Department of Soil Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.
Department of Soil Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.
Microb Pathog. 2020 Dec;149:104473. doi: 10.1016/j.micpath.2020.104473. Epub 2020 Sep 8.
Triclosan (TCS) is an extensively used antibacterial agent which has been frequently detected in different environmental compartments. Because of TCS inhibition effect on vast majority of bacterial species, it is important to explore fungal species and their involved enzymes in TCS biodegradation. The aim of this study was to compare the potential of two white rot fungi Pleurotus ostreatus and Trametes versicolor for TCS biodegradation through the whole cell culture of fungi in an aqueous culture medium. Additionally, the changes in ligninolytic enzyme activities and possible correlations and contributions of degradative enzymes during TCS biodegradation process were monitored.
This study was carried out using a factorial experiment with a completely randomized design in three replications. factorial design in The experimental factors included: two white rot fungi Pleurotus ostreatus and Trametes versicolor and uninoculated controls which were subjected to five levels of TCS concentrations (0, 5, 10, 20, 30 and 50 μg mL) to assess ligninolytic enzymatic activity during biodegradation of TCS. Samples were harvested periodically at three time intervals (4, 7 and 10 days). An AB SCIEX 3200 QTRAP LC-MS/MS system was used in order to analyze the biodegradation of TCS in liquid medium.
Results suggested that the two white rot fungi responded differently when exposed to the different concentrations of TCS. In general, P. ostreatus exhibited more potential and ligninolytic enzymatic activity compared to T. versicolor. LC-MS/MS analyses also showed that P. ostreatus degraded TCS with higher efficiency compared to T. versicolor. In addition, almost all P. ostreatus biodegradation activity was completed within the first day of sampling. Contrasting, less efficient degradation was observed by T. versicolor, reaching around 88% of TCS biodegradation at concentration of 20 μg mLafter 10 days. At higher TCS concentrations (≥30 μg mL), the growth of T. versicolor severely inhibited and led to a drop in enzymatic activity and biodegradation. Furthermore, laccase and manganese peroxidase (MnP) were determined as more involved enzymes which significantly correlated to TCS biodegradation by T. versicolor and P. ostreatus, respectively.
P. ostreatus might be considered as efficient fungus in biodegradation of high amount of TCS in environmental matrices. The results of the present study might provide insights for future investigations on potential of fungi for applications in bioaugmentation-based strategies to remove TCS from wastewater and activated sludge.
三氯生（TCS）是一种广泛使用的抗菌剂，已在不同的环境介质中频繁检出。由于 TCS 对绝大多数细菌物种都有抑制作用，因此探索真菌物种及其参与 TCS 生物降解的相关酶类至关重要。本研究旨在通过真菌的整个细胞培养，在水相培养基中比较两种白腐真菌糙皮侧耳（Pleurotus ostreatus）和栓菌（Trametes versicolor）对 TCS 生物降解的潜力。此外，监测木质素降解酶活性的变化，以及在 TCS 生物降解过程中可能存在的相关性和降解酶的贡献。
本研究采用完全随机设计的析因实验，在三个重复中进行。实验因素包括：两种白腐真菌糙皮侧耳（Pleurotus ostreatus）和栓菌（Trametes versicolor）以及未接种对照，它们分别接受五个 TCS 浓度水平（0、5、10、20、30 和 50μgmL）的处理，以评估 TCS 生物降解过程中木质素降解酶的活性。样品在三个时间间隔（4、7 和 10 天）定期采集。采用 AB SCIEX 3200 QTRAP LC-MS/MS 系统对液体培养基中 TCS 的生物降解进行分析。
结果表明，两种白腐真菌在暴露于不同浓度的 TCS 时表现出不同的反应。一般来说，糙皮侧耳（P. ostreatus）比栓菌（T. versicolor）表现出更大的潜力和木质素降解酶活性。LC-MS/MS 分析还表明，糙皮侧耳（P. ostreatus）比栓菌（T. versicolor）更有效地降解 TCS。此外，糙皮侧耳（P. ostreatus）的几乎所有 TCS 生物降解活性都在采样的第一天内完成。相比之下，栓菌（T. versicolor）的降解效率较低，在 10 天内，TCS 浓度为 20μgmL时，TCS 的生物降解率约为 88%。在较高的 TCS 浓度（≥30μgmL）下，栓菌（T. versicolor）的生长受到严重抑制，导致酶活性和生物降解下降。此外，漆酶和锰过氧化物酶（MnP）被确定为与 T. versicolor 和 P. ostreatus 的 TCS 生物降解显著相关的更相关酶类。
糙皮侧耳（P. ostreatus）可被视为在环境基质中高效降解大量 TCS 的真菌。本研究结果可为未来研究真菌在基于生物增强的策略中的应用提供见解，以去除废水中和活性污泥中的 TCS。
