Effects of geosmin and 2-methylisoborneol exposure on the gill transcriptome of Nile tilapia (Oreochromis niloticus)

Geosmin (GSM) and 2-methylisoborneol (2-MIB) are two common earthy-musty compounds produced by various microorganisms in aquatic environments that cause off-flavors in fish. However, few studies have explored the molecular responses of fish gills to GSM and 2-MIB exposure. In this study, Nile tilapia (Oreochromis niloticus) were exposed to 10 μg/L of both GSM and 2-MIB for 24 h, after which gill samples were collected for transcriptome sequencing. A total of 65 and 116 differentially expressed genes (DEGs) were identified in the GSM and 2-MIB treatment groups, respectively. Gene Ontology (GO) analysis highlighted biological processes related to metabolism, cellular processes, and catalytic activity. Fifteen DEGs, 12 upregulated and 3 downregulated, were shared between the GSM and 2-MIB treatments. KEGG pathway analysis revealed enrichment in pathways associated with immune response, cell signaling, and metabolism. These findings contribute to a deeper understanding of the molecular mechanisms underlying the effects of GSM and 2-MIB exposure on fish.