Nonylphenol biodegradation pathway by Trichoderma asperellum from the estuary sediment

Several fungi were isolated from the LICUN river estuary sediment,where was contaminated seriously by nonylphenols (NPs).One target strain that can degrade NP was purified and selected by environmental selection pressure in high NP concentration media.It was identified as Trichoderma asperellum according to its sequence analysis of 18S rDNA.The NP biodegradation was studied in laboratory.The biodegradation metabolites were determined by LC/MS and used for establishing probable NP degradation pathway.The growth curve of the strain indicated that NP can promote its growth.It showed that NP at the concentration of 5 mg/L was eliminated from the culture medium by 71.4% during 3 d of incubation,whereas during 7 d of incubation by 87.2% and 14 d of incubation by 92.2%.Four compounds (2-methyl-1-phenyl butanol,3,5-dihydroxy benzoic acid,hydroquinone and anisole (or benzyl alcohol)) were identified as degradation metabolites by LC/MS.Two probable NP biodegradation pathways were proposed.NP was eventually converted to hydroquinone in PathⅠ,and to anisole (or benzyl alcohol) in path Ⅱ.