E-cigarette vapor alters gut microbiota composition in zebrafish

Electronic cigarettes (e-cigarettes) have gained widespread popularity as alternatives to traditional tobacco products; however, their health effects remain poorly characterized. This study investigates the biological impact of e-cigarette vapor exposure, with and without nicotine, on gut microbiota composition and behavior in adult zebrafish. 16S rRNA sequencing revealed distinct microbial shifts following exposure. The nicotine-free vapor group (E-vapor medium; EVM) showed enrichment of Shewanellaceae and Barnesiellaceae while the nicotine-containing group (E-vapor medium with nictotine; EVMN) exhibited reductions in beneficial taxa such as Fusobacteriaceae, alongside an increase in Vibrionaceae. MetaCyc analysis identified enrichment of microbial pathways involved in xenobiotic degradation and oxidative stress responses, indicating both direct chemical metabolism and secondary stress adaptation. Lastly, behavioral assays demonstrated altered locomotor activity and reduced shock response in both EVM and EVMN groups, suggesting potential neurobehavioral dysregulation. This study highlights the potential toxicity of e-cigarette vapor and emphasizes the need to reassess the regulations of surrounding e-cigarette use.