Exposed to Sulfamethoxazole induced hepatic lipid metabolism disorder and intestinal microbiota changes on zebrafish (Danio rerio)

Performance of electro-assisted ecological floating bed in antibiotics and conventional pollutants degradation: Mechanisms and microbial response

Electro-assisted technology is promising for enhancing plant activity, optimizing functional microbial communities, and significantly strengthening pollutant removal efficiency. In this study, four reactors were designed as control group (CG), Hydrocotyle vulgaris L. ecological floating bed (PEFB), microbial fuel cell (MFC), and Hydrocotyle vulgaris L. ecological floating bed-microbial fuel cell (PEFB-MFC) to investigate the efficiency and mechanisms for the synchronous removal of conventional and antibiotic contaminants. Results showed that PEFB-MFC hold superior removal performance for sulfamethoxazole (61%), tetracycline (61%), CODCr (65%), NH4+-N (86%), TN (41%), and TP (51%). High-throughput sequencing indicated that Pseudomonadota and Actinomycetota were the predominant phyla in the different reactors. Metagenomic sequencing results showed that pollutant degradation-related metabolic functions, such as those involved in carbohydrate and amino acid metabolism in PEFB-MFC exhibited superior abundance compared to the other reactors. LC-MS analysis revealed sulfamethoxazole degradation occurred through active-site cleavage, and tetracycline underwent demethylation, aldehyde formation, dehydroxylation. This study offers a deeper insight into electro-enhanced PEFB on decontamination performance and functional microbial communities.

Polyvinyl chloride microplastics in the aquatic environment enrich potential pathogenic bacteria and spread antibiotic resistance genes in the fish gut

Microplastics and antibiotics coexist in aquatic environments, especially in freshwater aquaculture areas. However, as the second largest production of polyvinyl chloride (PVC) in the world, the effects of co-exposure to microplastics particles and antibiotics on changes in antibiotic resistance gene (ARG) profiles and the microbial community structure of aquatic organism gut microorganisms are poorly understood. Therefore, in this study, carp (Cyprinus carpio) were exposed to single or combined PVC microplastic contamination and oxytetracycline (OTC) or sulfamethazine (SMZ) for 8 weeks. PVC microplastics can enrich potential pathogenic bacteria, such as Enterobacter and Acinetobacter, among intestinal microorganisms. The presence of PVC microplastics enhanced the selective enrichment and dissemination risk of ARGs. PVC microplastics combined with OTC (OPVC) treatment significantly increased the abundance of tetracycline resistance genes (1.40-fold) compared with that in the OTC exposure treatment, revealing an obvious co-selection effect. However, compared with those in the control group, the total abundance of ARGs and MGEs in the OPVC treatment groups were significantly lower, which was correlated with the reduced abundances of the potential host Enterobacter. Overall, our results emphasized the diffusion and spread of ARGs are more influenced by PVC microplastics than by antibiotics, which may lead to antibiotic resistance in aquaculture.

Biological toxicity of sulfamethoxazole in aquatic ecosystem on adult zebrafish (Danio rerio)

This study evaluated the impacts of sulfamethoxazole (SMX) on antioxidant, immune, histopathological dynamic changes, and gut microbiota of zebrafish. SMX was carried out five groups: 0 (C), 3 mg/L (T3), 6 mg/L (T6), 12 mg/L (T12), and 24 mg/L (T24), with 5 replicates per group for an 8-weeks chronic toxicity test. It was found that SMX is considered to have low toxicity to adult zebrafish. SMX with the concentration not higher than 24 mg/L has no obvious inhibitory effect on the growth of fish. Under different concentrations of SMX stress, oxidative damage and immune system disorder were caused to the liver and gill, with the 12 and 24 mg/L concentration being the most significant. At the same time, it also causes varying degrees of pathological changes in both intestinal and liver tissues. As the concentration of SMX increases, the composition and abundance of the gut microbiota in zebrafish significantly decrease.

Transcriptomic Association Analysis of the Metabolic Mechanism of Sulfamethoxazole in Channel Catfish (Ictalurus punctatus)

Sulfamethoxazole is a widely used antimicrobial drug used to treat bacterial diseases in aquaculture. To understand the gene expression in channel catfish liver after treatment with sulfamethoxazole, in this study, the treatment group received sulfamethoxazole (100 mg/kg bw), which was administered orally once, and samples were taken at 5 h, 12 h, and 6 d after the administration of sulfamethoxazole, while the control group was orally administered sterile water. To further identify potentially significant genes, a transcriptome analysis using RNA-seq was carried out. More than 50 million high-quality reads were found. After filtering and quality analysis, these reads were identified as 54,169,682, 51,313,865, 51,608,845, and 49,333,491. After counting 23,707 of these transcripts for gene expression, it was discovered that 14,732 of them had genes with differential expression. Moreover, we found that the annotation with the most GO variation was "cellular process" (1616 genes), "metabolic process" (1268 genes), "binding" (1889 genes), and "catalytic activity" (1129 genes). KEGG pathways showed that the "metabolic pathway" was the pathway that was significantly enriched in both experimental groups when comparing the experimental groups: 5 h and 12 h (128 genes); 5 h and 6 d (332 genes); and 12 h and 6 d (348 genes). Also, UDP- glucuronosyltransferase (ugt), which is associated with glucuronidation, and UDP-glucuronosyltransferase 2C1-like (ugt2a1) showed significant upregulation. Carboxylesterase 5A-like (ces3), which promotes fatty acyl and cholesteryl ester metabolism, and the glutathione transferase family were upregulated in the expression of sulfamethoxazole metabolism in the liver, which significantly affected the metabolic effects of the drug. Meanwhile, dypd, uck2b, and rrm2, which are related to nucleotide synthesis and metabolism, were upregulated. Our study extends the knowledge of gene expression in drug metabolism in channel catfish and further provides insight into the molecular mechanism of sulfamethoxazole metabolism.

