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酶具有专一性与高效性,酶法工艺比传统工艺更节省原料和能源且应用广泛。以往对酶法工艺进行了大量的比较环境评估研究,以考查酶法工艺是否可以改善环境、促进清洁生产。总结并对环境评估的发展和技术实施提出建议。生命周期评估(LCA)作为一种评估工具被广泛使用,而"碳足迹"及环境影响评估(EIA)仅限于少数研究。全球气候变暖目前被视为一个评价指标,此外,一些研究也将其他影响因素视为评价指标。研究结果证实:酶法工艺替代传统工艺,可减少全球气候变暖、酸化、富营养化、光化学臭氧的形成和能源的消耗。酶法工艺能节省矿物燃料和无机化学原料。酶技术在促进工业清洁生产方面有着巨大的潜力。 相似文献
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降解三硝基甲苯的酵母和类酵母菌的研究 总被引:9,自引:0,他引:9
从受三硝基甲苯(TNT)严重污染的土壤和废水中分离筛选到17株可降解TNT的酵母菌和白地霉。其中6株为克鲁斯假丝酵母(Candidakrusei),4株为橡树假丝酵母(C.quercitrusa),一株为无名假丝酵母(C.famata),一株为伯杰汉逊酵母(Hansenulabeijerinckii),一株为亚膜汉逊酵母(H.subpelliculosa),4株为白地霉(Geotrichumcandidum)。对其中6株菌进行了降解TNT的条件实验,发现降解TNT的适宜pH为7,温度为37~40℃。在含75~80mg/LTNT的培养基中,40h内能降解TNT56~74mg/L,去除率达71%~93%。在培养基中加入0.01%~0.05%的葡萄糖作碳源,或加入0.01%~0.1%的酵母膏对6株菌降解TNT的能力略有促进作用。加入铵盐作为氮源则明显抑制这些菌对TNT的降解。 相似文献
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本研究采用酸法、碱法、酶法和微波法对灵芝β-葡聚糖进行降解,通过降解率、产物分子量变化、产物聚合度分布等指标比较了不同方法的降解效果。结果表明,微波法降解率高达94%,处理后产物的分子量明显降低,寡糖产物聚合度分布广。酶法降解率约为40%,寡糖产物中含有DP2-5的成分。酸法及碱法降解率低于20%,寡糖产物少。研究表明,与其他3种方法相比,微波法降解率高、产物丰富、操作条件易于控制,是一种简单、高效的降解灵芝β-葡聚糖、制备灵芝β-葡寡糖的方法。 相似文献
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糖基化是生物体中最重要的反应之一,通过糖基化作用可以形成具有多种生物功能的糖缀合物。糖核苷酸作为Leloir型糖基转移酶催化的转糖基反应的糖基供体,在聚糖和糖缀合物的生物合成中必不可少。然而,糖核苷酸的成本较高、可用性有限等因素阻碍了生物催化级联反应在工业中大规模的应用。因此,人们越来越关注糖核苷酸的合成策略,以实现其在多种领域的广泛应用。目前,糖核苷酸及其衍生物的化学合成方法已经建立起来,但合成反应的产量通常很低,而酶法(化学-酶法)和细胞工厂法在合成糖核苷酸过程中具有显著优势。本文主要围绕哺乳动物中常见的9种糖核苷酸,概述了其类型和结构、酶法(化学-酶法)和细胞工厂法两种制备方法。伴随糖核苷酸的高效合成,其多种功能逐渐被发现和应用。本文进一步概述了糖核苷酸在聚糖及糖缀合物合成、糖基转移酶生化性质表征以及生物正交标记策略等方面的应用,对生物化学、糖生物学的研究以及相关医药产品的研发具有十分重要的意义。 相似文献
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Energetic compounds have been used in a variety of industrial and military applications worldwide leading to widespread environmental
contamination. Many of these compounds are toxic and resist degradation by oxidative enzymes resulting in a need for alternative
remediation methods. It has been shown that trinitrotoluene (TNT)-contaminated soil subjected to treatment in strictly anaerobic
bioreactors results in tight binding of TNT transformation products to soil organic matter. The research presented here examined
the fate of TNT and its metabolites in bioreactors under three different aeration regimes. In all treatment regimes, the typical
metabolites of aminodinitrotoluenes and diaminonitrotoluenes were observed prior to irreversible binding into the soil fraction
of the slurry. Significant transformation of TNT into organic acids or simple diols, as others report in prior work, was not
observed in any of the treatments and is an unlikely fate of TNT in anaerobic soil slurries. These results indicate that aeration
does not dramatically affect transformation or fate of TNT in reactor systems that receive a rich carbon source but does affect
the rate at which metabolites become tightly bound to the soil. The most rapid transformations and lowest redox potentials
were observed in reactors in which an aerobic headspace was maintained suggesting that aerobes play a role in establishing
conditions that are most conducive to TNT reduction. 相似文献
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Gibson S. Nyanhongo Marc Schroeder Walter Steiner Georg M. Gü bitz 《Biocatalysis and Biotransformation》2005,23(2):53-69
Enzymatic degradation of TNT by aerobic bacteria is mediated by oxygen insensitive (Type 1) or by oxygen sensitive nitroreductases (Type II nitroreductases). Transformation by Type I nitroreductases proceeds through two successive electron reductions either by hydride addition to the aromatic ring or by direct nitro group reduction following a ping pong kinetic mechanism. TNT is reduced to the level of hydroxylaminodinitrotoluenes and aminodinitrotoluenes by pure enzyme preparations without achieving mineralization. Interestingly, database gene and amino acid sequence comparisons of nitroreductases reveal a close relationship among all enzymes involved in TNT transformation. They are all flavoproteins which use NADPH/NADH as electron donor and reduce a wide range of electrophilic xenobiotics. TNT degradation by fungi is initiated by mycelia bound nitroreductases which reduce TNT to hydroxylaminodinitrotoluenes and aminodinitrotoluenes. Further degradation of these products and mineralization is achieved through the activity of oxidative enzymes especially lignin degrading enzymes (lignin and manganese peroxidases). 相似文献
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Gibson S. Nyanhongo Marc Schroeder Walter Steiner 《Biocatalysis and Biotransformation》2013,31(2):53-69
