Enhanced hydrosen production by insertional inactivation of adhE gene in Klebsiella oxytoca HP1

Ethanol is the main byproduct of anaerobic H2-producing fermentation in Klebsiella oxytoca HP1. Two moles of NAD（P）H are consumed to yield one mole of ethanol that may decrease bacterial hydrogen production. In this article the adhE gene that codes for acetaldehyde dehydrogenase was disrupted for the first time. A homologous recombination vector pTA-Str was constructed in which the adhE gene was disrupted by inserting an aminoglycoside-3＇-adenyltransferase （aadA） gene. As expected, the vector includes the insertion 5＇-adhE-aadA-adhE-3＇. The amplified DNA fragment 5＇-adhE-aadA-adhE-3＇ from pTA-Str was transformed into K. oxytoca HP1 and one recombinant was obtained. PCR analysis of the resulting genomic DNA indicated the appropriate deletion and insertion. Compared with the H2-production of wild type K. oxytoca HP1, the hydrogen yield of the mutant increased by 16.07% and ethanol concentration decreased by 77.47%, suggesting that inactivation of the adhE gene in K. oxytoca HP1 is a potential method for enhancing bacterial H2-production.     

Klebsiella oxytoca HP1乙醇脱氢酶基因敲除对产氢的影响

Klebsiella oxytoca HP1是从温泉筛选得到的很有潜力的产氢菌株。为了进一步提高产氢能力,应用同源重组技术构建了乙醇途径缺少菌株,并分析和比较了野生菌和工程菌的代谢流量分布。     

Klebsiella oxytoca HP1乙醇脱氢酶基因敲除对产氢的影响

Klebsiella oxytcoHP1是从温泉筛选得到的很有潜力的产氢菌株。为了进一步提高产氢能力，应用同源重组技术构建了乙醇途径缺少菌株，并分析和比较了野生菌和工程菌的代谢流量分布。     

产酸克雷伯氏菌氢酶分离提纯与特性的初步研究

采用硫酸铵沉淀和柱层析 (DEAE-Sepharose F.F., Sephacryl S-200, TSK-DEAE)初步分离纯化了产酸克雷伯氏菌(Klebsiella oxytoca)HP1可溶性氢酶,研究了温度、pH值、电子载体等对氢酶催化放氢活性的影响.研究表明,可溶性氢酶催化放氢的最适温度为30℃,催化放氢的最适pH值为7.5,甲基紫晶(MV)是氢酶催化放氢的最适人工电子载体,氧对氢酶催化活性有较大的抑制作用.     

利用克雷伯氏菌进行同步糖化发酵产氢的研究

氢作为一种清洁的能源引起了人们的普遍重视.实验以产酸克雷伯氏菌(Klebsiella oxytoca)HP1为产氢菌株,以稻草粉为产氢底物,进行同步糖化发酵(Simultaneous Saccharification and Fermentation,SSF)产氢.对影响同步糖化发酵产氢的单因子进行试验,选取对氢产率影响较大的因子:温度、pH、纤维素酶用量等进行L9(34)正交试验.结果表明同步糖化发酵产氢的最佳条件为:温度40℃,pH6.5,纤维素酶用量为20FPAU/g稻草粉,摇床转速100r/min,发酵时间42h.在该条件下的最大氢产率为110.6mL/g稻草粉,稻草粉的氢转化率为22%.进行了10L放大发酵产氢试验,最大氢产率为122.3mL/g稻草粉,氢转化率为24.3%.与分步糖化发酵(Separate Hydrolysis and Fermentation,SHF)产氢相比,氢产率提高34.4%.研究表明,利用同步糖化发酵工艺可以提高生物制氢的产量和得率.     

通气提高Klebsiella oxytoca HP1发酵产氢

研究了Klebsiella oxytoca HP1在不同通气条件下的生长和放氢特性．批式发酵实验结果表明：通氩气放氢效果最好，通二氧化碳放氢效果最差．提高氩气通气速率能显著提高产氢量。0．25L／Lmin条件下的产氢量达到1155mL是不通气时的2．41倍，但通气也影响延迟期的长短。氩气通量应该与微生物生长阶段相匹配．代谢产物分析表明：K．oxytoca HP1呈混合酸发酵特性，主要代谢产物有乙酸、乙醇、乳酸和2，3-丁二醇，氩气通气速率明显影响丙酮酸节点的代谢途径和通量，从高通气条件到不通气条件，代谢主要途径按乙酸途径→乙醇途径→乳酸途径的次序转变，通气速率是K．oxytoca HP1发酵产氢的重要调控因子．     

产酸克雷伯氏菌的吸附固定及其产氢研究

利用曲霉(Aspergillussp.XF101)所形成的菌丝球吸附产氢细菌产酸克雷伯氏菌(Klebsiella oxytocaHP1),当曲霉培养时间为50 h,菌丝球直径为1.3~1.8 mm,菌悬液pH值为5.0~6.0,吸附温度为30℃,吸附时间为1.5 h时,可获得最佳吸附效果,吸附率可达99%以上.利用菌丝球固定产氢菌可进行连续产氢,其最大产氢速率为18 mmol/L.h,平均产氢速率为1.7 mmol/L.h,持续产氢时间为15 d.     

