Summer shifts of bacterial communities associated with the invasive brown seaweed Sargassum muticum are location and tissue dependent

Abstract

Seaweed-associated microbiota experience spatial and temporal shifts in response to changing environmental conditions and seaweed physiology. These shifts may result in structural, functional and behavioral changes in the host with potential consequences for its fitness. They, thus, may help the host to adapt to changing environmental conditions. The current knowledge of seasonal variation of seaweed-associated microbiota is however still limited. In this study, we explored temporal and spatial variation of microbial communities associated with the invasive brown seaweed S. muticum. We sampled in northern and southern Portugal, in September, March and July-August (summer). In addition, as (pseudo-)perennial seaweeds display seasonal reproductive phenology, we sampled various parts of the individuals to disentangle the effect of temporal changes from those due to structural development variations. The diversity and structure of associated microbial communities were determined using next generation sequencing of the variable regions V5-7 of the 16S rDNA. We expected to find differentiation in associated microbial communities between regions and sampling months, but with differences depending on the seaweed structure examined. As expected, the study revealed substantial temporal shifts in S. muticum microbiome, for instance with large abundance of Rhodobacteraceae and Loktanella in September-March but prevalence of Pirellulales during the summer months. Variations between regions and tissues were also observed: in northern Portugal and on basal structures, bacterial diversity was higher as compared to the South and apical parts. All examined seaweed structures showed temporal differences in associated microbial community structure over time, except for holdfasts between September and March. Bacteria contributing to these changes varied spatially. Conversely to all other structures, the holdfast also did not show differences in associated community structure between southern and northern regions. Our study highlights the importance of structural microscale differentiations within seaweeds hosts with regard to their associated microbial communities and their importance across temporal and spatial dimensions.

A Multi-Omics Analysis Suggests Links Between the Differentiated Surface Metabolome and Epiphytic Microbiota Along the Thallus of a Mediterranean Seaweed Holobiont

“…α-Diversity metrics decreased from the basal to the apical parts of T. atomaria at both sites. Similar results have been previously reported for the Phaeophyceae Sargassum muticum for which the α-diversity of the bacterial communities is significantly higher at the holdfast in comparison to the tips (Serebryakova et al, 2018). By contrast, no significant differences have been determined for Fucus vesiculosus when comparing tips, thallus and the whole seaweed (Parrot et al, 2019).…”

Evaluation of a new primer combination to minimize plastid contamination in 16S rDNA metabarcoding analyses of alga‐associated bacterial communities

“…coli numbering system) and they designed the 799F primer that includes four mismatches with chloroplasts to amplify Bacteria while avoiding chloroplast amplification from maize roots (Chelius and Triplett, ). The resulting primer was then used in combination with primer 1193R (amplification product 394 bp) in several studies on bacterial communities associated with plants (Sagaram et al ., ; Bodenhausen et al ., ) or macroalgae (Vieira et al ., ; Aires et al ., ; Serebryakova et al ., ). However, this primer set still yielded up to 38% of sequences affiliated to chloroplasts (Sagaram et al ., ).…”

From the Sea to the Land: Dynamic of the Sargassum Tide Holobiont in the Caribbean Islands

“…Molecular studies of the microbial communities associated with Sargassum are relatively limited [25][26][27][28]49] and to our knowledge absent from near shore Atlantic coasts. Here, we uncover both the prokaryotes and the eukaryotic communities associated with 100 samples corresponding to Sargassum seaweeds from tide sites, the seawater surrounding stranded Sargassum or near-shore rafts, and to Sargassum seaweeds from inland storage sites.…”

“…Overall, our results show that the bacterial communities, which could be a mix of epiphytes and probably endophytes, associated with tide-associated Sargassum, are distinct from those in the surrounding seawater, con rming ndings previously obtained for various macroalgae (for Sargassum sp. see [25,26,28]).…”

“…More generally, microorganisms are likely to contribute to algae raft formation and maintenance, algae sinking and biodegradation upon beaching [23], and could provide important applications in the isolation of valuable compounds [24]. At molecular level, the bacterial diversity associated with genus Sargassum has been investigated in only a few locations [25][26][27][28], but neither the bacterial communities at tide sites nor the eukaryotic ones have ever been explored.…”