Meta-metabolomic Responses of River Biofilms to Cobalt Exposure and Use of Dose-response Model Trends as an Indicator of Effects

Abstract

ABSTRACTMetabolites are low molecular-weight molecules produced during cellular metabolism. The global expression of the meta-metabolome (metabolomics at the community level) could thus potentially be used to characterize the exposure of an organism or a community to a specific stressor. Here, the meta-metabolomic fingerprints of mature biofilms were examined after 1, 3 and 7 days of exposure to five concentrations of cobalt (0, 1 x 10-7, 1 x 10-6, 5 x 10-6and 1 x 10-5M) in aquatic microcosms. The global changes in meta-metabolomic fingerprints were in good agreement with those of the other biological parameters studied (cobalt bioaccumulation, biomass, chlorophyll content). To better understand the dose-responses of the biofilm meta-metabolome, the untargeted LC-HRMS metabolomic data were further processed using the DRomics tool to build dose-response model curves and to calculate benchmark doses (BMD). These BMDs were aggregated into an empirical cumulative density function. A trend analysis of the metabolite dose-response curves suggests the presence of a concentration range inducing defense mechanisms (CRIDeM) between 4.7 x 10-7and 2.7 x 10-6M, and of a concentration range inducing damage mechanisms (CRIDaM) from 2.7 x 10-6M to the highest Co concentration. The present study demonstrates that the molecular defense and damage mechanisms can be related to contaminant concentrations and represent a promising approach for environmental risk assessment of metals.SYNOPSISThis study focuses on the interpretation of the metabolite dose-response trends in river biofilms exposed to cobalt to identify concentration range inducing cellular mechanisms and improve the environmental risk assessment of metals.