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

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 <i>Penaeus monodon</i> 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 (<i>p</i> > 0.05). Furthermore, the community composition was also altered, characterized by a significant increase in Bacteroidetes and a significant decrease in Tenericutes (<i>p</i> < 0.05), alongside non-significant increases in Proteobacteria and decreases in Firmicutes (<i>p</i> > 0.05). The abundances of some putative beneficial bacterial genera (<i>Alloprevotella</i>, <i>Bacteroidales S24-7 group_norank</i>, <i>Cetobacterium</i>, <i>Enterococcus</i> and <i>Lactobacillus</i>) and harmful bacteria (<i>Photobacterium</i> and <i>Aeromonas</i>) were decreased (<i>p</i> > 0.05); the abundance of <i>Vibrio</i> was decreased in the T1 group but increased in the T10 group (<i>p</i> > 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 <i>P. monodon</i>.