Deciphering microplastic-driven denitrification in rivers: carbon bioavailability, keystone microbes and electron
Cheng Yang1, Xingnian Ren1, Jianhao Song1
1School of Environmental Science and Engineering, Southwest Jiaotong University, Chengdu, 611700, China.
Abstract:
Continuous input of microplastics (MPs) into rivers poses an increasingly serious ecological threat. MPs gradually release dissolved organic carbon during aging and degradation. However, the molecular mechanisms by which MP-released carbon drive denitrification in sediments remain unclear. This study combined the data of 251 freshwater plastisphere and microcosm experiment to resolve this issue. We found high denitrifier abundance (66.65% at phylum level) in plastispheres, and microcosm experiments confirmed the utilization of MPs as a carbon source. Relative to glucose, pristine MPs exhibited 78.56%-90.58% of the denitrification-supporting performance, while aged MPs reached 83.17%-95.39%. This enhancement in bioavailability correlated with a 43.04-632.29% greater weight loss in aged MPs compared to pristine MPs. Compared with the control, pristine MPs increased the electron transfer efficiency by 32.29%-533.65%, and aged MPs further enhanced it by 10.26%-127.24% relative to pristine MPs. MP-carbon increased the relative contribution of bacterial denitrification from 45.80 % to 51.20 % compared to glucose. Especially, keystone bacteria (Thermosporothrix, Gemmatirosa, Daejeonella, and Geobacter) harbored genes associated with both denitrification and MPs degradation. Genome-scale metabolic models further predicted that metabolites generated from MPs degradation, including butyryl-CoA, stearoyl-CoA, benzaldehyde, and succinate, might participate in denitrification-related electron supply and denitrification reduction processes through distinct metabolic pathways. These results provide new insights into the impact of MPs on denitrification.
Related Concept Videos
Freshwater Microbial Ecology
Microbial Wastewater Treatment
Marine Microbial Ecology
Metabolism of Chemolithotrophs
Microbes and Other Elemental Cycles
Microbial Nutrition


