Impact of microplastic ingestion on the gut microbiome and lipid metabolism in a freshwater fish species.

Project Abstract

This study investigates the effects of microplastic ingestion on the gut microbiome composition and lipid metabolic pathways in a freshwater fish species, aiming to elucidate potential mechanisms linking environmental pollution to host physiology and health. We exposed adult specimens to environmentally relevant concentrations of degraded polyethylene microplastics (1–5 ?m) over a 12-week period, with a control group maintained in microplastic-free water. Gut content and mucosal samples were collected at 0, 6, and 12 weeks to assess microbial diversity, community structure, and functional potential using 16S rRNA gene sequencing and metagenomic shotgun sequencing. Concurrently, hepatic and intestinal lipid metabolism was evaluated through targeted lipidomics (LC-MS/MS) to quantify triglycerides, phospholipids, cholesterol esters, and free fatty acids, complemented by transcriptomic analysis (RNA-seq) of key enzymes and regulators involved in beta-oxidation, lipogenesis, and lipid transport, such as CPT1, ACC, FAS, PPARs, and LPL. Physiological and histopathological assessments, including growth metrics, condition factor, gut morphology, and inflammatory markers (IL-1?, TNF-?), were performed to correlate molecular changes with organismal health. Preliminary results indicate that microplastic exposure significantly alters gut microbial alpha diversity and beta-diversity, with enrichment of opportunistic taxa and depletion of fiber-degrading communities. Metagenomic data reveal enrichment of genes associated with xenobiotic metabolism and oxidative stress response, suggesting microbial adaptation to microplastic-associated toxins and adjuvant additives. Lipidomics show a shift toward altered hepatic and enterocyte lipid profiles, characterized by increased saturated and monounsaturated fatty acids and elevated cholesterol esters, coupled with decreased polyunsaturated fatty acids, indicative of disrupted lipid homeostasis. Transcriptomic analysis corroborates these findings, showing upregulation of lipogenic genes (FAS, ACC) and downregulation of fatty acid oxidation pathways (CPT1), along with upregulated inflammatory signaling. Histopathology reveals mild enteritis and steatosis-like changes in hepatocytes of exposed fish, along with increased mucosal immune cell infiltration. Statistical modeling demonstrates strong associations between specific microbial taxa shifts and lipidomic alterations, suggesting that dysbiosis may mediate metabolic disturbances. Pathway enrichment analyses highlight perturbations in bile acid signaling, short-chain fatty acid production, and xenobiotic metabolism, which together may influence host lipid handling and energy balance. The study provides mechanistic insights into how microplastics can disrupt gut ecosystem function and host lipid metabolism, potentially compromising growth, reproduction, and disease resistance in freshwater fish. These findings contribute to environmental risk assessment by linking microplastic exposure to molecular, cellular, and whole-organism outcomes, and they underscore the importance of mitigating microplastic pollution to protect aquatic health and ecosystem services.

Project Overview

What This Project Is About

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A straightforward, plain-language look at how microplastic particles eaten by a freshwater fish might influence its gut bacteria and how fats are processed in its body. The project checks whether microplastics can alter the mix of gut microbes and change lipid (fat) metabolism, which could affect the fish’s health and the broader aquatic ecosystem.

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The Problem It Addresses

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Microplastics are tiny plastic pieces found in water habitats. When fish ingest them, these particles may disrupt gut communities and metabolism, but the exact effects are not well understood. This study fills a gap by linking gut microbiome changes to fat metabolism in a live fish model, helping scientists assess ecological risks and inform policy.

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Objectives of the Project

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1. Describe how microplastics affect gut bacteria in the fish.
2. Assess changes in lipid metabolism indicators in response to microplastics.
3. Identify potential signs of stress or health impacts linked to gut and fat changes.
4. Explore dose-response relationships between microplastic exposure and observed effects.
5. Suggest implications for fish health and aquatic food webs.

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What You Will Do Step by Step

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1. Review background literature on microplastics and fish gut health.
2. Design a simple exposure setup with varying microplastic levels.
3. Collect gut samples and measure microbiome composition (basic sequencing data).
4. Analyze lipid metabolism markers (e.g., fat storage indicators) from tissues.
5. Compare treated groups to controls to detect differences.
6. Interpret results in the context of fish health and ecosystem risk.

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Expected Outcome

We expect to find measurable changes in gut microbial communities and lipid metabolism in fish exposed to microplastics, with higher exposure showing stronger effects. The findings could indicate potential health risks for fish and inform environmental management decisions.