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。     

蔗糖酯和鼠李糖脂对水果贮藏保鲜的作用

蔗糖脂肪酸酯和生物表面活性剂鼠李糖脂经复配后的保鲜剂对苹果、梨和芦柑具有明显降低腐烂率、干耗率和呼吸速率及延长贮藏期的作用,果实的硬度也较好。     

微生物修复石油烃土壤污染技术研究进展

随着人民生活水平的提高,环境保护问题愈发受到人们重视。其中石油烃的土壤污染因其持续时间长、污染去除难度大而受到广泛关注。在各类修复技术中,原位微生物修复强化技术因其成本较低、环境影响小、无二次污染、可原位修复的特点成为了当前的技术热门。文中综述了生物投加法、生物刺激法、联合修复法等原位微生物修复技术,并介绍了一些典型工程案例,为原位微生物修复强化技术的选择及工程应用提供了参考,并对未来原位微生物修复强化技术的研究重点进行了展望。     

鼠李糖脂粗提物对植物病原真菌的抑菌作用

生物表面活性剂对植物真菌病害的防控效应受到广泛关注.鼠李糖脂是由铜绿假单胞菌合成的一种阴离子生物表面活性剂,作为植物病原真菌抑制剂的开发潜力较大,但目前对其抑菌谱和抑菌能力还缺乏全面的评价.本研究收集了 29种常见的植物病原真菌,依据真菌Ainsworth系统分类法评价不同分类地位的病原真菌对鼠李糖脂抑制作用的敏感性....     

基因工程微生物合成鼠李糖脂表面活性剂的研究进展

鼠李糖脂是一类重要的生物表面活性剂。相比于化学合成的表面活性剂,其具有更优秀的理化性质及环境友好等特点,被广泛应用于微生物采油、环境污染修复等工程中。目前,鼠李糖脂的工业生产主要采用铜绿假单胞菌这一具有致病性的天然合成菌株,与此同时,受菌株遗传背景的限制,优化发酵过程等方法在产量提升方面遇到了一些瓶颈问题。利用基因工程方法对菌株进行改良有望进一步提高鼠李糖脂生产的安全性、产量、产物性能等多项指标,因此受到了越来越广泛的关注。本文综述了近年来利用基因工程方法优化鼠李糖脂生物合成的最新进展,讨论了异源合成、代谢通路改造、基因表达优化、蛋白质工程、底盘工程等多种策略的应用,并展望了一系列可行的研究方向。     

鼠李糖脂生物表面活性剂的研究进展

鼠李糖脂是一种重要的生物表面活性剂。综述了鼠李糖脂生物表面活性剂的化学结构、特性、生理学功能及其发酵生产,特别讨论了利用廉价原料——工农业的废物,如植物油废渣等来生产鼠李糖脂,其不仅可降低生产成本,还能减少工农业废渣对环境的污染,降低其处理费用。     

鼠李糖脂快速定量分析方法及其影响因素研究

为探寻简单、快速的由铜绿假单胞菌生产鼠李糖脂的定量分析方法,对比分析了葸酮—硫酸法、L-半胱氨酸-硫酸法、苯酚硫酸法及其影响因素。结果显示,蒽酮硫酸法优于其它两种方法,并得出了其最佳测试条件。发酵液中剩余的葡萄糖、上清液对鼠李糖脂定量分析的影响可以忽略,菌体和中层杂质对鼠李糖脂的定量分析有一定程度的影响。因而,分析时要去除菌体。而中层杂质对定量分析的影响可以通过制备含中层杂质的鼠李糖溶液标准曲线而消除。     

废弃食用油脂生物合成鼠李糖脂研究进展

碳源的成本过高限制了鼠李糖脂的工业化生产及应用,废弃食用油脂作为一种廉价易得的碳源,越来越多的研究者开始关注用它发酵生产鼠李糖脂.废弃食用油脂的种类、投加量对鼠李糖脂的产量、结构、性质均会产生影响,目前研究中用废弃食用油脂作碳源,鼠李糖脂产量最高可达24.61g/L、表面张力最低达到24mN/m、产物CMC最低可达40.19mg/L.此外,本文还总结了菌株、氮源、微量元素、pH、溶氧及培养方式等因素对废弃食用油脂生产鼠李糖脂的影响,并展望了利用废弃食用油脂生产鼠李糖脂实现产业化的重点研究方向.     

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。     

Effect of Estuarine Sediment pH and Oxidation-Reduction Potential on Microbial Hydrocarbon Degradation

Microbial mineralization rates of two petroleum hydrocarbons, as affected by pH and oxidation-reduction potential, were determined in a Barataria Bay, Louisiana, sediment using ¹⁴C-labeled hydrocarbons. Hydrocarbon mineralization rates were inferred from the activity of respired ¹⁴CO₂. Sediment pH and oxidation-reduction potential were important factors in governing the population of hydrocarbon-degrading microorganisms in the sediment and subsequent mineralization rates. Highest mineralization rates occurred at pH 8.0, and the lowest occurred at pH 5.0. At all pH levels mineralization decreased with decreasing oxidation-reduction potential (i.e., increasing sediment anaerobiosis). Generally, mineralization rates for octadecane were greater than those for naphthalene. Aerobic microorganisms in the oxidized sediment were more capable of degrading hydrocarbons than anaerobic microorganisms in reduced sediment of the same pH.     

