Bacterial diversity in relation to secondary production and succession on surfaces of the kelp Laminaria hyperborea

Abstract

Kelp forests worldwide are known as hotspots for macroscopic biodiversity and primary production, yet very little is known about the biodiversity and roles of microorganisms in these ecosystems. Secondary production by heterotrophic bacteria associated to kelp is important in the food web as a link between kelp primary production and kelp forest consumers. The aim of this study was to investigate the relationship between bacterial diversity and two important processes in this ecosystem; bacterial secondary production and primary succession on kelp surfaces. To address this, kelp, Laminaria hyperborea, from southwestern Norway was sampled at different geographical locations and during an annual cycle. Pyrosequencing (454-sequencing) of amplicons of the 16S rRNA gene of bacteria was used to study bacterial diversity. Incorporation of tritiated thymidine was used as a measure of bacterial production. Our data show that bacterial diversity (richness and evenness) increases with the age of the kelp surface, which corresponds to the primary succession of its bacterial communities. Higher evenness of bacterial operational taxonomical units (OTUs) is linked to higher bacterial production. Owing to the dominance of a few abundant OTUs, kelp surface biofilm communities may be characterized as low-diversity habitats. This is the first detailed study of kelp-associated bacterial communities using high-throughput sequencing and it extends current knowledge on microbial community assembly and dynamics on living surfaces.

Identification and Characterization of a Halotolerant, Cold-Active Marine Endo-β-1,4-Glucanase by Using Functional Metagenomics of Seaweed-Associated Microbiota

“…This is consistent with previous findings on the bacterial community associated in January 2007 with another Fucales species, Fucus vesiculosus, as this bacterial community appeared to be dominated by Alphaproteobacteria and Gammaproteobacteria species (20). Nonetheless, Bacteroidetes and Planctomycetes species are also relatively abundant on brown algal surfaces (20,43), and one might be surprised that our functional metagenomic screen yielded no loci identified as originating from these phyla. An explanation might be that our E. coli expression strain (Gammaproteobacteria) does not readily recognize gene promoters of Bacteroidetes and Planctomycetes species.…”

Crustose coralline algal species host distinct bacterial assemblages on their surfaces

“…Pairwise comparisons revealed that T. prototypum samples had significantly higher estimated species richness (1026.58 ± 610.00 OTUs) compared with H. boergesenii (196.08 ± 74.96 OTUs, Dunn's Method, Po0.05, Figure 2). Bacterial species richness increases with algal age for some algal species (Bengtsson et al, 2012). The high level of species richness found on the surface of T. prototypum may be related to the fact that this CCA species, unlike the others tested here, does not slough its surface cells (see supplementary material in Ritson-Williams et al, 2014) allowing for the development of a more mature bacterial community.…”

Climate Change Impacts on Seagrass Meadows and Macroalgal Forests: An Integrative Perspective on Acclimation and Adaptation Potential

“…Although macroalgae and seagrasses form habitats worldwide known as hotspots of biodiversity and production, we know little about the microbes in these ecosystems (Bengtsson et al, 2012), but see Clasen and Shurin (2015) for an ecosystem approach. The relative few microbial studies performed have focused almost exclusively on (epi-)bacterial communities associated to seagrasses and macroalgae, neglecting most other microbes (Bengtsson et al, 2012;Bockelmann et al, 2012Bockelmann et al, , 2013Michelou et al, 2013;Brakel et al, 2014Brakel et al, , 2017Cúcio et al, 2016;Singh and Reddy, 2016). On top of that, particularly functional interactions between marine macrophytes and their microbiomes are poorly known.…”