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

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.

本研究通过对细菌16S rRNA基因（16S rRNA gene）片段的V4高变区（V4 hyper-variable region）开展带标签焦磷酸测序（barcoded pyrosequencing）分析，探究不同红树植物物种（Avicennia schaueriana与Laguncularia racemosa）与红树林潮间带沉积物中特异性细菌群落的关联程度。本研究选取与A. schaueriana及L. racemosa存在特异性关联的操作分类单元（Operational Taxonomic Units，OTU）开展后续系统发育分析，并探讨了其推定的生态生理功能。本研究首次发现，作为巴西红树林常见树种的A. schaueriana与L. racemosa，其根系与沉积物细菌群落的细菌优势度提升、群落丰富度降低及群落组成偏移存在显著关联。此外，本研究证实梭菌属（Clostridium）与弧菌属（Vibrio）的类群与不同红树树种存在特异性关联。本研究结果为解析细菌功能群在植物-微生物互作、植物健康及红树林生态系统功能中的潜在生态角色提供了新的见解。