Frog populations are declining due to various diseases and environmental challenges. This research discovered that bacteria living on frog skin can protect against harmful water molds called Saprolegnia that attack amphibian eggs. Scientists found that different types of bacteria, particularly Bacillus species, can inhibit the growth of these water molds. The protective effect was strongest in nutrient-poor conditions similar to natural water environments, suggesting that the bacterial symbiosis with frogs may be an important defense mechanism.