究报道。这一研究结果进一步确证了利用市政污泥厌氧酸化所产有机酸为碳源发酵生产高附加值产品的可行性,为以廉价碳源生产角质酶奠定了良好的基础。     

嗜热子囊菌利用短链有机酸生产角质酶

以嗜热子囊菌(Thermobifida fusca WSH03-11)发酵生产角质酶为模型,研究微生物利用市政污泥厌氧酸化所产短链有机酸为碳源发酵生产高附加值产品的可能。发现：(1)以丁酸、丙酸和乙酸为碳源时,有机酸和氮元素浓度分别为8.0 g/L和1.5 g/L有利于角质酶的生产;而以乳酸为碳源时,最适有机酸和氮源浓度分别为3.0 g/L和1.0 g/L;(2)改变诱导物角质的浓度,以丁酸、丙酸、乙酸和乳酸为碳源,分别比优化前提高了31.0%、13.3%、43.8%和73.2%;(3)在四种有机酸中,T. fusca WSH03-11利用乙酸的速率最快,平均比消耗速率是丙酸的1.3倍,丁酸的2.0倍及乳酸的2.2倍;以丁酸为碳源时的酶活(52.4 U/mL)是乳酸的1.7倍、乙酸的2.5倍和丙酸的3.2倍;角质酶对乳酸的得率(12.70 u/mg)分别是丁酸的1.4倍、丙酸的3.0倍和乙酸的3.8倍;(4)以混合酸为碳源生产角质酶,T. fusca WSH03-11优先利用乙酸,而对丁酸的利用受到抑制。进一步研究发现,混合酸中0.5 g/L的乙酸将导致丁酸的消耗量降低66.7%。这是首次利用混合酸作碳源发酵生产角质酶的研究报道。这一研究结果进一步确证了利用市政污泥厌氧酸化所产有机酸为碳源发酵生产高附加值产品的可行性,为以廉价碳源生产角质酶奠定了良好的基础。     

预处理对泔脚发酵产氢的强化研究

采用热(80℃,15 min)预处理的城市生活垃圾厌氧消化污泥为接种物,考察了不同预处理方法对泔脚中温(36℃)批式发酵产氢的影响。Gompertz模型拟合结果表明:微波850 W,4 min与pH9.0下预处理泔脚的发酵产氢延迟时间λ、最大比产氢率、产氢率、生物气中氢气的最高体积分数分别为:3.47 h,9.43 mL/(g.h),186.23 mL/g及46.0%时,具有更大的产氢优越性。泔脚的发酵产氢过程也是一个酸化过程,发酵产氢结束后,4个预处理方案的发酵产氢余物的pH在4.40~5.00之间,pH均有较大幅度的下降。