The Study Of Nonylphenol Biodegradation By Estuary Sediment Derived Fungi From LICUN River

As one of the persistent organic pollutants with estrogenic effects, nonylphenols（NPs） are the main raw materials for the synthesis of non-ionic surfactant nonylphenolpolyoxyethylene ethers （NPEs）, and also are the major stable degradation products ofNPEs in the environment. NP can affect the endocrine system of humans and animalscaused by tumors, carcinogen induced distortion. Because of their bioaccumulationand refractory characteristics, NPs are widely distributed in a variety of environmentalmatrixes, and are hard to remove.Methods for effective removal of NPs from the environment are still staying on astage of laboratory research. There are some flaws for traditional physical andchemical methods, such as high cost and incomplete removal of NPs. Greenbiodegradation methods without extra chemicals adding are attracting much attentionof many researchers. How to screen the efficient strains for degradation of NPs is stilla great challenge and is becoming a research hotspot. The domestic NPsbiodegradation researches are mostly focus on bacteria, but there are a few reportsabout fungal degradation of NPs.This study aimed to isolate the fungi from the sediment of LICUN estuary, andinvestigate their abilities in NP degradation. All the strains are identified by18SrDNA together with growing appearance. The contents of NPs before and after fungidegradation are detected by GC analysis. Feeding NP to culture fermentation anddetecting the change of NP by MS spectra are in order to find the influencing factorsof fungal degradation. The main conclusions are as follows:Four strains were isolated from LICUN river estuary sediment using radientdilution coating method within adding NP to solution, which were named asW-1,W-2,Y-1,Y-2. The strains were identified by extraction kit, PCR amplificationand18S rDNA sequencing. W-1was identified as Trichoderma asperellum, W-2wasNeosartorya sp., and both Y-1and Y-2were belonging to Penicillium sp. Four strains were incubated at different temperatures, and the best tempreaturewas29℃by comparing their growth state. NP could promote the growth of fungi, andthat NP did significant influence to W-1and W-2. The strain’s optimal growthcondition was suggested as: potato extract medium,29℃, natural pH, fungi dosage38.5mm², shaking speed140r min^-1.Under the optimal growth condition, the degradation rate and the degradationability of the four strains were investigated in the midium with nonylphenol initialconcentration of5μg mL^-1. The strains showed different removal rate and ability to NP.W-1,W-2showed faster removal rate over80%within3to5days, and the ultimatedegradation rate of up to95%. Y-1degradating NP was slower and the removal ratecan be to80%after10days, and final to87%; Y-2showed the slowest degradationrate of25%in the initial10days, and73%in14days, the final rate similar to that ofY-1（86%）.In Y-2study, the degradation results corresponded with the first-order kineticmodel. Degradation rate constant was0.0752d-1, and the half-life t1/2was9.2days.Fungi dosage and initial concentration of NP can affect little to the degradation of NP,but culture conditions, dynamic culture of degradation efficiency was about2.1timesfaster than the static culture. But the affect of medium was still unclear.Mass spectrometry was used to detecting the degradation metabolites of NP bythe four strains. The complex results suggested that different strains should havedifferent biotransformation pathways in NP degradating. Anisole, benzyl alcohol,2-methyl-1-phenyl butanol and hydroquinone were detected in W-1metabolites, and aprobable biotransformation pathway was proposed. Hydroxycinnamic acid wasdetacted in the metabolites of Y-1, but the other two strains metabolites were stillunclear. In current study, it was hard to say those substances were media or finalproducts in NP degradation pathway which needed a follow-up study.