Quinolone antibiotics stimulate bacterial mercury methylation by Geobacter metallireducens GS-15

• Published in: Bioresource technology 2024-12, Vol.413, p.131465, Article 131465
• Main Authors: Fang, Fang, Ding, Lingyun, Zhang, Yaoyu, Huang, Zhishan, He, Ningning, Zhang, Lele, Hung Wong, Ming, Pi, Bin, Xu, Nan, Tao, Huchun, Zhang, Lijuan
• Format: Article
• Language: English
• Subjects: Antibiotic resistance gene; Hormesis; Mercury methylator; Metal tolerance; Methylmercury
• ISSN: 0960-8524; 1873-2976; 1873-2976
• DOI: 10.1016/j.biortech.2024.131465

[Display omitted] •Bacterial Hg(II) methylation was stimulated under antibiotic stress of quinolones.•Quinolones inhibited cell growth at environmentally contaminated concentrations.•Short-term lomefloxacin exposure altered bioactivities of single bacterial cells.•Long-term ciprofloxacin stress enhanced antibiotic resistance and metal tolerance. Bacterial mercury (Hg) methylation is critical for bioremediating Hg pollution, but the impact of emerging antibiotics on this process has rarely been reported. This study innovatively investigated the interactions between Hg-methylating bacteria of Geobacter metallireducens GS-15 and two quinolone antibiotics: lomefloxacin (LOM) and ciprofloxacin (CIP) at 5 μg/L. Short-term LOM exposure increased methylmercury (MeHg) yield by 36 % compared to antibiotic-free conditions, caused by hormesis to alter bioactivities of single GS-15 cells. Long-term CIP exposure led to more antibiotic resistance and mercury tolerance in GS-15 cells, doubling MeHg productivity and significantly increasing expression of Hg methylation (hgcA by 95 folds) and antibiotic resistance (gyrA by 54 folds) genes, while mercury resistance gene merA only increased by 2.5 folds than without selective pressure. These results suggest quinolone antibiotics at environmentally contaminated concentrations stimulate bacterial Hg methylation to form highly toxic MeHg, raising considerable concern for the Hg-antibiotic complex in contaminated environments.