Bacterial microbiome variation across symbiotic states and clonal lines in a cnidarian model

Abstract

IntroductionExaiptasia diaphana is a popular model organism for exploring the symbiotic relationship observed between cnidarians and their microsymbionts. While physiological roles of algal photosymbionts (Symbiodinaceae) are well studied, the contributions of bacterial communities are less defined in this system.MethodsWe investigated microbial variation between distinct parts of the body and symbiotic state across four genets held in identical environmental conditions using 16s rRNA gene amplicon sequencing.ResultsWe found differentially abundant taxa between body part and symbiotic state that highlight the roles these bacteria may play in holobiont heterotrophy and nutrient cycling. Beta-diversity analysis revealed distinct communities between symbiotic states consistent with previous studies; however, we did not observe the presence of previously reported core microbiota. We also found community differences across clonal lines, despite years of identical rearing conditions. ConclusionThese findings suggest the Exaiptasia bacterial microbiome is greatly influenced by host genetics and unpredictable environmental influences.

Abundance of Oligoflexales bacteria is associated with algal symbiont density, independent of thermal stress in Aiptasia anemones

“…We observed a significant difference in the relative abundance of Oligoflexales, Saccharospirillaceae, Pseudoalteromonadaceae, and Methylophilaceae families between symbiotic and aposymbiotic animals, with these taxa being more prevalent in the former (Figure 4b). Our findings align with other studies that have demonstrated differences in relative abundance of microbiome composition between aposymbiotic and symbiotic states in strain CC7 (Curtis et al, 2023;Röthig et al, 2016;Sydnor, 2020). Nevertheless, the four differentially abundant taxa we identified were not previously reported, suggesting genotype by environment and symbiotic state all influence microbial assemblages in Aiptasia.…”

“…from the Oceanospirillales order, Cognatishimia sp., and an unclassified bacterium from the Rhodobacteraceae family from the Rhodobacterales order accounted for around 60%-85% of the total relative abundance (Figure S2). This observation, that 2-3 taxa are numerically dominant in Aiptasia, contradicts other microbial surveys on Aiptasia that identified a wider range of taxonomic groups within the same relative abundance range (Curtis et al, 2023;Randle et al, 2020;Röthig et al, 2016). The importance of functional redundancy in shaping microbial communities in Aiptasia is emphasized by the conflicting results obtained from various studies.…”

Abundance of Oligoflexales bacteria is associated with algal symbiont density independent of thermal stress in Aiptasia anemones

“…3b). Our findings align with other studies that have demonstrated differences in relative abundance of microbiome composition between aposymbiotic and symbiotic states in strain CC7 (Röthig et al, 2016;Sydnor, 2020;Curtis et al, 2023). Nevertheless, the four differentially abundant taxa we identified were not previously reported, suggesting genotype by environment and symbiotic state all influence microbial assemblages in Aiptasia.…”

“…A2). This observation, that 2-3 taxa are numerically dominant in Aiptasia, contradicts other microbial surveys on Aiptasia that identified a wider range of taxonomic groups within the same relative abundance range (Röthig et al, 2016;Randle et al, 2020;Curtis et al, 2023). The importance of functional redundancy in shaping microbial communities in Aiptasia is emphasized by the conflicting results obtained from various studies.…”

The bacterial microbiome of symbiotic and menthol-bleached polyps of long-term aquarium-rearedGalaxea fascicularis

“…The stochastic response to bleaching aligns well with the concept of an obligatory nature of the coral-algal symbiosis. In facultatively symbiotic cnidarians (such as the anemone Aiptasia), symbiotic and bleached can constitute alternative stable states, and it is thus possible to identify distinct and characteristic symbiotic and bleached microbiome configurations (Röthig et al 2016; Curtis et al 2023). Corals however depend on their algal symbiont for energy and other essential metabolic processes (Muscatine and Porter 1977; Muscatine 1990), and therefore the bleached state is not a stable alternative to the symbiotic state.…”