# Changes in Intestinal Microbial Community of the Black Tiger Shrimp Penaeus monodon in Response to Triclocarban Exposure

## TL;DR

This study shows that triclocarban exposure affects the gut microbes of black tiger shrimp, potentially harming their health.

## Contribution

The study is the first to assess the impact of triclocarban on the intestinal microbiota homeostasis of Penaeus monodon.

## Key findings

- TCC exposure increased intestinal microbiota diversity but not significantly.
- TCC caused significant increases in Bacteroidetes and decreases in Tenericutes.
- TCC exposure enhanced metabolic pathways related to glycan and steroid biosynthesis.

## Abstract

Triclocarban (TCC), an antimicrobial agent previously widely used in personal care and health products, poses potential environmental contamination risks. The intestinal microbiota is closely associated with host health and remains sensitive to pollutant exposure. This study investigated the toxic effects of TCC on the intestinal microbiota of an edible black tiger shrimp, Penaeus monodon, by exposing them to 1 and 10 μg/L TCC for 14 days. The results indicated that TCC exposure increased intestinal microbiota diversity, though the change was not statistically significant. In terms of community composition, TCC led to a significant increase in Bacteroidetes and a significant decrease in Tenericutes. The abundances of both potentially beneficial bacteria and opportunistic pathogens showed decreasing trends, although these changes were not statistically significant. Functional prediction analysis revealed significant enhancements in metabolic pathways related to the biosynthesis and degradation of glycans, steroids, isoflavones, and other substances. These alterations demonstrate that TCC exposure disrupts the homeostatic balance of the intestinal microbiota in P. monodon, suggesting that this pollutant may pose a potential threat to aquatic organism health through its impact on the intestinal microbiota.

Triclocarban (TCC), a synthetic antimicrobial compound prevalent in personal care products, has emerged as a typical contaminant in aquatic ecosystems. Intestinal microbiota maintains the host’s health homeostasis by regulating nutrient metabolism and immunity and is regarded as a sensitive biomarker for the risk assessment of pollutants. Currently, there is still a lack of toxicity assessment of TCC on the intestinal microbiota homeostasis of shrimp. Therefore, this study employed 16S rDNA sequencing to explore intestinal microbiota perturbations in Penaeus monodon following subchronic exposure (14 days) to graded TCC concentrations (1 and 10 μg/L). The results showed that TCC exposure altered intestinal microbiota diversity, marked by increases in the ACE, Chao1, and Shannon indices and a decrease in the Simpson index; however, none of these changes reached statistical significance (p > 0.05). Furthermore, the community composition was also altered, characterized by a significant increase in Bacteroidetes and a significant decrease in Tenericutes (p < 0.05), alongside non-significant increases in Proteobacteria and decreases in Firmicutes (p > 0.05). The abundances of some putative beneficial bacterial genera (Alloprevotella, Bacteroidales S24-7 group_norank, Cetobacterium, Enterococcus and Lactobacillus) and harmful bacteria (Photobacterium and Aeromonas) were decreased (p > 0.05); the abundance of Vibrio was decreased in the T1 group but increased in the T10 group (p > 0.05). Additionally, the predicted functions of the intestinal microbiota, such as glycan biosynthesis and degradation, steroid and isoflavone biosynthesis, and nucleotide metabolism, were enhanced. These results indicated that TCC exposure had a negative effect on the homeostasis of the intestinal microbiota of P. monodon.