Diel patterning in the bacterial community associated with the sea anemone Nematostella vectensis

Abstract

Microbes can play an important role in the physiology of animals by providing essential nutrients, inducing immune pathways, and influencing the specific species that compose the microbiome through competitive or facilitatory interactions. The community of microbes associated with animals can be dynamic depending on the local environment, and factors that influence the composition of the microbiome are essential to our understanding of how microbes may influence the biology of their animal hosts. Regularly repeated changes in the environment, such as diel lighting, can result in two different organismal responses: a direct response to the presence and absence of exogenous light and endogenous rhythms resulting from a molecular circadian clock, both of which can influence the associated microbiota. Here, we report how diel lighting and a potential circadian clock impacts the diversity and relative abundance of bacteria in the model cnidarian Nematostella vectensis using an amplicon‐based sequencing approach. Comparisons of bacterial communities associated with anemones cultured in constant darkness and in light:dark conditions revealed that individuals entrained in the dark had a more diverse microbiota. Overall community composition showed little variation over a 24‐hr period in either treatment; however, abundances of individual bacterial OTUs showed significant cycling in each treatment. A comparative analysis of genes involved in the innate immune system of cnidarians showed differential expression between lighting conditions in N. vectensis, with significant up‐regulation during long‐term darkness for a subset of genes. Together, our studies support a hypothesis that the bacterial community associated with this species is relatively stable under diel light conditions when compared with static conditions and that particular bacterial members may have time‐dependent abundance that coincides with the diel photoperiod in an otherwise stable community.

Contribution of Maternal and Paternal Transmission to Bacterial Colonization in Nematostella vectensis

“…In addition, sampling of different body regions (physa, mesenteries and capitulum) of the adult revealed a specific microbiota for each region, with specific dominance of spirochaetes bacteria within the capitulum ( Bonacolta et al, 2021 ). Also changes in the diet lighting cycle induced differences in composition and relative abundance in N. vectensis microbiome ( Leach et al, 2019 ). It has also been observed that different life stages (larva, juvenile, and adult) host specific microbiota ( Mortzfeld et al, 2016 ; Domin et al, 2018 ).…”

The Rhythm of Many: Biological Rhythms in the Marine Environment, From Macro-Scale Planktonic Ecosystems to Micro-Scale Holobionts

“…Mice and human hosts rely on the daily relative abundance fluctuations of around 20% of their total microbiome species (Thaiss et al, 2014). However, under circadian disruption, these delicate gut microbial community compositions are significantly altered, leading to weakened immune defenses and holobiont health decline (Voigt et al, 2016;Deaver et al, 2018;Leach et al, 2019). Specifically, in the absence of rhythmic bacterial abundance fluctuations, hosts exhibit increased susceptibility to disease and decreased metabolomic output (Leone et al, 2015;Montagner et al, 2016;Thaiss et al, 2016).…”

Microbiota mediated plasticity promotes thermal adaptation inNematostella vectensis

“…Alphaproteobacteria and Gammaproteobacteria constitute main microbial colonizers of corals 57,65 and of N. vectensis 18,66 . The increased thermal tolerance of animals acclimated at high temperatures is often associated with an increase in abundance of these bacterial classes in the associated microbiota 67,68 .…”