Microbial Degradation of n-Alkyl Tetrahydrothiophenes Found in Petroleum

[This corrects the article on p. 1245 in vol. 54.].     

石油污染海域的微生物群落及烃的降解

目前世界海洋石油污染问题已经严重威胁到海洋生态环境的安全,生物修复是一种处理石油污染的新方法。综述了海洋环境中烃降解微生物生态学方面的一些研究进展,包括探测未培养细菌的新方法、新的分离方法及主要的烃降解菌株的特性,以便努力改进现有分离石油降解菌及石油乳化细菌的方法,同时发现对于石油降解有益的新菌种。     

Degradation of Petroleum Oils by a Selected Microbial Association

A series of microbial associations capable of the biodegradation of various petroleum oils, emulsols, and crude oil were obtained by selection during periodic or continuous cultivation. Formation of the associations and oil-product degradation occurred most efficiently during aerobic flow cultivation. Under these conditions, oils were degraded by 92% on average. The microbial degradation of a petroleum oil depended on its brand, concentration, emulsification, and aeration.     

Hydrocarbon Leaching, Microbial Population, and Plant Growth in Soil Amended with Petroleum

Two samples of oily waste organics (OWO) from petroleum wells were added to heath soils from Tierra del Fuego, Argentina, and the effects on hydrocarbon leaching, microbial population, and plant growth were studied. These mixtures and a control soil were subjected to four deionized water leachates. For each leachate, total petroleum hydrocarbons (TPH), aliphatic hydrocarbons (ALH), aromatic hydrocarbons (ARH) with three or fewer rings, ARH with more than three rings, and oil and grease (O&G) were measured. After leaching, six Dactylis glomerata L. plants were grown in each soil column. Plant growth and the total number of aerobic and nitrifier microorganisms were measured in soil. The 10% OWO sample increased the TPH in the leachate, but the 1% sample did not. The ALH, ARH, and O&G of each leachate followed patterns similar to that for TPH. Plant growth diminished and the total number of aerobic and nitrifier microorganisms decreased with increasing OWO, especially when the OWO was from a fresh residue rather than an aged residue. The greater inhibitive effect of fresh residue on plant growth was attributed to a higher concentration of light hydrocarbons, which are more toxic than heavy hydrocarbons. For soil with 1% OWO added, the TPH and other organics did not differ from the control soil. This result, combined with the 10-year average annual rainfall and the water table elevation at the site, suggests that the risk of contaminating the water table is relatively low. Thus, a 1% addition of OWO in soil would be appropriate to use in landfarming of OWO.     

Impact of Surfactant on Configuration of Petroleum Hydrocarbon Lens

A laboratory-scale physical model was constructed for visual observation of the basic 2-D flow characteristics of a gasoline spill through an unconfined aquifer and the subsequent treatment with a surfactant. The model consists of a parallel-plate glass tank (1?m×1?m×5?cm) packed with Ottawa sand. Gasoline was released from a point source in the vadose zone. As the specific gravity of gasoline is less than one (LNAPL), it pooled above the water saturated pores of the tension saturated region of water. Beyond the lens of gasoline, the height of the capillary fringe was reduced due to capillary pollution. The gasoline lens was then treated with an aqueous phase surfactant solution of 2% dodecyl benzene sulfonate (anionic) and 2% polyethoxylate nonyl phenol (nonionic). This surfactant solution reduced the interfacial tension between the gasoline and the aqueous phase by an order of magnitude. The surfactant solution was released from the same point source in the vadose zone as the gasoline. As a result, the location and geometry of the gasoline lens and the polluted capillary fringe were significantly altered. These changes were investigated using vertical equilibrium models, the capillary number, the buoyancy number and the total trapping number to evaluate the approach of pretreatment as a potential remediation strategy.     

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。     

Effect of Photosynthetic Bacteria and Compost on Degradation of Petroleum Products in Soil

Addition of diesel fuel and waste engine oil to soil was found to stimulate hydrocarbon-oxidizing microorganisms. Corynebacteria constitute a large group of hydrocarbon-oxidizing microorganisms. Addition of a liquid culture of photosynthetic bacteria to soil facilitates degradation of petroleum products and also stimulates growth of hydrocarbon-oxidizing microorganisms. Combined addition of photosynthetic bacteria and compost to soil polluted with petroleum products produces a greater increase in the number of hydrocarbon-oxidizing bacteria and substantially augments the rate of pollutant degradation.