Chemistry Department and ICAAM, School of Science and Technology, University of Évora, 7000-671 Évora, Portugal.
Arch Environ Contam Toxicol. 2013 Jul;65(1):67-77. doi: 10.1007/s00244-013-9877-5. Epub 2013 Feb 22.
Degradation of xenobiotics by microbial populations is a potential method to enhance the effectiveness of ex situ or in situ bioremediation. The purpose of this study was to evaluate the impact of repeated metalaxyl and folpet treatments on soil microbial communities and to select soil fungal strains able to degrade these fungicides. Results showed enhanced degradation of metalaxyl and folpet in vineyards soils submitted to repeated treatments with these fungicides. Indeed, the greatest degradation ability was observed in vineyard soil samples submitted to greater numbers of treatments. Respiration activities, as determined in the presence of selective antibiotics in soil suspensions amended with metalaxyl and folpet, showed that the fungal population was the microbiota community most active in the degradation process. Batch cultures performed with a progressive increase of fungicide concentrations allowed the selection of five tolerant fungal strains: Penicillium sp. 1 and Penicillium sp. 2, mycelia sterila 1 and 3, and Rhizopus stolonifer. Among these strains, mycelium sterila 3 and R. stolonifer presented only in vineyard soils treated with repeated application of these fungicides and showed tolerance >1,000 mg l(-1) against commercial formulations of metalaxyl (10 %) plus folpet (40 %). Using specific methods for inducing sporulation, mycelium sterila 3 was identified as Gongronella sp. Because this fungus is rare, it was compared using csM13-polymerase chain reaction (PCR) with the two known species, Gongronella butleri and G. lacrispora. The high tolerance to metalaxyl and folpet shown by Gongronella sp. and R. stolonifer might be correlated with their degradation ability. Our results point out that selected strains have potential for the bioremediation of metalaxyl and folpet in polluted soil sites.
微生物种群对异生物质的降解是增强异位或原位生物修复效果的一种潜在方法。本研究旨在评估重复使用金属草净和灭菌丹对土壤微生物群落的影响，并筛选能够降解这些杀菌剂的土壤真菌菌株。结果表明，在重复使用这些杀菌剂处理的葡萄园土壤中，金属草净和灭菌丹的降解能力得到了增强。事实上，在接受更多处理的葡萄园土壤样本中，观察到了最大的降解能力。在添加金属草净和灭菌丹的土壤悬浮液中，使用选择性抗生素测定的呼吸活性表明，真菌种群是降解过程中最活跃的微生物群落。通过分批培养，在逐步增加杀菌剂浓度的条件下，筛选出了 5 株具有耐受性的真菌菌株：青霉 1 号和青霉 2 号、无菌菌丝体 1 号和 3 号，以及根霉。在这些菌株中，无菌菌丝体 3 号仅存在于经过重复使用这些杀菌剂处理的葡萄园土壤中，对商业配方的金属草净（10%）+灭菌丹（40%）的耐受浓度>1000mg/L。使用诱导孢子形成的特定方法，无菌菌丝体 3 号被鉴定为 Gongronella sp. 由于这种真菌较为罕见，因此使用 csM13-聚合酶链反应（PCR）与两种已知的 Gongronella butleri 和 G. lacrispora 进行了比较。Gongronella sp.和 R. stolonifer 对金属草净和灭菌丹的高耐受性可能与其降解能力有关。我们的研究结果表明，所选菌株具有在污染土壤中进行金属草净和灭菌丹生物修复的潜力。
