Bioremediation of polycyclic aromatic hydrocarbons: current knowledge and future directions

Polycyclic aromatic hydrocarbons (PAHs) are a class of organic compounds that have accumulated in the natural environment mainly as a result of anthropogenic activities such as the combustion of fossil fuels. Interest has surrounded the occurrence and distribution of PAHs for many decades due to their potentially harmful effects to human health. This concern has prompted researchers to address ways to detoxify/remove these organic compounds from the natural environment. Bioremediation is one approach that has been used to remediate contaminated land and waters, and promotes the natural attenuation of the contaminants using the in situ microbial community of the site. This review discusses the variety of fungi and bacteria that are capable of these transformations, describes the major aerobic and anaerobic breakdown pathways, and highlights some of the bioremediation technologies that are currently available. Copyright © 2005 Society of Chemical Industry     

Biodegradation of catechol by Pseudomonas fluorescens isolated from petroleum‐impacted soil

Bioremediation strategies have been applied to clean up petroleum hydrocarbon (PHC) impacted sites. Introducing PHC degrading microorganisms (bioaugmentation) and enhancing the in‐situ nutrients availability (biostimulation) are widely used strategies. These strategies can be combined to lead to a better bioremediation performance. In this work, Pseudomonas fluorescens was isolated from a PHC impacted site. Through a 2³ factorial design plan, the effect of various combinations of nitrate, sulphate, and phosphate ions on the PHC bioremediation performance by P. fluorescens was investigated using catechol, an essential metabolic intermediate of BTEX degradation, as the sole carbon source. The maximum specific catechol degradation rate was chosen as the response to evaluate the catechol bioremediation performance. The ANOVA results indicated that the presence of nitrate ions alone lowered the maximum specific catechol degradation rate, which can be explained by the accumulation of nitrites and ammonia during the denitrification process by P. fluorescens. It was noted that dosing sulphate ions alone did not affect the bioremediation performance, which indicates P. fluorescens can grow in a sulphur‐limited environment. In contrast, the presence of sulphate and nitrate ions together can lead to a higher specific catechol degradation rate. This may be caused by the presence of sulphate that can suppress the production of nitrites. The importance of phosphate ions on catechol biodegradation was investigated. The absence of phosphate led to incomplete biodegradation. Introducing phosphate ions can accelerate catechol degradation, which can be explained by the secretion of organic acids.     

城区内河水环境的生物治理——以池州市清溪河为例

对清溪河污染的治理,可以采用一系列理化的方法,但相比之下,利用生物治理不仅操作简便,成本低廉,而且能很好的修复水生生态系统的结构,达到良性循环的效果。驳岸的植物是一道屏障,能有效阻止和减少地表污染物进入水体,水中微生物将有机态的污染物转化为无机养份被植物吸收,植物为水中的微生物提供附着表面,而草食性鱼类能抑制植物的过渡生长,最终实现生态系统的重建与修复,使河道进入可持续发展的良性循环体系。     

利用基因工程菌修复富营养化水体

以徐州市黄河故道应用基因工程菌修复富营养化水体为研究对象，对水体中富营养化指标进行了测定，并对水体中生物生长变化情况进行了观察，试验和分析了基因工程菌中的消氮细菌及沉淀细菌对水体进行生物修复的作用及其效果，指出了存在的问题，为利用生物修复技术处理天然湖泊的富营养化提供了参考数据．     

Microbial Precipitation of Pb(II) with Wild Strains of Paraclostridium bifermentans and Klebsiella pneumoniae Isolated from an Industrially Obtained Microbial Consortium

