Co-infecting pathogen lineages have additive effects on host bacterial communities

Area of Science:

• Microbiology
• Ecology
• Amphibian disease

Background:

• Amphibian skin bacteria can protect against chytridiomycosis, a disease caused by the fungus Batrachochytrium dendrobatidis (Bd).
• Different Bd lineages, including the panzootic Bd-GPL and enzootic Bd-Asia-2/Brazil, have varying impacts on amphibian populations.
• The interaction between Bd lineages and amphibian skin microbiomes is not well understood, especially in mixed infections.

Purpose of the Study:

• To investigate how different Bd lineages (Bd-Asia-2/Brazil and Bd-GPL) and their recombinants affect amphibian skin bacterial communities in single and mixed infections.
• To assess the impact of laboratory conditions on amphibian skin bacterial communities.
• To understand host-microbiome-pathogen dynamics in the context of emerging Bd threats.

Main Methods:

• Laboratory experiment involving single and mixed infections with different Bd lineages.
• 16S rRNA amplicon sequencing to analyze amphibian skin bacterial community composition and diversity.
• Comparison of bacterial communities under different Bd infection treatments and laboratory acclimatization.

Main Results:

• No significant differences in bacterial diversity were observed among different Bd treatments, despite varying infection intensities.
• Mixed Bd infections showed an additive effect on bacterial alpha diversity, suggesting complex interactions.
• Bd-GPL demonstrated a greater ability to alter skin bacterial community composition compared to other lineages.
• Laboratory conditions led to a substantial reduction in bacterial diversity and altered community structure.

Conclusions:

• Bd genotypes interact in complex ways with amphibian skin bacteria during coinfections.
• Bd-GPL may have a more pronounced impact on the amphibian skin microbiome.
• Experimental conditions, such as laboratory settings, can significantly influence microbial community structure and should be carefully considered in ecological studies.