Enhanced chloramphenicol biodegradation and sustainable electricity generation via co-cultured electroactive biofilms modified with in-situ self-assembled gold nanoparticles and reduced graphene oxide

Abstract

Bioelectrochemical technology emerges as a promising approach for addressing the challenge of antibiotic residue contamination. This research innovated by incorporating in-situ self-assembled gold nanoparticles (Au-NPs) and reduced graphene oxide (rGO) into a co-cultured electroactive biofilm (EAB) of Raoultella sp. DB-1 and Shewanella oneidensis MR-1 (Au-rGO@R/S-C). Supported by the rGO scaffold, the embedding of Au-NPs at key intercellular sites, and the adhesion of extracellular polymeric substance (EPS), the Au-rGO@R/S-C EAB enhanced the bioelectrochemical performance of the inoculated microbial fuel cell (MFC), with a 34.4% increase in the maximum voltage output and a 1.95-fold rise in the maximum power density, enabling the complete degradation of 100 mg/L chloramphenicol within 24 h. Notably, the Au-rGO@R/S-C EAB adapted to increased chloramphenicol stress by amplifying EPS secretion, especially with an elevated protein/polysaccharide ratio. Further analysis indicated a positive correlation between excessive production of EPS, particularly the increase in tightly bound EPS, and the stability in balancing the self-protection and extracellular electron transfer efficiency of the Au-rGO@R/S-C EAB under environmental stress. Our findings present a crucial strategy for the rational engineering of EABs, leveraging their dual potential in both environmental remediation and clean energy production.

Keywords: Chloramphenicol degradation; Co-culture; Electroactive biofilm (EAB); Extracellular electron transfer (EET); Self-assembly biohybrids.