Department of Plant Biology, University of Turin, viale Mattioli 25, 10125 Turin, Italy.
Microb Cell Fact. 2009 Jan 12;8:5. doi: 10.1186/1475-2859-8-5.
Polychlorinated biphenyls (PCBs) are widespread toxic pollutants. Bioremediation might be an effective, cost competitive and environment-friendly solution for remediating environmental matrices contaminated by PCBs but it is still unsatisfactory, mostly for the limited biodegradation potential of bacteria involved in the processes. Very little is known about mitosporic fungi potential in PCB bioremediation and their occurrence in actual site historically contaminated soils. In the present study, we characterised the native mycoflora of an aged dump site soil contaminated by about 0.9 g kg-1 of Aroclor 1260 PCBs and its changing after aerobic biotreatment with a commercial complex source of bacteria and fungi. Fungi isolated from the soil resulting from 120 days of treatment were screened for their ability to adsorb or metabolise 3 target PCBs.
The original contaminated soil contained low loads of few fungal species mostly belonging to the Scedosporium, Penicillium and Aspergillus genera. The fungal load and biodiversity generally decreased throughout the aerobic treatment. None of the 21 strains isolated from the treated soil were able to grow on biphenyl (200 mg L-1) or a mixture of 2-chlorobiphenyl, 4,4'-dichlorobiphenyl and 2,2',5,5'-tetrachlorobiphenyl (20 mg L-1 each) as sole carbon sources. However, 16 of them grew in a mineral medium containing the same PCBs mixture and glucose (10 g L-1). Five of the 6 isolates, which displayed the faster and more extensive growth under the latter conditions, were found to degrade the 3 PCBs apparently without the involvement of ligninolytic enzymes; they were identified as Penicillium chrysogenum, Scedosporium apiospermum, Penicillium digitatum and Fusarium solani. They are the first PCB degrading strains of such species reported so far in the literature.
The native mycoflora of the actual site aged heavily contaminated soil was mainly constituted by genera often reported as able to biodegrade organopollutants. It was generally remarkably reduced after the biotreatment, which however resulted in the selection of few mitosporic fungal species able to biodegrade PCBs. This is the first study in which an extensive characterisation of the cultivable indigenous mycoflora of an actual site aged PCB contaminated soil, as well as its changes upon soil bioremediation treatment, was conducted. Moreover, this is the first paper in which 5 strains ascribable to 4 mitosporic species able to biodegrade PCB are reported in the literature.
多氯联苯（PCBs）是广泛存在的有毒污染物。生物修复可能是一种有效、具有成本竞争力和环境友好的方法，可用于修复被 PCB 污染的环境基质，但它仍然不尽如人意，主要是因为参与该过程的细菌的生物降解潜力有限。关于有丝分裂真菌在 PCB 生物修复中的潜力以及它们在历史上受污染的实际地点土壤中的存在，人们知之甚少。在本研究中，我们对一个老化垃圾场土壤的本土真菌区系进行了特征描述，该土壤受约 0.9 g kg-1 的 Aroclor 1260 PCB 污染，并在有氧生物处理后对其进行了研究，该生物处理使用了一种商业复合细菌和真菌源。从处理 120 天后的土壤中分离出的真菌被筛选出其吸附或代谢 3 种目标 PCB 的能力。
原始污染土壤中含有低负荷的少数真菌物种，主要属于枝孢菌属、青霉属和曲霉属。真菌负荷和生物多样性在整个有氧处理过程中普遍下降。从处理过的土壤中分离出的 21 株菌中，没有一株能够在联苯（200mg/L）或 2-氯联苯、4,4'-二氯联苯和 2,2',5,5'-四氯联苯混合物（每种 20mg/L）上生长作为唯一的碳源。然而，其中 16 株在含有相同 PCB 混合物和葡萄糖（10g/L）的矿物培养基中生长。在后者条件下生长更快、更广泛的 6 个分离株中的 5 个被发现可明显降解 3 种 PCB，而不涉及木质素降解酶；它们被鉴定为产黄青霉、枝顶孢属、桔青霉和茄病镰刀菌。它们是迄今为止文献中首次报道的此类物种的 PCB 降解菌株。
实际受严重污染土壤的本土真菌区系主要由常被报道能够生物降解有机污染物的属组成。在生物处理后，它通常显著减少，但这导致了少数有丝分裂真菌物种的选择，这些物种能够生物降解 PCBs。这是首次对实际受 PCB 污染土壤的可培养本土真菌区系进行广泛特征描述，以及在土壤生物修复处理后其变化的研究。此外，这是首次有 5 株可归属于 4 种有丝分裂种的 PCB 降解菌株的论文在文献中报道。