蒽醌法生产双氧水工艺爆燃事故防控体系研究

我国主要采用蒽醌法生产工艺生产双氧水。本文通过事故树法深入分析蒽醌法生产工艺爆燃事故的成因,基于4M1E将分析结果进行归类,并给出解决对策,形成蒽醌法生产双氧水工艺爆燃事故防控体系。系统可靠度分析结果显示该防控体系可以有效降低事故发生概率,提高蒽醌法生产双氧水工艺的可靠性。     

Cloning and functional analysis of chloroplast division gene NtFtsZ2-1 in Nicotiana tabacum

FtsZ protein plays an important role in the division of chloroplasts. With the finding and functional analysis of higher plant FtsZ proteins, people have deepened the understanding in the molecular mechanism of chloroplast division. Multiple ftsZ genes are diversified into two families in higher plants, ftsZ1 and ftsZ2. On the basis of the research on ftsZ1 family, we analyzed the function of NtFtsZ2-1 gene in Nicotiana tabacum. Microscopic analysis of the sense and antisense NtFtsZ2-1 transgenic tobacco plants revealed that the chloroplasts were abnormal in size and also in number when compared with wild-type tobacco chloroplasts. Our investigations confirmed that the NtFtsZ2-1 gene is involved in plant chloroplast division.     

活性污泥制氢系统中发酵细菌的分离与鉴定

分离鉴定高效产氢发酵细菌是发酵发生物制氢技术的重要前提,利用Hungater技术与宽体窄颈培养瓶平板技术,以及LM-1和HPB-LR培养基分离鉴定厌氧发酵产氢细菌获得六株产氢细菌,葡萄糖是他们最适宜的底物.他们的产氢代谢为乙醇发酵型.产氢细菌发酵液相末端产物分析表明乙醇和乙酸占其总代谢产物的95?%.生理生化和形态学特征分析表明它们属于一种特殊的微生物类群.16SrDNA碱基序列分析表明它们可以划分为新的种属.     

Salt tolerance conferred by over-expression of OsNHX1 gene in Poplar 84K

OsNHX1 gene (Na^＋/H^＋ antiporter gene of Oryza sativa L.) was introduced into Poplar 84K with Agrobacterium tumefaciens-mediated transformation. PCR, Southern and Northern blot analysis showed that OsNHX1 gene was incorporated successfully into the genome of Poplar 84K and expressed in these transgenic plants. Salt tolerance test showed that three lines of transgenic plants grew normally in the presence of 2OO mmol/L NaCI, while the Na^＋ content in the leaves of the transgenic plants grown at 2OO mmol/L NaCl was significantly higher than that in plants grown at 0mmol/L NaCI. The osmotic potential in the transgenic plants with high salinity treatment was lower than that of control plants. Our results demonstrate the potential use of these transgenic plants for agricultural use in saline soils.     

GaAs1—xPx：N中氮浓度的光吸收法测量

在液氮温度下利用光吸收法测量了一组混晶材料GaAs_(1-x)P_x :(0.60相似文献   

协同增敏同步荧光法测定自来水与人尿中的1-羟基芘

使用正丙醇这一小分子脂肪醇,进一步促进β-环糊精有序介质对1-羟基芘的荧光增强作用,基于此,利用同步荧光法测定水样中的1-羟基芘,检测限达到2.5×10-11m ol/L,相对标准偏差为3.8%(n=5),运用该方法测定了自来水与人尿样品中的1-羟基芘,结果满意。     

重组大肠杆菌高密度发酵表达胰高血糖素样肽-1衍生物(GP62)的培养基优化

对重组E.coli BL21 (DE3)高密度表达胰高血糖素样肽-1衍生物(GP62)的发酵培养基进行了优化.通过单因素实验与正交实验相结合的方法,依次对基础培养基,发酵培养基中碳源、氮源、无机盐等成份进行优化.在2YT培养基基础上,获得优化的发酵培养基2YT-GP62.在5L全自动发酵罐中利用终浓度0.5 mmol/...     

