共查询到20条相似文献,搜索用时 140 毫秒
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微生物降解褐煤的酶学机理 总被引:3,自引:0,他引:3
褐煤是燃烧值较低的劣质煤 ,工业用途主要是直接燃烧 ,但直接利用伴随着许多环境问题 ,如褐煤燃烧过程中会释放含硫及含氮废气对大气造成污染。自 1982年Cohen和Gabriele首次报道 2株担子菌Polyporusversicolor和Poriamonticolor能将褐煤转化成黑色液滴[1] 开始 ,许多人开始研究利用生物技术将褐煤转化成洁净、有效的能源或其它生物产品。褐煤是由芳香化环组成并由盐桥、脂肪链等连接起来的大分子网状结构化合物 ,很难进入微生物细胞中 ,所以褐煤的微生物降解是由微生物分泌到细胞外的物质… 相似文献
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Kornél L. Kovács Ákos T. Kovács Gergely Maróti Zoltán Bagi Gyula Csanádi Katalin Perei Balázs Bálint Judit Balogh András Fülöp Lívia S. Mészáros András Tóth Réka Dávid Dóra Latinovics András Varga Gábor Rákhely 《Reviews in Environmental Science and Biotechnology》2004,3(4):321-330
H2 is considered as the ultimate cleanest energy carrier to be generated from renewable sources. This minireview intends to point out that in addition to this function, biologically produced hydrogen is important for environmental biotechnological applications. The purple sulphur phototrophic bacterium, Thiocapsa roseopersicina BBS contains several NiFe hydrogenases. These enzymes can be used e.g., as fuel cell H2 splitting catalyst or in photoheterotrophic H2 production. Microorganisms that supply H2 in situ facilitate the biodegradation of organic material and concomitant biogas production. Fast, efficient, and economic treatment of organic waste, sludge, manure is achieved and generation of significant amount of renewable fuel from waste is intensified. The technology has been field tested under mesophilic and thermophilic conditions with positive results. 相似文献
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Mark D Redwood Iryna P Mikheenko Frank Sargent Lynne E Macaskie 《FEMS microbiology letters》2008,278(1):48-55
Escherichia coli can perform at least two modes of anaerobic hydrogen metabolism and expresses at least two types of hydrogenase activity. Respiratory hydrogen oxidation is catalysed by two 'uptake' hydrogenase isoenzymes, hydrogenase -1 and -2 (Hyd-1 and -2), and fermentative hydrogen production is catalysed by Hyd-3. Harnessing and enhancing the metabolic capability of E. coli to perform anaerobic mixed-acid fermentation is therefore an attractive approach for bio-hydrogen production from sugars. In this work, the effects of genetic modification of the genes encoding the uptake hydrogenases, as well as the importance of preculture conditions, on hydrogen production and fermentation balance were examined. In suspensions of resting cells pregrown aerobically with formate, deletions in Hyd-3 abolished hydrogen production, whereas the deletion of both uptake hydrogenases improved hydrogen production by 37% over the parent strain. Under fermentative conditions, respiratory H2 uptake activity was absent in strains lacking Hyd-2. The effect of a deletion in hycA on H2 production was found to be dependent upon environmental conditions, but H2 uptake was not significantly affected by this mutation. 相似文献
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Xianzheng Yuan Xiaoshuang Shi Peidong ZhangYueli Wei Rongbo Guo Lisheng Wang 《Bioresource technology》2011,102(19):9007-9012
This study investigated the influence of particle size on anaerobic biohydrogen production from wheat stalk by mixed microflora. In addition, the kinetic model for the formation of main products was also mentioned. The results demonstrated that all the cumulative productions of hydrogen, acetate and butyrate decreased as the particle size increasing from 1 to 10 mm at a constant TS value of 2%, 5% and 8%, respectively. However, this difference for aqueous products was not very obvious compared with hydrogen. A modified Gompertz equation was able to adequately describe the cumulative production of hydrogen, acetate and butyrate (R2 higher than 0.989). The results also indicated that the formation of the main products were all associated with the degradation of cellulose and hemicellulose (R2 higher than 0.855). 相似文献
