Abstract:
A variety of anthropogenic sources release hazardous polyaromatic hydrocarbons
(PAHs) into the phyllosphere which is an excellent niche for diverse fungi, and some
of them have PAHs degradation capabilities. Therefore, this research attempted to
determine the PAHs (phenanthrene, anthracene, naphthalene, and pyrene) degradation
capability of phyllosphere inhabited Penicillium species. The leaf samples were
collected from highly polluted urban areas (Panchikawatta, Pettah, Orugodawatta,
Maradana, Sapugaskanda, and Colombo Fort) in Sri Lanka to isolate fungal species
inhabiting the phyllosphere. Furthermore, their distribution patterns among the leaf
tissue layers were studied using bright-field microscopic observations. Moreover, the
best PAHdegraders were screened out using plate assays and confirmed throughHigh
Performance Liquid Chromatography (HPLC) analysis. Further, their enzymatic activities
during the PAHs degradation were analyzed. As per the microscopic observations,
the highest fungal distribution was in the upper epidermis of the leaves followed by
the fungal distribution in the interspaces of palisade mesophyll layers. Out of isolated
fungal species, two Penicillium spp. (Penicillium citrinum P23B-91 and Penicillium
griseofulvum P9B - 30) showed the highest PAHs (phenanthrene, anthracene, naphthalene,
and pyrene) degradation capabilities. Manganese peroxidase (MnP) enzyme
dominated phenanthrene degradation in P. griseofulvum P9B - 30, which showed the
highest phenanthrene degradation ability (61%). In addition, P. citrinum P23B-91 was
good at degrading anthracene (88%) and also displayed a higher MnP activity during
the anthracene degradation than laccase and lignin peroxidase activities. The discoveries
from the toxicity assay during the PAHs degradation processes revealed that the
produced byproducts had no toxic effects on the fungal growth cycle and the phyllosphere.
Therefore this phyllosphere Penicillium spp. are ideal for the bioremediation of
polluted air in urbanized areas.
