Abstract
Soil contamination with petroleum asphaltenes represents a critical environmental hazard due to their recalcitrant nature and their potential long-term adverse effects on ecosystems, plants, animals, and human health. Bioremediation using microbial consortia capable of degrading heavy hydrocarbons offers a promising strategy for the efficient removal of asphaltenes from contaminated soils. This study aimed to develop a novel fungal consortium highly tolerant to asphaltenes for the bioremediation of contaminated soils and evaluate transcriptional responses during asphaltene degradation. The consortium, composed of Aspergillus oryzae, Penicillium citrinum, and Aspergillus sydowii, was evaluated in microcosm systems containing asphaltene-contaminated soil, and transcriptomic analyses were conducted to assess gene activity. Bioremediation assays revealed that the consortium not only removed but also mineralized asphaltenes, achieving a degradation of up to 55.6 wt% of 5000 mg of asphaltenes kg(-1) in 30 days. Additionally, it exhibited remarkable tolerance to asphaltenes at concentrations exceeding 100,000 mg of asphaltenes l(-1). Transcriptomic profiling indicated that cytochrome P450 monooxygenases and extradiol dioxygenases were primarily involved during the initial stages of degradation, followed by upregulation of genes encoding laccases and DyP-type peroxidases, suggesting a coordinated metabolic response to the breakdown of complex aromatic compounds. The consortium demonstrated the ability to adapt and overexpress hydrocarbon-degrading genes in response to asphaltene exposure, underscoring its potential as an effective and viable bioremediation tool.