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Hydrogenases are metalloproteins capable of catalyzing the interconversion between molecular hydrogen and protons and electrons. The iron–sulfur clusters within the enzyme enable rapid relay of electrons which are either consumed or generated at the active site. Their unparalleled catalytic efficiency has attracted attention, especially for potential use in H2 production and/or fuel cell technologies. However, there are limitations to using hydrogenases, especially due to their high O2 sensitivity. The subclass, called [FeFe] hydrogenases, are particularly more vulnerable to O2 but proficient in H2 production. In this review, we provide an overview of mechanistic and protein engineering studies focused on understanding and enhancing O2 tolerance of the enzyme. The emphasis is on ongoing studies that attempt to overcome O2 sensitivity of the enzyme while it catalyzes H2 production in an aerobic environment. We also discuss pioneering attempts to utilize the enzyme in biological H2 production and other industrial processes, as well as our own perspective on future applications. 相似文献
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氮代谢参与植物逆境抵抗的作用机理研究进展 总被引:2,自引:0,他引:2
近年来,植物所受到的诸如干旱、盐、高温、低氧、重金属胁迫和营养元素缺乏等环境胁迫越来越多,严重影响了植物的生长发育及作物的质量和产量。氮素是植物生长发育所需的必需营养元素,同时也是核酸、蛋白质和叶绿素的重要组成成分,其代谢过程与植物抵抗逆境的能力息息相关。氮代谢是指植物对氮素的吸收、同化和利用的全过程,是植物体内基础代谢途径之一。氮代谢主要从氮素吸收、同化及氨基酸代谢等方面参与植物的抗逆性,并通过调节离子吸收和转运、稳定细胞形态和蛋白质结构、维持激素平衡和细胞代谢水平、减少体内活性氧(reactive oxygen species,ROS)生成以及促进叶绿素合成等生理机制来影响植物抵抗非生物胁迫的能力。因此,提高植物在逆境下的氮代谢水平是减轻外界胁迫对其损伤的一种潜在途径。该文从氮素同化的基本途径出发,分别阐述了氮代谢在干旱胁迫、盐胁迫和高温胁迫等多个方面的逆境抵抗过程中的作用机理,为氮代谢参与植物抗逆性研究提供了有利参考。 相似文献
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Dynamic modelling of high biomass density cultivation and biohydrogen production in different scales of flat plate photobioreactors 下载免费PDF全文
Dongda Zhang Pongsathorn Dechatiwongse Ehecatl Antonio del Rio‐Chanona Geoffrey C. Maitland Klaus Hellgardt Vassilios S. Vassiliadis 《Biotechnology and bioengineering》2015,112(12):2429-2438
This paper investigates the scaling‐up of cyanobacterial biomass cultivation and biohydrogen production from laboratory to industrial scale. Two main aspects are investigated and presented, which to the best of our knowledge have never been addressed, namely the construction of an accurate dynamic model to simulate cyanobacterial photo‐heterotrophic growth and biohydrogen production and the prediction of the maximum biomass and hydrogen production in different scales of photobioreactors. To achieve the current goals, experimental data obtained from a laboratory experimental setup are fitted by a dynamic model. Based on the current model, two key original findings are made in this work. First, it is found that selecting low‐chlorophyll mutants is an efficient way to increase both biomass concentration and hydrogen production particularly in a large scale photobioreactor. Second, the current work proposes that the width of industrial scale photobioreactors should not exceed 0.20 m for biomass cultivation and 0.05 m for biohydrogen production, as severe light attenuation can be induced in the reactor beyond this threshold. Biotechnol. Bioeng. 2015;112: 2429–2438. © 2015 The Authors. Biotechnology and Bioengineering Published by Wiley Peiodicals, Inc. 相似文献
