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Abstract Tetrodotoxin (TTX) is a potent neurotoxin that accumulates in Takifugu rubripes, commonly known as pufferfish, through the ingestion of TTX-bearing organisms as part of their food chain. Although it is believed that pufferfish use TTX to relieve stress, there are currently no data available on the impact of TTX on the gut microbiota of pufferfish. To address this gap, our study aimed to investigate whether administering TTX to fish could alter their gut microbiota and overall health under various salinity conditions, specifically, 30.0 ppt, 8.5 ppt, and 1.7 ppt salinity, which represent full-strength, isosmotic, and low-salinity stress, respectively. We analyzed the effects of TTX ingestion on the community structure, core microbiome, and metabolic capabilities of the gut microbiome using high-throughput sequencing technologies. The predominant bacterial taxa within the gut microbiome were Firmicutes (21-85%), Campilobacterota (2.8-67%), Spirochaetota (0.5-14%), and Proteobacteria (0.7-9.8%), with Mycoplasma, uncultured Arcobacteraceae, Brevinema, Vibrio, Rubritalea, and uncultured Pirellulaceae as core genera. Our findings indicated that the impact of TTX on high-abundance genera at 30.0 ppt and 8.5 ppt salinity levels was negligible, indicating their stability and resilience to TTX ingestion. However, at 1.7 ppt, TTX-fed fish showed a significant increase in uncultured Arcobacteraceae, which was reportedly beneficial for the host, implying that the ingestion of TTX can shape the gut microbiota and contribute to T. rubripes juveniles’ ability to cope with salinity stress conditions. Furthermore, our analysis of TTX-fed fish revealed taxonomic alterations in low-abundance taxa, which altered the predicted functions of the gut microbiota at all salinity levels. These results suggest that TTX administration could cause subtle effects on the metabolic functions of gut microbial communities, which in turn could affect host physiology. Overall, our study provides insights into the complex relationship between a TTX-accumulating animal, T. rubripes, and its gut microbiota.
Wassel et al. (Tue,) studied this question.