Laboratory of Fungal Biodiversity, Department of Environmental Biology, Sapienza University of Rome, Rome, Italy
Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria (CREA), Centro di Ricerca Agricoltura e Ambiente, Rome, Italy.
Appl Environ Microbiol. 2019 Oct 16;85(21). doi: 10.1128/AEM.01720-19. Print 2019 Nov 1.
DDT (dichlorodiphenyltrichloroethane) was used worldwide as an organochlorine insecticide to control agricultural pests and vectors of several insect-borne human diseases. It was banned in most industrialized countries; however, due to its persistence in the environment, DDT residues remain in environmental compartments, becoming long-term sources of exposure. To identify and select fungal species suitable for bioremediation of DDT-contaminated sites, soil samples were collected from DDT-contaminated agricultural soils in Poland, and 38 fungal taxa among 18 genera were isolated. Two of them, FBL 587 and FBL 578, were tested for tolerance in the presence of 1-mg liter DDT concentration by using two indices based on fungal growth rate and biomass production (the tolerance indices Rt:Rc and TI), showing a clear tolerance to DDT. The two selected strains were studied to evaluate catabolic versatility on 95 carbon sources with or without DDT by using the Phenotype MicroArray system and to investigate the induced oxidative stress responses. The two strains were able to use most of the substrates provided, resulting in both high metabolic versatility and ecological functionality in the use of carbon sources, despite the presence of DDT. The activation of specific metabolic responses with species-dependent antioxidant enzymes to cope with the induced chemical stress has been hypothesized, since the presence of DDT promoted a higher formation of reactive oxygen species in fungal cells than the controls. The tested fungi represent attractive potential candidates for bioremediation of DDT-contaminated soil and are worthy of further investigations. The spread and environmental accumulation of DDT over the years represent not only a threat to human health and ecological security but also a major challenge because of the complex chemical processes and technologies required for remediation. Saprotrophic fungi, isolated from contaminated sites, hold promise for their bioremediation potential toward toxic organic compounds, since they might provide an environment-friendly solution to contamination. Once we verified the high tolerance of autochthonous fungal strains to high concentrations of DDT, we showed how fungi from different phyla demonstrate a high metabolic versatility in the presence of DDT. The isolates showed the singular ability to keep their functionality, despite the DDT-induced production of reactive oxygen species.
滴滴涕（DDT）曾作为一种有机氯杀虫剂在全球范围内用于防治农业害虫和几种虫媒传染病的病媒。它已在大多数工业化国家被禁用；然而，由于其在环境中的持久性，滴滴涕残留仍存在于环境介质中，成为长期暴露的来源。为了鉴定和选择适合用于修复滴滴涕污染场地的真菌物种，我们从波兰受滴滴涕污染的农业土壤中采集了土壤样本，并从中分离出了 18 属中的 38 种真菌。其中两种，FBL 587 和 FBL 578，通过使用基于真菌生长速率和生物量产生的两个指数（耐度指数 Rt:Rc 和 TI），在 1 毫克升滴滴涕浓度下进行了耐受力测试，表现出对滴滴涕的明显耐受力。选择这两种菌株，通过使用 Phenotype MicroArray 系统研究它们在有或没有滴滴涕的情况下对 95 种碳源的代谢多样性，并研究其诱导的氧化应激反应。这两种菌株能够利用所提供的大部分底物，从而在使用碳源方面表现出高代谢多样性和生态功能，尽管存在滴滴涕。由于滴滴涕的存在促进了真菌细胞中活性氧的形成，因此假设了物种依赖的抗氧化酶参与了特定代谢反应的激活，以应对诱导的化学应激。测试的真菌代表了用于修复滴滴涕污染土壤的有吸引力的潜在候选物，值得进一步研究。滴滴涕在多年间的传播和环境积累不仅对人类健康和生态安全构成威胁，而且由于需要复杂的化学过程和技术来进行修复，这也是一个主要挑战。从污染地点分离出的腐生真菌具有修复有毒有机化合物的潜力，因为它们可能为污染提供一种环境友好的解决方案。一旦我们验证了土著真菌菌株对高浓度滴滴涕的高耐受力，我们就展示了来自不同门的真菌在滴滴涕存在下表现出的高代谢多样性。这些分离株表现出了一种独特的能力，即在滴滴涕诱导产生活性氧的情况下保持其功能。
