Ecology of Rare Microorganisms

Abstract

Abstract Microbial communities in nature encompass a huge diversity of taxa. The extent of that diversity has emerged with the recent development of high throughput sequencing technologies that have revealed the existence of a very large number of rare microbial species in all ecosystems. This rare biosphere now starts to be better described both in its composition and functional attributes, and its ecology is slowly unveiled. Recent studies show that rare microbes can be separated into 3 main groups. Firstly, the local seed bank, also called conditionally rare microbes, that comprise dormant or little active taxa that are essential for seasonal ecosystem functioning. Secondly, the potential new colonizers that grow when dramatic changes occur in the ecosystem or that are passing by on their way to a more suitable substrate for growth. And thirdly, the rare but active microbes that play a key role in the ecosystem but that remain rare probably as a survival strategy. In this article, we explore these different aspects of rarity and review studies and approaches that have helped casting light on the rare biosphere.