Exploring the impact of antibiotics, microplastics, nanoparticles, and pesticides on zebrafish gut microbiomes: Insights into composition, interactions, and health implications

This review addresses the impact of various chemical entities like pesticides, antibiotics, nanoparticles and microplastic on gut microbiota of zebrafish. Gut microbiota plays a vital role in metabolic regulation in every organism. As majority of metabolic pathways coordinated by microbiota, small alterations associated with mild to serious outcomes. Because of their unstoppable usage in day-to-day life, the present-day research on gut microbiota is mostly comprising aforementioned chemicals. It is better to understand how gut microbiome is dysbiosed by various environmental factors, to keep our microbiota safe. We tried to delineate the natural flora of zebrafish gut microbiome and the metabolic and other pathways associated and what are the common flora that was dysbiosed during the treatment. Based on the existing literature, we reviewed pesticides like Imazalil, Difenoconazole, Chlorpyrifos, Metamifop, Carbendazim, Imidacloprid, Phoxim, Niclosamide, Dieldrin, and antibiotics like Oxytetracycline, Enrofloxacin, Florfenicol, Sulfamethoxazole, Tetracycline, Streptomycin, Doxycycline, and in the category of nanoparticles, Titanium dioxide nanoparticles (nTiO2), Abalone viscera hydrolysates decorated silver nanoparticles (AVH-AgNPs), Lead-halide perovskite nanoparticles (LHP NPs), Copper nanoparticles (Cu-NPs), silver nanoparticles (Ag-NPs) and microplastic types like polyethylene and polystyrene microplastic. Other studies with miscellaneous chemical entities on zebrafish gut microbiome include Ferulic acid, Polychlorinated biphenyls, Cadmium, Disinfection by-products, Triclosan, microcystin-LR, Fluoride, and Amitriptyline.

Short-term exposure to enrofloxacin causes hepatic metabolism disorder associated with intestinal flora dysbiosis in adult marine medaka (Oryzias melastigma)

Enrofloxacin (ENR) is a widely used fluoroquinolone antibiotic that is frequently detected in the environment. Our study assessed the impact of short-term ENR exposure on the intestinal and liver health of marine medaka (Oryzias melastigma) using gut metagenomic shotgun sequencing and liver metabolomics. We found that ENR exposure resulted in imbalances of Vibrio and Flavobacteria and enrichments of multiple antibiotic resistance genes. Additionally, we found a potential link between the host's response to ENR exposure and the intestinal microbiota disorder. Liver metabolites, including phosphatidylcholine, lysophosphatidylcholine, taurocholic acid, and cholic acid, in addition to several metabolic pathways in the liver that are closely linked to the imbalance of intestinal flora were severely maladjusted. These findings suggest that ENR exposure has the potential to negatively affect the gut-liver axis as the primary toxicological mechanism. Our findings provide evidence regarding the negative physiological impacts of antibiotics on marine fish.

Bacillus licheniformis FA6 Affects Zebrafish Lipid Metabolism through Promoting Acetyl-CoA Synthesis and Inhibiting β-Oxidation

The intestinal microbiota contributes to energy metabolism, but the molecular mechanisms involved remain less clear. Bacteria of the genus Bacillus regulate lipid metabolism in the host and are thus commonly used as beneficial probiotic supplements. In the present study, Bacillus licheniformis FA6 was selected to assess its role in modulating lipid metabolism of zebrafish (Danio rerio). Combining 16S rRNA high-throughput sequencing, micro-CT scan, metabolic parameters measurement, and gene expression analysis, we demonstrated that B. licheniformis FA6 changed the gut microbiota composition of zebrafish and increased both the Firmicutes/Bacteroidetes ratio and lipid accumulation. In terms of metabolites, B. licheniformis FA6 appeared to promote acetate production, which increased acetyl-CoA levels and promoted lipid synthesis in the liver. In contrast, addition of B. licheniformis lowered carnitine levels, which in turn reduced fatty acid oxidation in the liver. At a molecular level, B. licheniformis FA6 upregulated key genes regulating de novo fatty acid synthesis and downregulated genes encoding key rate-limiting enzymes of fatty acid β-oxidation, thereby promoting lipid synthesis and reducing fatty acid oxidation. Generally, our results reveal that B. licheniformis FA6 promotes lipid accumulation in zebrafish through improving lipid synthesis and reducing β-oxidation.