Enzymatic degradation of TNT by aerobic bacteria is mediated by oxygen insensitive (Type 1) or by oxygen sensitive nitroreductases (Type II nitroreductases). Transformation by Type I nitroreductases proceeds through two successive electron reductions either by hydride addition to the aromatic ring or by direct nitro group reduction following a ping pong kinetic mechanism. TNT is reduced to the level of hydroxylaminodinitrotoluenes and aminodinitrotoluenes by pure enzyme preparations without achieving mineralization. Interestingly, database gene and amino acid sequence comparisons of nitroreductases reveal a close relationship among all enzymes involved in TNT transformation. They are all flavoproteins which use NADPH/NADH as electron donor and reduce a wide range of electrophilic xenobiotics. TNT degradation by fungi is initiated by mycelia bound nitroreductases which reduce TNT to hydroxylaminodinitrotoluenes and aminodinitrotoluenes. Further degradation of these products and mineralization is achieved through the activity of oxidative enzymes especially lignin degrading enzymes (lignin and manganese peroxidases). 相似文献
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Ben Stenuit Laurent Eyers Saïd El Fantroussi Spiros N. Agathos 《Reviews in Environmental Science and Biotechnology》2005,4(1-2):39-60
2,4,6-trinitrotoluene (TNT) is known to be one of the most common military explosives. In spite of its established toxicity
and mutagenicity for many organisms, soils and groundwater are still being frequently contaminated at manufacturing, disposal
and TNT destruction sites. The inability of natural aquatic and soil biota to use TNT as growth substrate has been recognized
as the primary limitation in the application of bioremediation processes to contaminated environments. However, promising
degradation pathways have been recently discovered which may lead to the mineralisation of TNT. Significant advances have
been made in studying the mechanism of TNT denitration, which can be considered as the major reaction and the driving force
towards beneficial biodegradation. The possibilities to favour TNT denitration are discussed based on current knowledge of
the enzymology and genetics of denitration in nitroaromatic degrading organisms. The literature survey demonstrates that the
only enzymes characterized so far for their denitrase activity towards TNT belong to the class I flavin-dependent β/α barrel oxidoreductases, also known as the “Old Yellow Enzyme” family. In addition, this review provides an overview of strategies
and future directions towards a rational search for new catabolic activities, including metagenomic library screening, plus
new possibilities to improve the activity of known catabolic enzymes acting on TNT, such as DNA shuffling. 相似文献
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The explosive 2,4,6-trinitrotoluene (TNT) is considered a toxic environmental pollutant that contaminates the soil and ground water. The white rot fungus Phanerochaete chrysosporium is well known for the degradation of TNT under ligninolytic condition. Very few, if any, studies have been done using other white rot fungi. In this study four fungal species, namely, P. chrysosporium, Kuehneromyces mutabilis, Hypholoma fasciculare, and Phlebia radiata, were used to investigate TNT degradation. All fungi were grown under ligninolytic (low-nitrogen) and nonligninolytic (high-nitrogen) conditions containing 25 parts per million (ppm) (0.11 mM) of TNT. Analysis by high-performance liquid chromatography (HPLC) showed biotransformation of TNT under both conditions. Complete degradation occurred under ligninolytic conditions (peroxidase enzymes were present) by P. chrysosporium and P. radiata. A nitrite release assay at 6 days indicated the denitrifying abilities of all the tested varieties of white rot fungi. For both ligninolytic and non-ligninolytic conditions, mass-balance studies showed biotransformation of 0.5 μ Ci 14C-labeled TNT with pregrown mycelial pellets of all fungal species, in which 5% to 15% of the TNT was converted to CO2. These studies show that TNT may be degraded by several other species of white rot fungi and provided additional information on the biodegradation of nitroaromatic compounds in the environment. 相似文献
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Up to 200 mg 2,4,6-trinitrotoluene (TNT) l–1 was removed within 12 h after adding it to a 5-day old culture of Irpex lacteus. The initial formation of hydroxylamino-dinitrotoluenes (2- and 4-OHAmDNT) from TNT was detected, followed by their successive transformation to aminodinitrotoluenes (2- and 4-AmDNT). Transformation of TNT to AmDNT via OHAmDNT was fast, but the next step was slow and seemed to be a rate-limiting step in TNT degradation. OHAmDNT isomers were also rapidly transformed by an in vitro enzymatic system. Both the mycelium and extracellular enzymes of I. lacteus were required for the TNT degradation. 相似文献
