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Potential Protective Role of Amphibian Skin Bacteria Against Water Mold Saprolegnia spp.

Summary

Frogs have helpful bacteria living on their skin that can fight dangerous water molds called Saprolegnia. Scientists discovered that different types of bacteria, especially Bacillus species, can prevent these molds from growing. The study found that frogs from polluted or salty water actually had bacteria that were better at fighting the mold, likely because harsh conditions helped tougher bacteria survive. These protective bacteria might explain why adult frogs can resist these infections better than tadpoles or eggs.

Background

Amphibian populations face severe declines from environmental pollution, habitat destruction, climate change, and disease. Saprolegnia species are water molds causing saprolegniosis, particularly affecting early developmental stages of amphibians. Amphibian skin bacteria may provide protective mechanisms against these pathogenic oomycetes.

Objective

This study aimed to identify bacterial strains from Pelophylax perezi skin microbiomes with antagonistic activity against Saprolegnia spp., assess whether antagonistic potential varies by sampling site, evaluate the influence of different culture conditions on bacterial inhibitory capabilities, and identify the causative agent of P. perezi saprolegniosis.

Results

Saprolegnia australis was identified as the causative pathogen, with Bacillus, Serratia, Pseudomonas, and Aeromonas genera showing the strongest antagonistic effects. All frog populations contained bacteria capable of inhibiting Saprolegnia spp., with 21-35% of bacterial isolates showing anti-Saprolegnia potential. Antagonistic activity decreased significantly in nutrient-rich PG medium compared to nutrient-limited R2A medium.

Conclusion

Amphibian skin bacteria provide protective functions against Saprolegnia spp., with metabolically versatile strains from stressed environments showing enhanced antagonistic potential. Culture conditions significantly influence bacterial inhibitory capacity, suggesting that nutrient-limited environments promote secondary metabolite production. These findings support the role of skin microbiomes in protecting amphibians and highlight applications for preventing population declines.
  • Published in:Journal of Fungi (Basel),
  • Study Type:Experimental/Screening Study,
  • Source: PMID: 41003195, DOI: 10.3390/jof11090649
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