Characterization of the Mycoremediation of n-Alkanes and Branched-Chain Alkanes by Filamentous Fungi from Oil-Polluted Soil Samples in Kazakhstan

Abstract

For decades, researchers have focused on containing terrestrial oil pollution. The heterogeneity of soils, with immense microbial diversity, inspires them to transform pollutants and find cost-effective bioremediation methods. In this study, the mycoremediation potentials of five filamentous fungi isolated from polluted soils in Kazakhstan were investigated for their degradability of n-alkanes and branched-chain alkanes as sole carbon and energy sources. Dry weight estimation and gas chromatography–mass spectrometry (GC-MS) monitored the growth and the changes in the metabolic profile during degradation, respectively. Penicillium javanicum SBUG-M1741 and SBUG-M1742 oxidized medium-chain alkanes almost completely through mono- and di-terminal degradation. Pristane degradation by P. javanicum SBUG-M1741 was >95%, while its degradation with Purpureocillium lilacinum SBUG-M1751 was >90%. P. lilacinum SBUG-M1751 also exhibited the visible degradation potential of tetradecane and phytane, whereby in the transformation of phytane, both the mono- and di-terminal degradation pathways as well as α- and ß-oxidation steps could be described. Scedosporium boydii SBUG-M1749 used both mono- and di-terminal degradation pathways for n-alkanes, but with poor growth. Degradation of pristane by Fusarium oxysporum SBUG-M1747 followed the di-terminal oxidation mechanism, resulting in one dicarboxylic acid. These findings highlight the role of filamentous fungi in containing oil pollution and suggest possible degradation pathways.

Comparative Bioremediation of Tetradecane, Cyclohexanone and Cyclohexane by Filamentous Fungi from Polluted Habitats in Kazakhstan

“…These are probably also the reasons why there are far-reaching fields of research on this species, but very little on the biodegradation of alkanes. F. oxysporum strains were only described as tetradecane [ 14 ] or pristane (a branched chain alkane) [ 12 ] degraders. More frequently, F. oxysporum strains have been described as utilizers of aromatics or polycyclic aromatic hydrocarbons [ 38 , 39 , 40 , 41 , 42 ] or as strains isolated on these hydrocarbons or on crude oil [ 43 , 44 ].…”

“…A 7-day-old plate incubated with cell material was fixed as a starting plate for all further procedures. Microscopic features of each strain were examined using Leica DM 2500 LED microscope (Wetzlar, Germany) as described previously [ 12 ], while phenotyping via macroscopic examination of the cultures grown on MAg plates was used to determine their filamentous nature. A simplified overview of the culturing methodology is depicted in Figure 1 .…”

“…The cultivation of the eight fungal strains for biodegradation experiments and corresponding control cultures was performed in malt broth followed the method described by Gaid et al [ 12 ]. For incubation with tetradecane, eight sterile 500 mL wide-neck round-bottom flasks with cotton plugs were used.…”

“…The biomass was measured as dry weight as described previously [ 12 ]. Cell suspension was filtered under vacuum through an oven-dried and weight-determined filter.…”

“…While several contemporary studies have focused on the bioremediation capabilities of bacterial strains, the potential contributions of fungi are increasingly recognized [ 11 , 12 , 13 ]. Emerging terms like “mycoremediation” and “mycodegradation” highlight the specificity of fungal-based degradation techniques in treating organic pollutants.…”