Larimicin78-102, a new antimicrobial peptide from large yellow croaker fish, killed multiple aquatic pathogens, destroyed bacterial biofilms, reduced inflammation, and raised survival of infected fish to 95%.
95% survivalSurvival rate of large yellow croaker fish infected with V. fluvialis after treatment with the novel antimicrobial peptide Larimicin78-102
What the researchers found
Larimicin78-102 demonstrated broad-spectrum antibacterial activity against common aquatic pathogens including Vibrio fluvialis, Pseudomonas fluorescens, and Pseudomonas putida, plus anti-biofilm activity against all three. The peptide killed bacteria by disrupting both outer and inner cell membranes, causing ATP leakage and intracellular reactive oxygen species (ROS) accumulation.
In vivo, Larimicin78-102 raised survival of V. fluvialis-infected large yellow croaker to 95%. The peptide also modulated the immune response: it reduced pro-inflammatory cytokines TNF-α and IL-1β while upregulating the anti-inflammatory factor IL-4. It boosted innate immune gene expression (piscidin, hepcidin, lysozyme) and enhanced lysozyme enzymatic activity. The peptide showed good thermal stability, cation tolerance, and no cytotoxicity or hemolytic activity.
Why it matters
Large yellow croaker is one of the most farmed fish species in China, and bacterial diseases like Vibrio infections cause massive economic losses. With antibiotic resistance growing and regulatory pressure to reduce antibiotic use in aquaculture, finding effective antimicrobial peptides from the fish's own immune system is a particularly elegant solution. The 95% survival rate, combined with dual antimicrobial and immunomodulatory properties, makes this peptide one of the most promising aquaculture AMP candidates reported.
How the study worked
The Larimicin gene was identified through genomic analysis of large yellow croaker (L. crocea). Tissue distribution and infection-induced expression were characterized. A truncated peptide (Larimicin78-102) was synthesized and tested for: antimicrobial activity (MIC assays), LPS binding affinity, biofilm disruption, membrane permeabilization, ATP leakage, ROS generation, thermal stability, cation tolerance, cytotoxicity, and hemolytic activity. In vivo efficacy was tested in L. crocea challenged with V. fluvialis. Immune gene expression and cytokine modulation were measured by RT-qPCR.
What this study cannot tell us
The study is limited to aquaculture applications with a single fish species. Scalability and cost of peptide synthesis for commercial aquaculture use were not addressed. While no cytotoxicity was observed in vitro, long-term effects of repeated peptide administration on fish health are unknown. The 95% survival figure needs to be replicated across different infection doses and environmental conditions. Whether resistance to this peptide could develop with prolonged use was not tested.
How to read the evidence
This is a thorough preclinical study combining gene identification, in vitro antimicrobial and mechanistic testing, and in vivo survival experiments. The multi-level characterization provides strong evidence for the peptide's potential, though commercial applicability requires further development.
When this study was published
Published in 2025, this is a recent discovery contributing to the rapidly expanding library of fish-derived antimicrobial peptides for aquaculture applications.
The bigger picture
This study exemplifies the approach of mining host immune systems for antimicrobial peptides, then engineering truncated versions for practical use. Fish are particularly rich sources of AMPs because they rely heavily on innate immunity in their aquatic environment. Larimicin78-102 joins a growing arsenal of fish-derived antimicrobial peptides that could replace antibiotics in aquaculture — addressing both food safety and antimicrobial resistance concerns. The dual antimicrobial-immunomodulatory activity is especially valuable, as it mimics the multi-pronged defense strategy of the natural immune system.
Questions still open
- Can Larimicin78-102 be produced cost-effectively at scales needed for commercial aquaculture?
- Does the peptide maintain its 95% protective efficacy under real-world farming conditions with environmental stressors?
- Could this fish-derived antimicrobial peptide be adapted for human medicine against drug-resistant Vibrio or Pseudomonas infections?
Common questions
Where does this antimicrobial peptide come from?
How does this peptide kill bacteria?
Read the original research
A novel antimicrobial peptide Larimicin78-102 from large yellow croaker (Larimichthys crocea) shows potent antibacterial activity in vitro and enhances resistance to vibrio fluvialis infection in vivo.
Fish & shellfish immunology, 161, 110279
Citation
Zhou, Zhenzhen; Chen, Fangyi; Hao, Hua; Wang, Ke-Jian. (2025). A novel antimicrobial peptide Larimicin78-102 from large yellow croaker (Larimichthys crocea) shows potent antibacterial activity in vitro and enhances resistance to vibrio fluvialis infection in vivo.. Fish & shellfish immunology, 161, 110279. https://doi.org/10.1016/j.fsi.2025.110279