单增李斯特菌致流产小鼠子宫中Th1和Th2细胞因子的变化

为探讨Th1和Th2细胞因子在单增李斯特菌(Listeria monocytogenes,LM)致小鼠流产中的作用,用LM感染妊娠小鼠和小鼠巨噬细胞,统计胚胎存活率,酶联免疫测定(enzyme linked lmmuno sorbent assay,ELISA)小鼠子宫组织中和巨噬细胞培养基中主要的Th1和Th2细胞因子水平.结果显示,LM诱导的流产小鼠子宫中Th1细胞因子水平显著增加,溶血素O(listeriolysin O,LLO)基因缺陷型(Δ hly)LM感染组胚胎存活率和子宫中Th1、Th2细胞因子水平无显著变化;LM感染的巨噬细胞分泌的Th1细胞因子和白细胞介素-4(interleukin, IL-4)水平显著增加,IL-10水平显著降低,Δ hly LM感染组Th1和Th2细胞因子水平无显著变化.因此,LM感染后子宫中Th1/Th2细胞因子失衡诱导了小鼠流产,这可为临床防治LM诱导的流产提供科学依据.     

Physical location ofHelminthosporium carbonum susceptibility gene hm1 by FISH of a RFLP marker umc119 in Maize

A fluorescencein situ hybridization (FISH) procedure was adopted to physically map a RFLP marker, umc119 near the centromere of the long arm of linkage group1 in maize. The hm1 gene (Helminthosporium carbonum susceptibility gene) was linked closely with the marker umc119. RFLP markers are very good landmarks for mapping genes. Therefore, we also determined the position of the gene hm1 on the chromosome based on the physical location of umc119. The disease induced by infection ofHelminthosporium carbonum is one of the serious maize diseases and it distributes in many countries including China. Hybridization sites were showed on 1 L (long arm of chromosome1) and 5 L. The percentage distance from centromere to the hybridization site was 22.86 on 1 L and 58.23 on 5 L the detection rate was about 12% for mitotic cells. In interphase nuclei five hybridized sites were detected. It demonstrated that umc119 was multiplicated sequences. FISH has more advantages overin situ hybridization (ISH) detected by DAB for increasing the detection ratio and contrast between chromosomes and hybridization signals. The ability to detect the hybridization signal of a small low copy DNA sequence is a very important key towards wide application of FISH for plant genome mapping. Supported by the National Natural Science Foundation and Doctorate Vesting Point Foundation of the Education Committee of China Li Lijia: born in 1967. Ph. D.     

超临界CO2条件下碱性添加物对大晶粒TS-1催化丙烯环氧化反应的影响

为解决在超临界CO2(scCO2)反应介质中,大晶粒钛硅分子筛(TS–1)催化丙烯环氧化制备环氧丙烷(PO)的反应存在的H2O2分解和环氧丙烷选择性较低等问题,研究了添加氢氧化钠、碳酸氢钠、尿素和碳酸铵等碱性组分对反应的影响.在加入各碱性组分后,环氧丙烷选择性均有了不同程度的提高,缓解了H2O2的分解及副产物生成,在加入0.054,1,mmol碳酸铵后,H2O2转化率、PO选择性和H2O2利用率分别达到了98.7%9、5.2%和94.3%.     

ERK1／2通路和血管内皮细胞在15-KETE诱导缺氧大鼠肺动脉收缩中的作用

目的用组织浴槽血管环技术研究细胞外信号调节激酶1／2（extracellularregulatedproteinkinasesl／2,ERKl／2）通路和血管内皮细胞在15-KETE诱导缺氧大鼠肺动脉收缩中的作用。方法16只体质量为（220±20）g清洁级Wistar大鼠随机分为2组（n=8）,正常对照组置于正常环境中饲养（FiO,=21％）,缺氧组置于缺氧的培养箱中饲养（FiO2：10％）,连续饲养9d后处死,游离直径约为0．5—1．0inIn肺内肺动脉（PA）。剪成3mm长的动脉环,在组织浴槽内进行张力研究。比较在15一KETE给药前后肺动脉环张力变化;机械法去除动脉环内皮,比较内皮完整和去内皮后,15一KETE对缺氧性肺动脉环的收缩作用;用ERKl／2上游激酶抑制剂U0126孵育肺动脉环,比较U0126孵育前后15-KETE对缺氧性肺动脉环的收缩作用;机械法去除动脉环内皮,再比较U0126孵育前后15-KETE对缺氧性肺动脉环的收缩作用。结果1）15-KETE对缺氧大鼠肺动脉环有收缩作用,呈浓度-效应关系,与正常对照组比较差异显著（P〈0．05）;2）内皮完整和内皮去除的肺动脉环,15-KETE对其缩血管作用均受到抑制,但差异显著（P〈0．05）;3）内皮完整肺动脉环,在U0126孵育前后,15-KETE的缩血管作用均受到抑制,但差异显著（P〈0．05）;4）内皮去除的肺动脉环,U0126孵育前后,15-KETE的缩血管作用也受到抑制,差异显著（P〈0．05）。结论15-KETE可浓度依赖性地收缩缺氧大鼠肺动脉环;15-KETE引起缺氧肺动脉收缩可能与ERK1／2信号转导通路和血管内皮细胞有关,并且位于平滑肌的ERKl／2通路也参与15-KETE诱导缺氧大鼠肺动脉环的收缩。