The study focused on determining the microbial precipitation abilities of bacterial strains that were isolated from an industrially obtained Pb(II)-resistant microbial consortium. Previous research has demonstrated the effectiveness of the consortium on the bioprecipitation and adsorption of Pb(II) from solution. The bioremediation of Pb(II) using microbial precipitation provides an alternative option for Pb(II) removal from wastewater. Both strains, Klebsiella pneumoniae and Paraclostridium bifermentans, were successfully isolated from the consortium obtained from a battery recycling plant in South Africa. The experiments were conducted over both 30 h and 5 d, providing insight into the short- and long-term precipitation abilities of the bacteria. Various initial concentrations of Pb(II) were investigated, and it was found that P. bifermentans was able to remove 83.8% of Pb(II) from solution with an initial Pb(II) concentration of 80 mg L−1, while K. pneumoniae was able to remove 100% of Pb(II) with the same initial Pb(II) concentration after approximately 5 d. With the same initial Pb(II) concentration, P. bifermentans was able to remove 86.1% of Pb(II) from solution, and K. pneumoniae was able to remove 91.1% of Pb(II) from solution after 30 h. The identities of the precipitates obtained for each strain vary, with PbS and Pb0 being the main species precipitated by P. bifermentans and PbO with either PbCl or Pb3(PO4)2 precipitated by K. pneumoniae. Various factors were investigated in each experiment, such as metabolic activity, nitrate concentration, residual Pb(II) concentration, extracellular and intracellular Pb(II) concentration and the precipitate identity. These factors provide a greater understanding of the mechanisms utilised by the bacteria in the bioprecipitation and adsorption of Pb(II). These results can be used as a step towards applying the process on an industrial scale.     

石油污染土壤生物修复与多技术联合修复策略研究进展及工程化应用

在传统石油污染土壤修复方法的基础上,综述了生物修复联合多技术修复石油污染土壤的方法、原理、研究现状及应用。并对如何更好地将生物修复与多技术相结合,提高修复效率和改善修复产物提出了展望,对采用以生物修复为核心的多技术联合修复策略在油田污染治理和生态环境恢复方面具有指导意义,以期为提高石油污染土壤修复效果提供依据。     

细菌诱导矿化保护历史建筑遗产的机理及效果

为了研究细菌诱导碳酸钙在大理石、混凝土基材表层矿化沉积形成的人工层对基材加固保护的机理及性能,用X射线衍射、扫描电镜、压汞仪及超声波研究分析了矿化晶体物相,矿化层生长,沉积晶体对基材孔隙的影响以及矿化层黏结与保护效果.结果表明:矿化晶体为方解石和球文石;Ca2+源影响碳酸钙矿化沉积晶相,细菌在晶体矿化沉积过程中充当成核位点,且晶体均匀生长在基材表面;沉积致使试样孔隙率减少,但对孔隙分布无显著影响;矿化层与基材可以形成有效黏结.     

Deposition of Lead Phosphate by Lead-Tolerant Bacteria Isolated from Fresh Water near an Abandoned Mine

Specialist bacteria can synthesize nanoparticles from various metal ions in solution. Metal recovery with high efficiency can be achieved by metal-tolerant microorganisms that proliferate in a concentrated metal solution. In this study, we isolated bacteria (Pseudomonas sp. strain KKY-29) from a bacterial library collected from water near an abandoned mine in Komatsu City, Ishikawa Prefecture, Japan. KKY-29 was maintained in nutrient medium with lead acetate and synthesized hydrocerussite and pyromorphite nanoparticles inside the cell; KKY-29 also survived nanoparticle synthesis. Quantitative PCR analysis of genes related to phosphate metabolism showed that KKY-29 decomposed organic phosphorus to synthesize lead phosphate. KKY-29 also deposited various metal ions and synthesized metal nanoparticles when incubated in various metal salt solutions other than lead. The present study considers the development of biotechnology to recover lead as an economically valuable material.     

分子生物学技术在土壤生物修复中的应用及展望

综述了分子生物学技术包括环境微生物群落降解基因分析、16S rRNA序列分析技术以及荧光原位杂交技术在生物修复技术中跟踪污染土壤中降解微生物行为、监测降解基因和微生物群落变化,揭示了其中的分子机制的应用现状,对各项技术应用中需要注意的问题进行了讨论并对其发展前景进行了展望。     

受污染含水层抽水——处理最优化及对地下水污染生物修复的基本认识

本文讨论了修复受污染含水层的抽水———处理技术的最优化问题,提出建立抽水———处理最优化模型时应注意的三个要素,以确定含水层修复的最佳战略。认为抽水———处理技术是一种好方法。涉及与地下水污染有关的问题,需要能够模拟在地下进行的生物修复和污染物运移的计算机模型。近年来,研发了许多数字程序来认识生物降解/生物变换过程。可是,对这种生物修复系统进行数值模拟,总是需要做出确实的计算上的努力。如果有一些恰当的解析解可作为适宜应用的筛选手段,则便于在详细研究以前进行生物修复评价。本文提出了模拟生物修复和有反应运移的解析模型的文献评论。