Diversity of cultivable bacteria involved in the formation of macroscopic microbial colonies (Cave silver) on the walls of a cave in Slovenia
compounds to oxidizing reduced inorganic compounds within the cave rocks. More importantly, the microbial diversity encountered was surprisingly high compared to what was expected given the amount and complexity of nutrients available in subterranean environments. This apparent violation of competitive exclusion or the ‘one species-one niche’ requirement (Hardin, 1960) led scientists to believe that within caves the selfish competition for resources is replaced by more cooperative and mutualistic microbial associations (Barton & Jurado, 2007). One eye-catching example of cave microbes are those found in Karstic and in lava caves which morphologically resemble white, yellow, grey, or pink bacterial colonies. Where present, these colonies can be observed throughout the cave as distinct one-millimetre INTRODUCTION