Effects of typical engineered nanomaterials on 4-nonylphenol degradation in river sediment: basing on bacterial community and function analysis
In this study, we presented a detailed investigation on the effects of typical engineered nanomaterials (ENMs) (including Fe2O3 nanoparticles, Fe3O4 nanoparticles and multi-wall carbon nanotubes (MWCNTs) on 4-nonylphenol (4NP) degradation, diversity and function of bacterial communities in sediments. Results demonstrated that iron oxides promoted 4NP degradation and enzyme activities in sediments, while MWCNTs inhibited those activities. LEfSe analysis suggested that iron oxides incorporation discriminative enriched iron-reducing bacteria, including Pantoea, Shewanella and Shewanellaceae contributing to iron reduction and organic degradation. PICRUSt analysis demonstrated that 4NP contamination promoted the expression of biodegradation related genes, including amino acid metabolism, carbohydrate metabolism, energy metabolism and xenobiotic biodegradation and metabolism. Interestingly, compared to MWCNTs, iron oxides incorporation brought about enhanced expressions of iron regulated proteins, including ferric uptake regulator (Fur), diphtheria toxin regulator (DtxR), ferrous iron transport (FeoB) and iron complex transport systems. These results indicate that iron oxides endow a better advantage in 4NP degradation, in contrast, pragmatic prospection of MWCNTs is necessary since the fact of extending persistence of 4NP in sediments. The study may be favored to evaluate the secure applications of ENMs in the aquatic environment basing on full understanding of their environmental fate.