典型短链烯烃的微生物降解转化机制研究进展

烯烃是一类含有碳-碳双键的不饱和烃类物质,广泛存在于自然过程和人为活动中。结构的差异导致不同烯烃具有不同的功能和特点。例如,乙烯是植物生长发育的基本调节物质;丙烯是工业制造聚丙烯和丙烯腈的关键原料;1,3-丁二烯主要用于合成橡胶和塑料,是一级致癌物;而异戊二烯是排放产量最大的非甲烷生物源挥发性有机物,对全球气候变化具有重要影响。微生物在烯烃的降解与转化中起着关键作用,研究这些微生物的作用有助于更好地理解烯烃在环境中的寿命、归趋及影响,这对于地球化学循环的研究及污染场地的修复具有重要意义。本文首先总结了5种典型短链烯烃(乙烯、丙烯、丁烯、1,3-丁二烯、异戊二烯)的微生物好氧与厌氧的降解和转化的机制,发现烯烃降解菌株的分布十分广泛,涵盖多个微生物分类,但微生物对不同烯烃的降解具有一定的共性。例如,在有氧条件下,短链烯烃通常首先被烯烃单加氧酶氧化,生成的产物随后与辅酶M或谷胱甘肽结合后,经过一系列酶促转化后最终进入微生物的中心代谢途径。而在无氧条件下,短链烯烃则可被产乙酸菌、产甲烷菌等微生物通过加氢反应进行转化。通过总结微生物对常见短链烯烃的降解和转化机制,旨在强调微生物在烯烃污染场地生物修复中的重要作用,并加深对微生物在地球化学循环和全球气候变化中贡献的理解,以此推动可持续发展和资源的有效利用。     

氯酚类化合物的微生物降解研究进展

综述了近年在具有降解氯酚类化合物能力的微生物的筛选、氯酚类化合物的好氧和厌氧降解机制以及现代生物技术的开发利用研究．阐述了氯酚类化合物在不同条件下的降解路径．在好氧条件下,单氯酚和二氯酚在氧化酶的攻击下形成氯代邻二酚,邻二酚开环生成相应的氯代粘康酸或半醛,粘康酸内酯化过程中释放氯离子;高度氯代的化合物则是在氢氧化酶作用下生成氯代醌,并逐步脱去所有的氯原子生成苯酚后才开环．在厌氧或缺氧条件下,氯酚进行还原脱氯,在得到电子的同时去掉一个氯取代基．     

长链烷烃降解菌的降解特性

对长链烷烃降解菌的降解能力和摄取模式进行了研究。评价14株烃降解菌利用中长链烃生长的能力,发现只有少数烃降解菌能够获得良好生长,其中Mycobacterium fortuitum514,Pseudomonas aeruginosa1785和Pseudomonas marginata766等3株菌能够高效降解C20到C33的长链烷烃。辛烷不能支持这些长链烷烃降解菌的生长,说明其烃氧化酶与Pseudomonas oleovorans的OCT质粒编码的单氧酶不同。此外,M.fortuitum不产胞外表面活性剂,而P.aeruginosa和P.marginata则是表面活性剂产生菌,然而三者在以烃为碳源生长时均显示出很高的细胞表面疏水性。根据生长现象分析3株菌采用了不同的烷烃摄取模式。     

微生物降解石油烃的功能基因研究进展

微生物对石油烃的降解在自然衰减去除土壤和地下水石油烃污染的过程中发挥了重要作用。微生物通过其产生的一系列酶来利用和降解这类有机污染物,其中,编码关键降解酶的基因称为功能基因。功能基因可作为生物标志物用于分析环境中石油烃降解基因的多样性。因此,研究石油降解功能基因是分析土著微生物群落多样性、评价自然衰减潜力与构建基因工程菌的重要基础。本文主要介绍了烷烃和芳香烃在有氧和无氧条件下的微生物降解途径,重点总结了烷烃和芳香烃降解的主要功能基因及其作用,包括参与羟化作用的单加氧酶和双加氧酶基因、延胡索酸加成反应的琥珀酸合酶基因以及中心中间产物的降解酶基因等。     

石油烃类的微生物降解

石油作为重要能源之一已被世界各国广泛使用,由于在石油的开采、储存、运输、加工和石化产品生产等过程中的漏油以及突发性泄油事故致使大量的石油进入环境造成污染。石油污染的危害主要表现在对土壤生态系统的结构和功能的破坏,严重影响土壤的透气性和渗水性,导致土壤板结、肥力下降;在水体表面形成油膜,致使水中溶氧量急剧下降,造成水生生物的大量死亡,破坏水生生态环境和渔业资源;还可进入地下水系,直接污染地下水源,影响居民用水和农田灌溉;石油中的一些致畸致癌物质还可通过食物链的生物富集作用而直接危害人类健康。随着人们对环境问题的日益关注,石油烃类的微生物降解研究工作也不断得以深入。近十年来这一领域又有许多研究和相关报道,本文对相关工作进行了综述。     

