Assessing variation in bacterial composition between the rhizospheres of two mangrove tree species

In this study, we determined to what extent different mangrove plant species (Avicennia schaueriana and Laguncularia racemosa) are associated with distinct bacterial communities in mangrove intertidal sediments using barcoded pyrosequencing analysis of bacterial 16S rRNA gene fragments (V4 hyper-variable region). Operational taxonomic units (OTUs) showing specific associations with A. schaueriana and L. racemosa were used in subsequent phylogenetic analysis and their putative ecophysiological roles are discussed. Our results show, for the first time, that root systems of A. schaueriana and L. racemosa (common tree species in Brazilian mangroves) are associated with increased bacterial dominance, lower richness and compositional shifts of sediment bacterial communities. In addition to this, we show that Clostridium and Vibrio populations show specific associations with different mangrove tree species. Our results shed new insight into the potential ecological roles of bacterial guilds in plant-microbe interactions, plant health and mangrove ecosystem functioning.