Transbiome invasions of femtoplankton

Abstract

The results of ecological and phylogenetic studies of femtoplankton, the smallest size fraction of plankton formed by viruses and ultramicrobacteria (UMB), are overviewed to shed light on the problem of transbiome invasions by microbes. Phylogenetic lineages of viruses and UMB are shown to be associated with particular biomes, thus indicating infrequent transbiome transitions in the microbial world. An alternative hypothesis of widespread cross-colonization events requires a deeper analysis of the factors that form the barrier between biomes and are responsible for the adaptation of microorganisms to different environments.