多环芳烃降解菌及其应用研究进展

Research progress on polycyclic aromatic hydrocarbons degrading bacteria and their applications

  • 摘要: 多环芳烃(PAHs)在环境中分布广泛,且具有生态和环境毒理效应,因此对PAHs污染场地的治理和修复备受关注。生物降解是去除PAHs的重要技术之一,但存在降解效率低、周期长等局限性。归纳了PAHs常见降解菌及其主要降解机制,探讨了PAHs降解菌在实际污染场地应用的研究进展与不足。结果表明:PAHs降解菌株主要包括不动杆菌属(Acinetobacter)、分枝杆菌属(Mycobacterium)和假单胞菌属(Pseudomonas),白腐真菌是常见的降解菌;相比单一菌株,复合菌群对PAHs的降解能力更强。在降解菌株降解基因(如nah基因簇)编码酶的作用下,萘、菲和芘等PAHs发生开环并逐步氧化,最终通过水杨酸或邻苯二甲酸途径进入三羧酸循环实现完全降解;而苯并a芘降解过程中会产生包括醇、醛、酸类中间产物,其完全降解机理仍有待研究。目前大部分针对PAHs降解菌的研究局限于实验室条件,缺少实际PAHs污染场地降解性能的验证;实际应用中,降解菌活性和PAHs的去除受温度、pH、氧气浓度和土壤有机质含量等环境因子的影响。PAHs降解菌的应用实例包括采用生物刺激和(或)生物强化的方式以促进PAHs污染场地的修复。然而,生物降解在实际应用中仍需克服降解菌失活、技术耦合困难、环境风险和成本高等限制因素。未来研究主要包括复合污染和土著菌共存条件下PAHs生物降解机制研究、降解菌生理特性调控和新型强化材料的开发;此外,应加强降解菌在实际污染场地应用的推广,以实现对PAHs污染的高效、经济、可持续治理。

     

    Abstract: Polycyclic aromatic hydrocarbons (PAHs) are a group of pollutants widely distributed in the environment and have ecological and environmental toxicity effects. Therefore, the remediation and restoration of PAHs-contaminated sites have received significant attention. Biodegradation is one of the essential technologies for removing PAHs; however, it still faces limitations such as low degradation efficiency and long degradation periods. The common PAHs-degrading bacteria and their degradation mechanisms were summarized, focusing on discussing the research progress and limitations of applying them to real contaminated sites. The results showed that PAHs-degrading bacteria mainly included genus Acinetobacter, Mycobacterium, and Pseudomonas. White-rot fungi were common fungi that degraded PAHs. Compared to individual strains, bacterial consortia exhibited superior PAH degradation capability. For PAHs such as naphthalene, phenanthrene and pyrene, the degradation process involved ring opening catalyzed by enzymes encoded by PAHs degradation genes (e.g., nah gene cluster), followed by stepwise oxidation, ultimately leading to complete degradation through the salicylic acid or phthalic acid pathway entering the tricarboxylic acid cycle. The degradation of benzoapyrene produced intermediate products, including alcohols, aldehydes, and acids. However, its complete degradation pathway was yet to be identified. Studies on PAHs degradation bacteria were mainly confined to laboratory conditions, and there was a lack of verification in real contaminated soils. In application, the activity of degrading bacteria and the efficiency of PAHs removal were influenced by various environmental factors, including temperature, pH, oxygen levels, and soil organic matter content. In addition, some cases utilized biological stimulation and/or bioaugmentation to significantly improve the bioremediation of PAH-contaminated sites. Nevertheless, the application must overcome multiple limiting factors, including reduced degrading bacteria activity, failed integration with multiple technologies, and high environmental risks and costs. Further researches should include the mechanisms of PAHs biodegradation under conditions with combined pollution and the presence of indigenous microorganisms, the regulation of physiological characteristics of degrading bacteria, and the development of novel materials. Furthermore, promoting the application of PAHs-degrading bacteria in real contaminated sites should be strengthened to achieve efficient, economical, and sustainable control of PAHs contamination

     

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