Abstract
Tolerance to Polycyclic Hydrocarbons Aromatic (PAHs) is considered an important characteristic when assessing the bioremediation potential of microorganisms. Given this, the objective of this research was to assay filamentous fungi from the Amazon region, isolated from sediments with differents levels of contamination by PAHs, for tolerance to phenanthrene and pyrene. To achieve this, fungal cultures plugs (5 mm), obtained after 7 days growth, were transferred to petri dishes containing 20% Sabouraud dextrose agar medium, after surface innoculation with phenanthrene and pyrene crystals, separately. Radial mycelial growth was evaluated after 10 days at five different concentration levels for each contaminant and control group, all in triplicate for each treatment. Fungal growth and growth inhibition rates were calculated. The average growth of the colonies in each treatment was compared with one-way ANOVA, followed by a Tukey Test (p < 0,05). All fungi showed tolerant to phenanthrene and pyrene. However, Hypoxylon sp. showed the lowest growth inhibition rate and average growth rates significantly different of the other six tested species. Hypoxylon sp. has been shown to be a promising genetic resource for use in new studies of PAHs degradation.
Highlights
Polycyclic Aromatic Hydrocarbons (PAHs) are important environmental organic pollutants, consisting of two to eight benzene rings fused together in linear, angular or grouped forms
The study results indicated that the seven tested fungi had different responses to the presence of the assayed PAHs
The high inhibition of fungal growth by phenanthrene and the low growth inhibition by pyrene confirm the greater toxicity of phenanthrene, corroborating the results previously reported in the literature
Summary
Polycyclic Aromatic Hydrocarbons (PAHs) are important environmental organic pollutants, consisting of two to eight benzene rings fused together in linear, angular or grouped forms. The existing environmental legislation on PAHs has been determined by the US Environmental Protection Agency (United States Environmental Protection Agency [US-EPA], 1983), which ranked a group of 16 individual PAHs as priority pollutants Among these compounds, phenanthrene, consisting of three aromatic rings is known as a major constituent of oil and its derivatives. Pyrene, composed of four aromatic rings, originates primarily from the thermal decomposition of organic matter and its subsequent recombination (Cerniglia 1993; Samanta, Sing, & Jain, 2002; Haritash & Kaushik 2009) Both of these PAHs are known for their toxicity and have been recommended as models for biodegradation studies because they possess physical characteristics similar to those other highly carcinogenic PAHs (US-EPA, 1983; Samanta et al, 2002)
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