石油烃污染及修复过程中的微生物分子生态学研究进展

针对环境中广泛存在的石油烃污染问题,从分子生态学的角度总结石油烃降解过程中的微生物生态学研究进展。着重介绍分子生态学的研究方法及与石油烃降解相关的降解基因和基因芯片的最新研究进展,同时对存在的问题和今后的研究方向进行总结。     

厌氧微生物降解多环芳烃研究进展

多环芳烃(PAHs)是一类普遍存在于环境介质中的难降解有机污染物,相对于好氧微生物降解PAHs的研究,厌氧微生物降解PAHs的研究则相对较少.本文从厌氧微生物降解PAHs的研究背景,厌氧降解微生物的特点和不同厌氧降解还原反应体系的角度综述了厌氧微生物降解PAHs的概况;结合厌氧微生物降解萘和菲转化途径的介绍,推断了其降解机制的内在原因;同时通过总结影响厌氧微生物降解PAHs的主要因素(包括:PAHs的生物可利用性、外源营养物质的添加、外源电子受体的添加、特定厌氧降解菌的筛选强化和部分环境因素等),指出了制约降解进程的潜在限制因子;并对厌氧微生物降解PAHs研究目前存在的问题和未来的发展方向作了简述与展望.     

烷烃降解基因alk研究进展

很多微生物都可以利用直链烷烃作为唯一碳源和能源 ,目前对该代谢机理的遗传学研究已相当深入。其典型菌株Pseudomonasputida可利用C6～C1 2的烷烃 ,编码这些参与烷烃降解的酶的基因位于两个基因簇alkBFGHJKL和alkST上 ,且此代谢途径受一个正反馈调节机制及两个不同的全局控制信号调控。其它可降解烷烃菌株的烷烃氧化基因与P .Putida中相应基因有较高的同源性。国内外的研究表明 ,alk基因可望应用于生物清污、微生物提高石油采收率及精细化工等诸多领域 。     

多溴联苯醚的微生物降解研究进展

多溴联苯醚(Polybrominated diphenyl ethers, PBDEs)作为一种阻燃剂在水体、土壤、沉积物和大气等自然环境中广泛存在。原本认为水溶性低而疏水性高的PBDEs 很难被生物所利用, 但近年研究表明微生物降解是PBDEs 降解的一种重要机制, 部分微生物能参与PBDEs 降解过程。在有氧条件下, 表面活性剂、共代谢基质和初始生长基质等都能影响微生物降解PBDEs; 双加氧酶在PBDEs 降解过程中起着关键作用。电子供体和助溶剂等则在微生物厌氧降解PBDEs 过程中发挥重要作用, 还原脱溴作用是微生物对PBDEs 进行厌氧降解的主要机制。筛选PBDEs 高效降解菌以及进一步揭示其降解机理对于修复PBDEs 污染问题具有重要的理论意义和现实意义。     

小叶章生态系统根际土壤微生物及CO2、CH4、N2O动态

研究了培养 4 5 d的小叶章根际土壤微生物和二氧化碳 ,甲烷及氧化亚氮产生与消耗之间的关系。结果表明好氧微生物与厌氧微生物的空间分布与甲烷 ,二氧化碳及氧化亚氮的产生和氧化有着密切的关系。好氧微生物与甲烷产生呈负相关 ,与二氧化碳和氧化亚氮的产生呈正相关关系。厌氧微生物与甲烷的产生呈正相关 ,与二氧化碳和氧化亚氮的产生呈负相关关系     

Potential for Aerobic and Anaerobic Biodegradation of Petroleum Hydrocarbons in Boreal Subsurface

We studied the role of aerobic and anaerobic petroleum hydrocarbon degradation at a boreal, light-weight fuel and lubrication oil contaminated site undergoing natural attenuation. At the site, anoxic conditions prevailed with high concentrations of CH4 (up to 25% v/v) and CO2 (up to 18% v/v) in the soil gas throughout the year. Subsurface samples were obtained mainly from the anoxic parts of the site and they represented both the unsaturated and saturated zone. The samples were incubated in microcosms at near in situ conditions (i.e. in situ temperature 8 degrees C, aerobic and anaerobic conditions, no nutrient amendments) resulting in the removal of mineral oil (as determined by gas chromatography) aerobically as well as anaerobically. In the aerobic microcosms on average 31% and 27% of the initial mineral oil was removed during a 3- and 4-month incubation, respectively. In the anaerobic microcosms, on average 44% and 15% of the initial mineral oil was removed during a 12- and 10-month anaerobic incubation, respectively, and e.g. n-alkanes from C11 to C15 were removed. A methane production rate of up to 2.5 microg CH4 h(-1) g(-1) dwt was recorded in these microcosms. In the aerobic as well as anaerobic microcosms, typically 90% of the mineral oil degraded belonged to the mineral oil fraction that eluted from the gas chromatograph after C10 and before C15, while 10% belonged to the fraction that eluted after C15 and before C40. Our results suggest that anaerobic petroleum hydrocarbon degradation, including n-alkane degradation, under methanogenic conditions plays a significant role in the natural attenuation in boreal conditions.     

