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Intestinal Inflammation, Dysfunction of Intestinal Digestion, and Disorder in the Intestinal Microbiota and Their Metabolites Caused by Oral Microcystis Exposure in Common Carp (Cyprinus carpio)

Year: 2025

Type: article

Abstract: Cyanobacterial blooms are a common water pollution phenomenon worldwide now. Among them, Microcystis blooms occur most frequently internationally, and most of them can produce hepatotoxins—microcystins (MCs). When the bloom occurs in water bodies, common carp, as the top consumers in the aquatic food chain, inevitably ingest a large amount of cyanobacteria. The effects on the intestinal digestion, immunity, and microbiota of the carp remain to be revealed. In the present study, 21-day gavage exposure to Microcystis paste (equivalent to 378.25 μg/kg of MC-LR) was conducted on juvenile carp mainly to investigate the adverse effects of MCs on the fish intestinal digestion, immunity, and microbiota. The results showed that Microcystis exposure caused intestinal barrier damage, intestinal structure destruction, and increased permeability. Analysis of the activities of three main intestinal digestive enzymes showed that Microcystis exposure affected the intestinal digestion of fish. Targeted metabolome analysis and 16S rRNA sequencing showed that the abundance of opportunistic pathogens such as Proteobacteria and Aeromonas increased in the exposed fish, and the contents of intestinal metabolites lipopolysaccharide (LPS) and trimethylamine oxide (TMAO) increased. However, the abundance of Firmicutes and Bacillus that produce short-chain fatty acids (SCFAs) was significantly reduced. These results indicated that Microcystis exposure could imbalance the intestinal flora and increase the abundance of Gram-negative bacteria, thereby activating the inflammatory response in the common carp. In summary, oral Microcystis exposure by the common carp can negatively affect fish digestion, immunity, and flora homeostasis of the fish intestinal tract. This study also provides a theoretical basis for a comprehensive evaluation of the beneficial effects of SCFAs on regulating metabolic disorders, activating lipid catabolism, and nutrient utilization of fish in aquaculture.

Source: Biology

DOI: 10.3390/biology15010038

Authors: Mengya Lou, Changqin Jing, Xin Liu, Yiyi Feng, Xiaoyu Li

Institutions: Henan Normal University, Henan Medical University

Language: English

Topic: Aquaculture disease management and microbiota

Subfield: Immunology

Field: Immunology and Microbiology

Domain: Life Sciences

SDGs: Life below water, Clean water and sanitation

Open Access status: gold

Estimated APC paid: $3,258