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Pyrene degradation by yeasts and filamentous fungi
M Cristina Romero1, Mónica L Salvioli, M Cecilia Cazau
1Instituto Spegazzini Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Argentina. anmabarr@museo.fcnym.unlp.edu.ar
Abstract:
The saprotrophic soil fungi Fusarium solani (Mart.) Sacc., Cylindrocarpon didymum (Hartig) Wollenw, Penicillium variabile Sopp. and the yeasts Rhodotorula glutinis (Fresenius) Harrison and Rhodotorula minuta (Saito) Harrison were cultured in mineral medium with pyrene. The remaining pyrene concentrations were periodically determined during 20 incubation days, using HPLC. To assess the metabolism of pyrene degradation we added 0.1 microCi of [4,5,9,10] 14C-pyrene to each fungi culture and measured the radioactivity in the volatile organic substances, extractable, aqueous phase, biomass and 14CO2 fractions. The assays demonstrated that F. solani and R. glutinis metabolized pyrene as a sole source of carbon. Differences in their activities at the beginning of the cultures disappeared by the end of the experiment, when 32 and 37% of the original pyrene concentration was detected, for the soil fungi and yeasts, respectively. Among the filamentous fungi, F. solani was highly active and oxidized pyrene; moreover, small but significant degradation rates were observed in C. didymum and P. variahile cultures. An increase in the 14CO2 evolution was observed at the 17th day with cosubstrate. R. glutinis and R. minuta cultures showed similar ability to biotransform pyrene, and that 35% of the initial concentration was consumed at the end of the assay. The same results were obtained in the experiments with or without glucose as cosubstrate.
Insights
Fusarium solani and Rhodotorula glutinis effectively metabolized pyrene as a sole carbon source. Other fungi showed varying degradation rates, with some activity observed even without cosubstrates.
Area of Science:
- Environmental microbiology
- Bioremediation of polycyclic aromatic hydrocarbons (PAHs)
Background:
- Polycyclic aromatic hydrocarbons (PAHs) like pyrene are environmental pollutants.
- Saprotrophic soil fungi and yeasts possess metabolic capabilities for degrading organic compounds.
Purpose of the Study:
- To investigate the pyrene degradation potential of selected soil fungi and yeasts.
- To assess the metabolic pathways and efficiency of pyrene biotransformation by these microorganisms.
Main Methods:
- Culturing of Fusarium solani, Cylindrocarpon didymum, Penicillium variabile, Rhodotorula glutinis, and Rhodotorula minuta in mineral media with pyrene.
- Quantification of pyrene concentration using High-Performance Liquid Chromatography (HPLC).
- Radioisotope tracing with [14C]pyrene to track metabolic fate in various fractions (CO2, biomass, etc.).
Main Results:
- Fusarium solani and Rhodotorula glutinis utilized pyrene as a sole carbon source, with degradation efficiencies of 32% and 37% respectively by day 20.
- Significant pyrene oxidation by F. solani was observed; C. didymum and P. variabile showed minor degradation.
- Rhodotorula glutinis and R. minuta demonstrated similar biotransformation abilities, consuming 35% of initial pyrene, irrespective of glucose cosubstrate.
Conclusions:
- Selected saprotrophic fungi and yeasts possess the capability to degrade pyrene.
- Fusarium solani and Rhodotorula glutinis are particularly effective in pyrene metabolism.
- The study highlights the potential of these microorganisms in bioremediation strategies for PAH-contaminated environments.