Metabolism of alkylbenzenes, alkanes, and other hydrocarbons in anaerobic bacteria

Aromatic and aliphatic hydrocarbons are the main constituents of petroleum and its refined products. Whereas degradation of hydrocarbons by oxygen-respiring microorganisms has been known for about a century, utilization of hydrocarbons under anoxic conditions has been investigated only during the past decade. Diverse strains of anaerobic bacteria have been isolated that degrade toluene anaerobically, using nitrate, iron(III), or sulfate as electron acceptors. Also, other alkylbenzenes such as m-xylene or ethylbenzene are utilized by a number of strains. The capacity for anaerobic utilization of alkylbenzenes has been observed in members of the -, -, - and -subclasses of the Proteobacteria. Furthermore, denitrifying bacteria and sulfate-reducing bacteria with the capacity for anaerobic alkane degradation have been isolated, which are members of the - and -subclass, respectively. The mechanism of the activation of hydrocarbons as apolar molecules in the absence of oxygen is of particular interest.The biochemistry of anaerobic toluene degradation has been studied in detail. Toluene is activated by addition to fumarate to yield benzylsuccinate, which is then further metabolized via benzoyl-CoA. The toluene-activating enzyme presents a novel type of glycine radical protein. Another principle of anaerobic alkylbenzene activation has been observed in the anaerobic degradation of ethylbenzene. Ethylbenzene in denitrifying bacteria is dehydrogenated to 1-phenylethanol and further to acetophenone; the latter is also metabolized to benzoyl-CoA. Naphthalene is presumably activated under anoxic conditions by a carboxylation reaction. Investigations into the pathway of anaerobic alkane degradation are only at the beginning. The saturated hydrocarbons are mostlikely activated by addition of a carbon compound rather than by desaturation and hydration, as speculated about in some early studies. An anaerobic oxidation of methane with sulfate as electron acceptor has been documented in aquatic sediments. The process is assumed to involve a reversal of methanogenesis catalyzed by Archaea, and scavenge of an electron-carrying metabolite by sulfate-reducing bacteria. Among unsaturated non-aromatic hydrocarbons, anaerobic bacterial degradation has been demonstrated and investigated with n-alkenes, alkenoic terpenes and the alkyne, acetylene.     

生物可降解塑料在不同环境条件下的降解研究进展

当前社会塑料制品的使用需求持续增加,塑料垃圾处理压力不断增大,减缓塑料污染成为当务之急,生物可降解塑料因可在一定生物活性环境下较快降解而备受关注,具有广阔的应用前景。生物可降解塑料降解条件复杂,影响因素众多,对不同生物可降解塑料降解规律,降解微生物和功能酶的透彻掌握,是实现其全面利用和高效资源化处理处置的基础和前提。文章系统梳理了常见生物可降解塑料的种类、性能、优缺点和主要用途,全面综述了生物可降解塑料的降解机理、降解微生物和功能酶,以及生物可降解塑料在不同环境条件下的降解周期和程度,以期为生物可降解塑料的微生物降解研究提供借鉴,为生物可降解塑料废弃物的高效处理处置和彻底降解提供科学参考。     

红灯食烷菌(Alcanivorax hongdengensis)黄素结合单加氧酶(AlmA)的基因克隆及其烷烃诱导表达

【目的】研究海洋烷烃降解菌新种模式菌株Alcanivorax hongdengensis A-11-3降解长链烷烃的分子机制。【方法】PCR克隆编码黄素结合单加氧酶的基因序列,利用生物信息学软件对序列进行分析,运用RT-PCR和实时荧光定量PCR技术分析基因在不同烷烃诱导下的表达水平。【结果】从菌株A-11-3中克隆获得了两个黄素结合单加氧酶基因片段(almA1和almA2)。它们编码的氨基酸序列与菌株Acinetobacter sp.DSM17874的AlmA同源性分别为58.6%和53.2%。实时荧光定量PCR分析表明,almA1基因只在长链烷烃(C28-C32)的诱导下上调表达,而almA2基因中能在更宽范围的长链烷烃(C24-C34)和支链烷烃诱导下上调表达。两者均在C9-C22的烷烃诱导下没有上调表达。【结论】黄素结合单加氧酶可能是A-11-3降解长链烷烃和支链烷烃的关键酶。     

Evaluation of FKBP and DHFR based destabilizing domains in Saccharomyces cerevisiae

Two orthogonal destabilizing domains have been developed based on mutants of human FKBP12 as well as bacterial DHFR and these engineered domains have been used to control protein concentration in a variety of contexts in vitro and in vivo. FKBP12 based destabilizing domains cannot be rescued in the yeast Saccharomyces cerevisiae; ecDHFR based destabilizing domains are not degraded as efficiently in S. cerevisiae as in mammalian cells or Plasmodium, but provide a starting point for the development of domains with increased signal-to-noise in S. cerevisiae.