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Williams RE Rathbone DA Scrutton NS Bruce NC 《Applied and environmental microbiology》2004,70(6):3566-3574
Several independent studies of bacterial degradation of nitrate ester explosives have demonstrated the involvement of flavin-dependent oxidoreductases related to the old yellow enzyme (OYE) of yeast. Some of these enzymes also transform the nitroaromatic explosive 2,4,6-trinitrotoluene (TNT). In this work, catalytic capabilities of five members of the OYE family were compared, with a view to correlating structure and function. The activity profiles of the five enzymes differed substantially; no one compound proved to be a good substrate for all five enzymes. TNT is reduced, albeit slowly, by all five enzymes. The nature of the transformation products differed, with three of the five enzymes yielding products indicative of reduction of the aromatic ring. Our findings suggest two distinct pathways of TNT transformation, with the initial reduction of TNT being the key point of difference between the enzymes. Characterization of an active site mutant of one of the enzymes suggests a structural basis for this difference. 相似文献
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Biotransformation of Explosives by the Old Yellow Enzyme Family of Flavoproteins 总被引:7,自引:4,他引:3 下载免费PDF全文
Richard E. Williams Deborah A. Rathbone Nigel S. Scrutton Neil C. Bruce 《Applied microbiology》2004,70(6):3566-3574
Several independent studies of bacterial degradation of nitrate ester explosives have demonstrated the involvement of flavin-dependent oxidoreductases related to the old yellow enzyme (OYE) of yeast. Some of these enzymes also transform the nitroaromatic explosive 2,4,6-trinitrotoluene (TNT). In this work, catalytic capabilities of five members of the OYE family were compared, with a view to correlating structure and function. The activity profiles of the five enzymes differed substantially; no one compound proved to be a good substrate for all five enzymes. TNT is reduced, albeit slowly, by all five enzymes. The nature of the transformation products differed, with three of the five enzymes yielding products indicative of reduction of the aromatic ring. Our findings suggest two distinct pathways of TNT transformation, with the initial reduction of TNT being the key point of difference between the enzymes. Characterization of an active site mutant of one of the enzymes suggests a structural basis for this difference. 相似文献
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Elizabeth L Rylott Vanda Gunning Kyriakos Tzafestas Helen Sparrow Emily J Johnston Andrew S Brentnall Jennifer R Potts Neil C Bruce 《Plant signaling & behavior》2015,10(1)
Our recent study highlights the role of 2 glutathione transferases (GSTs) in the
detoxification of the environmental pollutant, 2,4,6-trinitrotoluene (TNT) in
Arabidopsis thaliana. TNT is toxic and highly resistant to
biodegradation in the environment, raising both health and environmental concerns. Two
GSTs, GST-U24 and GST-U25, are upregulated in response to TNT treatment, and expressed
predominantly in the root tissues; the site of TNT location following uptake. Plants
overexpressing GST-U24 and GST-U25 exhibited significantly enhanced ability to withstand
and detoxify TNT, and remove TNT from contaminated soil. Analysis of the catalytic
activities of these 2 enzymes revealed that they form 3 TNT-glutathionyl products. Of
particular interest is 2-glutathionyl-4,6-dinitrotoluene as this represents a potentially
favorable step toward subsequent degradation and mineralization of TNT. We demonstrate how
GSTs fit into what is already known about pathways for TNT detoxification, and discuss the
short and longer-term fate of TNT conjugates in planta. 相似文献
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In this study, the enhanced degradation of TNT using cultures of genome-shuffled Stenotrophomonas maltophilia OK-5 mt-3 has been examined and the proteome of shuffled strain was compared to the wild-type OK-5 strain. Genome shuffling
of S. maltophilia OK-5 was used to achieve a rapid enhancement of TNT degradation. The initial mutant population was generated by NTG treatment
and UV irradiation. The wild-type OK-5 strain was able to degrade 0.2 mM TNT within 6 days, yet barely tolerated 0.5 mM TNT
while the shuffled OK-5 mt-3 was capable of completely degrading 0.5 mM TNT within 8 days, and 1.2 mM within 24 days. The
proteomic analysis of the shuffled OK-5 mt-3 demonstrated the changes in the expression levels of certain proteins compared
to wild-type OK-5. These results provide clues for understanding TNT tolerance and improved TNT degradation by shuffled S. maltophilia OK-5 mt-3 and have possible applications in the processing of industrial waste containing relatively high TNT concentrations. 相似文献