Graphene oxide (GO) is a new type of nanomaterial with unique physicochemical properties and diverse applications,while it poses potential risk to human and environment.By screening from natural soil exposed to GO in the laboratory,we successfully obtained a novel bacterium,Labrys sp.WJW,which was able to use GO as sole carbon source for growth.Within 8 days,cell numbers of strain WJW increased to 16.76±3.21 folds using 100 mg/L GO.The bacterial biodegradation which resulted in formation of holes in the basal plane and functional group changes of GO was proved by Raman spectroscopy,atomic force microscopy,transmission electron microscopy,X-ray photoelectron spectroscopy,and thermogravimetric analyses.Aromatic intermediates with structure of benzoic and phenol were identified using gas chromatograph-mass spectrometry and liquid chromatography/time-of-flight/mass spectrometry.Combination of genomic and proteomic analyses were performed to explore and identify key enzymes for GO degradation.644 proteins were significantly shifted.By using bioinformatics approaches,the results revealed that part of the upregulated proteins were related to oxidation,ring cleavage and intermediates transmembrane processes,and GO was supposed to be degraded to benzoate and then further degraded for downstream processes.This study enriches our understanding and provides new insights into the environmental fate of GO.