The biodegradation of nonylphenol (NP) by a newly isolated form of the larva fungal strain Metarhizium robertsii IM 6519 was investigated in this study. This isolate was capable of degrading 4-n-NP, and multiple metabolites were detected. The coexistence of parallel degradation pathways with versatile hydroxylation in different positions of the alkyl chain is a unique feature of this strain. Moreover, several metabolites previously described only in higher eukaryotes were detected in the fungal cultures. The degradation process led to the mineralization of 4-n-NP (with an efficiency of 36%), a great advantage of this strain that results in complete removal of toxic substrate from the environment. (C) 2015 Elsevier Ltd. All rights reserved.