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利用代谢工程手段改造克雷伯菌Klebsiella sp.HQ-3产氢途径中相关代谢调控因子及辅酶因子,以构建高效产氢工程菌。利用简并引物,以Klebsiella sp.总DNA为模板,克隆了甲酸-氢裂解酶系统的全局转录调控因子(FNR)fnr基因、编码甲酸脱氢酶(FDH-H)fdhF基因,以及NADH途径中编码烟酸转磷酸核糖激酶(NAPRTase)的pncB基因,构建了3种同源过表达重组菌株HQ-3-fnr、HQ-3-fdhF和HQ-3-pncB,以研究同源过表达产氢代谢调控因子及辅酶因子对克雷伯菌累积产氢、细胞生长、代谢终产物的影响。结果表明,过表达fnr、pncB和fdhF基因的克雷伯工程菌的产氢效率比携带空载体的克雷伯对照菌株分别提高12.26%、11.62%和7.28%;重组菌HQ-3-fnr、HQ-3-fdhF和HQ-3-pncB的葡萄糖利用率较克雷伯对照菌株HQ-3-C明显增加,过表达fnr、fdhF基因使代谢合成甲酸量增多;过表达pncB基因能促进NADH合成,使更多的NADH流入消耗NADH较多的乙醇与琥珀酸代谢路径,使得乙醇和琥珀酸含量增加,而乳酸含量降低。 相似文献
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To study the structure of microbial communities in the biological hydrogen production reactor and determine the ecological
function of hydrogen producing bacteria, anaerobic sludge was obtained from the continuous stirred tank reactor (CSTR) in
different periods of time, and the diversity and dynamics of microbial communities were investigated by denaturing gradient
gel electrophoresis (DGGE). The results of DGGE demonstrated that an obvious shift of microbial population happened from the
beginning of star-up to the 28th day, and the ethanol type fermentation was established. After 28 days the structure of microbial
community became stable, and the climax community was formed. Comparative analysis of 16S rDNA sequences from reamplifying
and sequencing the prominent bands indicated that the dominant population belonged to low G+C Gram-positive bacteria (Clostridium sp. andEthanologenbacterium sp.), β-proteobacteria (Acidovorax sp.), γ-proteobacteria (Kluyvera sp.), Bacteroides (uncultured bacterium SJA-168), and Spirochaetes (uncultured eubacterium E1-K13), respectively. The hydrogen
production rate increased obviously with the increase ofEthanologenbacterium sp.,Clostridium sp. and uncultured Spirochaetes after 21 days, meanwhile the succession of ethanol type fermentation was formed. Throughout
the succession the microbial diversity increased however it decreased after 21 days. Some types ofClostridium sp.Acidovorax sp.,Kluyvera sp., and Bacteroides were dominant populations during all periods of time. These special populations were essential for the
construction of climax community. Hydrogen production efficiency was dependent on both hydrogen producing bacteria and other
populations. It implied that the cometabolism of microbial community played a great role of biohydrogen production in the
reactors. 相似文献
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益生菌及益生元调节骨代谢的研究进展 总被引:1,自引:0,他引:1
骨质疏松症已成为威胁中老年人健康的主要疾病之一,越来越多的人受到该病症的危害.肠道菌群是定殖在机体肠道内,与宿主形成共生关系的微生物,对宿主的免疫及代谢等产生重要影响,研究发现,肠道菌群与骨代谢之间存在密切关系,本文从肠道菌群与免疫、骨代谢与免疫、肠道菌群与骨代谢、益生菌及益生元调节骨代谢等几个方面阐述,肠道菌群有望成为骨质疏松症治疗的一个新靶点,通过益生菌或益生元来干预肠道菌群组成,进而调节免疫系统状态,抑制促炎因子的生成,从而降低骨吸收作用,达到预防和治疗骨质疏松症的目的. 相似文献
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Abstract Hydrogenase activity was characterized in cell extracts of Propionispira arboris that consumed or produced H2 , coupled to methyl viologen reduction, and displayed highest levels (2.6 μmol/min/mg protein) in extracts prepared from fumarate-grown cells. Reversible hydrogenase activity in cell extracts correlated with the production of low levels of hydrogen during the growth phase and its subsequent consumption during the stationary phase of cells grown on glucose or lactate as the carbon and energy source. The addition of exogenous hydrogen to glucose, lactate or fumarate-grown cells dramatically increased propionate production at the expense of acetate formation. This accounted for the formation of propionate as nearly the sole end product of glucose fermentation under two atmospheres of hydrogen. The physiological function of hydrogenase in regulation of carbon and electron flow, and the significance of the results in applied and environmental microbiology are discussed. 相似文献