Biodegradation and utilization of 4-n-nonylphenol by Aspergillus versicolor as a sole carbon and energy source

Highlights: • A. versicolor is able to degrade 4-n-NP as the sole source of carbon and energy. • 4-n-NP removal by A. versicolor was accompanied by the formation of metabolites. • Radioactive experiments show complete 4-n-NP mineralization by A. versicolor. • 4-n-NP initiates heat production in the A. versicolor spores. - Abstract: 4-n-Nonylphenol (4-n-NP) is an environmental pollutant with endocrine-disrupting activities that is formed during the degradation of nonylphenol polyethoxylates, which are widely used as surfactants. Utilization of 4-n-NP by the filamentous fungus Aspergillus versicolor as the sole carbon and energy source was investigated. By means of gas chromatography–mass spectrometry, we showed that in the absence of any carbon source other than 4-n-NP in the medium, A. versicolor completely removed the xenobiotic (100 mg L⁻¹) after 3 d of cultivation. Moreover, mass spectrometric analysis of intracellular extracts led to the identification of eight intermediates. The mineralization of the xenobiotic in cultures supplemented with 4-n-NP [ring-¹⁴C(U)] as a growth substrate was also assessed. After 3 d of incubation, approximately 50% of the initially applied radioactivity was recovered in the form of ¹⁴CO₂, proving that this xenobiotic was completely metabolized and utilized by A. versicolor as a carbon source. Based on microscopic analysis, A. versicolor is capable of germinating spores under such conditions. To confirm these observations, a microcalorimetric method was used. The results show that even the highest amount of 4-n-NP initiates heat production in the fungal samples, proving that metabolic processes were affected by the use of 4-n-NP as an energetic substrate