Exploring the Diversity and Aromatic Hydrocarbon Degrading Potential of Epiphytic Fungi on Hornbeams from Chronically Polluted Areas.

Valeria Imperato,Jaco Vangronsveld,Anneleen Thoonen,Francois Rineau,Sofie Thijs,Miguel Portillo-Estrada,Łukasz Kowalkowski,Stanislaw W Gawronski,Anabel Saran

doi:10.3390/jof7110972

Abstract

Plants can ‘catch’ and mitigate airborne pollutants and are assisted by fungi inhabiting their leaves. The structure and function of the fungal communities inhabiting the phyllosphere of hornbeam trees growing in two chronically polluted areas, the oilfield of Bóbrka and the city center of Warsaw, were compared to the ones growing in one nature reserve, the Białowieża National Park. Fungi were isolated and characterized both phylogenetically and functionally for their potential role in air pollution mitigation. Both culture-dependent (e.g., enzyme assays and tolerance tests) and culture-independent methods (e.g., ITS and shotgun sequencings) were used. Furthermore, the degradation potential of the fungi was assessed by gas chromatography mass spectrometry (GC-MS). Shotgun sequencing showed that the phyllosphere fungal communities were dominated by fungi belonging to the phylum Ascomycota. Aureobasidium was the only genus detected at the three locations with a relative abundance ≥1.0%. Among the cultivated epiphytic fungi from Bóbrka, Fusarium sporotrichioides AT11, Phoma herbarum AT15, and Lophiostoma sp. AT37 showed in vitro aromatic hydrocarbon degradation potential with laccase activities of 1.24, 3.62, and 7.2 μU L−1, respectively, and peroxidase enzymes with activities of 3.46, 2.28, and 7.49 μU L−1, respectively. Furthermore, Fusarium sporotrichioides AT11 and Phoma herbarum AT15 tolerated exposure to airborne naphthalene and benzene. Lophiostoma sp. AT37 was the most tolerant to exposure to these pollutants, in line with being the best potential aromatic hydrocarbon degrader isolated in this study.

Highlights

Outdoor air pollution is an invisible killer, causing 4.2 million human deaths in the world each year [1]
Non-metric multidimensional scaling (NMDS) analysis with the Bray–Curtis distance metric was used to analyze the fingerprints obtained from the ARISA analyses (Figure 1), with a probability ellipse for each location
Concerning naphthalene degradation of the most promising isolates assessed via gas chromatography mass spectrometry (GC-MS), our results indicate different decreases of naphthalene concentrations in the air phase of samples containing Lophiostoma sp., C. nebularis, C. dealbata, F. sporotrichioides, and

Summary

Introduction

Outdoor air pollution is an invisible killer, causing 4.2 million human deaths in the world each year [1]. Because of the significant surface area they span on Earth, which is estimated as a global leaf area of 508,630,100 km , leaves can have a substantial impact as a method for filtering air [4]. Plant leaves are a passive surface area for air filtration, they are the habitat for thousands microbial cells, including fungi and bacteria [5]. The phyllosphere can be defined as the aerial parts of living plants, which includes leaves, stems, buds, flowers, and fruits that provide a habitat for microorganisms [4]. Studies on phyllosphere microbiology have been mainly focusing on leaves, which are the plant structures with the highest global area. The leaf phyllosphere provides nutrients and a shelter for a large range of highly diverse microorganisms. Differently from other environmental niches, the conditions in the leaf phyllosphere can be considered as extreme due to the exposure to UV radiation and extreme temperatures [6,7]

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