The Influence of Host Specificity and Temperature on Bacterial Communities Associated with Sargassum (Phaeophyceae) Species

Abstract

Host-related microbiota are critically important for the adaptation/acclimation of hosts to changing environments, but how environmental factors and host characteristics shape the microbial communities remains largely unknown. We investigated the effects of temperature on habitat-forming macroalgae and their associated bacterial communities. Three Sargassum species (S. horneri, S. fusiforme, and S. thunbergii) and seawater samples were sampled in Gouqi Island, China, and these macroalgal samples were incubated at different temperatures (10, 20, and 27°C) for 7 d. Bacterial communities were identified from the 16S rRNA gene V3-V4 regions. The algae-associated bacterial communities of the field samples were significantly different from seawater, implying host specificity. During laboratory incubation, decreased physiological status (photosynthetic rate and oxidative stress response) was detected for all the species at 10°C, especially with regard to S. horneri and S. fusiforme. For each host, associated bacterial communities at 20 and 27°C clustered closely, and these were separated from samples at 10°C based on constrained PCoA analyses. Permutational multivariate analysis of variance revealed that algae-associated bacterial communities were more affected by host species (23.3%) than by temperature (2.48%) during laboratory incubation. The changes in bacterial community composition may be influenced by algae metabolites, which should be tested in a future study. These results further contribute to our understanding of algal microbiome changes in response to environmental changes.

Microbiome changes in a stranding simulation of the holopelagic macroalgae Sargassum natans and Sargassum fluitans

“…Previous studies have reported species, morphology and biogeography as sources of microbial variations in holopelagic Sargassum species [16,17,61]. However it is unlikely that the environmental water column microbiome itself could affect our results, since water and macroalgal microbiomes are shown to differ greatly [16,22,62].…”

Unveiling the culturable and non‐culturable actinobacterial diversity in two macroalgae species from the northern Portuguese coast

“…Interestingly, these groups were not isolated through cultivation efforts. While previous studies on macroalgae microbiome have reported that both Gram‐negative and Gram‐positive communities exhibit host‐specificity (Kuba et al, 2021; Li et al, 2022; Sanders‐Smith et al, 2020), they have also highlighted that the structure of bacterial communities is more likely associated with functional genes rather than taxonomy (Morrissey et al, 2019; Roth‐Schulze et al, 2018). Though we have detected a higher abundance of Actinomycetota in C. crispus (Figure 6), the most representative groups within this phylum were the same in both macroalgae.…”

Methylphosphonate Is Utilized by Commensal Microbiota of Macroalgae in the Oligotrophic Sargasso Sea

“…Li et al. (2022) found that community composition of bacterial epiphytes on rooted Sargassum species varied with host species and, to a lesser extent, temperature. Additionally, phnP genes were enriched by amendments of vitamins and methanol similar to amendments of HMWDOM (Gifford et al., 2016), indicating additional factors influencing MPn apart from phosphate availability.…”

“…Contributions from other macroalgal species, or even biogeographic and temporal effects acting on Sargassum, may drive additional flux, and we further note that the highest observed production rate (for D. baillouviana) was ∼14-fold greater than the rate used for these calculations. Li et al (2022) found that community composition of bacterial epiphytes on rooted Sargassum species varied with host species and, to a lesser extent, temperature. Additionally, phnP genes were enriched by amendments of vitamins and methanol similar to amendments of HMWDOM (Gifford et al, 2016), indicating additional factors influencing MPn apart from phosphate availability.…”