Emerging infectious diseases of wildlife are increasingly recognised as a severe threat to biodiversity and human health. Fungal diseases have caused some of the most severe die-offs and extinctions ever reported in wild species. One specific fungus, the chytrid Batrachochytrium dendrobatidis (Bd), is playing a key role in amphibian declines worldwide. Bd has been detected in half of the amphibian species examined, causing the catastrophic declines and extinction of at least 200 species of frogs. However, not all amphibian species become infected with Bd, and even some of the infected ones never develop the disease. Understanding why some species are resistant will be a crucial step to develop methods to control Bd in declining amphibian populations. The presence on the amphibian skin of specific types of symbiotic bacteria that discourage the growth of Bd might explain the resistance reported for some species. However, almost nothing is known about how different is the skin microbiome between amphibian species and populations, and how environmental conditions shape its composition and diversity. Furthermore, the probiotic effect of most of these skin bacteria has never been tested despite their potential role against fungal diseases. In this project, we will investigate the variability of the amphibian skin microbiomes across species and environments. An ultimate objective is to identify bacterial sets with probiotic activity against pathogenic fungi.