Pyrite-driven denitrification by Paracoccus denitrificans: Promoted by enhanced electron transfer and extracellular
Wenhui Wang1, Jiaxiu Tan1, Yumei Hua1
1College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
Abstract:
Pyrite can be used in denitrification systems to improve efficiency. In this study, the role of pyrite and extracellular polymeric substances (EPS) was investigated in biological denitrification. In cultures of Paracoccus denitrificans, pyrite effectively enhanced denitrification efficiency, primarily by increasing key components of electron transport system such as cytochrome c and NADH, and upregulating the expression levels of genes involved in the synthesis of riboflavin and cytochrome c, along with denitrification-critical genes such as nosZ and napG. The denitrification of Paracoccus denitrificans in the presence of EPS exhibited a more complete reduction of nitrate than that in the absence of EPS. Electrochemical analysis revealed that the flavins and cytochrome c within EPS may contribute to electron transfer during denitrification. Riboflavin was reproduced by the cells, despite being removed along with EPS at the initial stage. Both pyrite and extracellular EPS could enhance nitrogen removal by facilitating electron transport processes.
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