Relative stability of the Pocillopora acuta microbiome throughout a thermal stress event

Epstein, Hannah E.; Torda, Gergely; Oppen, Madeleine J. H. van

doi:10.1007/s00338-019-01783-y

Cited by 52 publications

(107 citation statements)

References 69 publications

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“…During a more recent coral bleaching events in Singapore, the coral genus Pocillopora appeared to show a shift to being less susceptible [12,35], similar to observationsfrom the Great Barrier Reef, Australia [36,37]. While this genus is known to be highly plastic [24,38,39], the mechanisms underlying its enhanced resistance to and ability to recover from thermal stress remain unclear.…”

Section: Introductionsupporting

confidence: 60%

Gene Expression and Photophysiological Changes in Pocillopora acuta Coral Holobiont Following Heat Stress and Recovery

et al. 2020

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The ability of corals to withstand changes in their surroundings is a critical survival mechanism for coping with environmental stress. While many studies have examined responses of the coral holobiont to stressful conditions, its capacity to reverse responses and recover when the stressor is removed is not well-understood. In this study, we investigated among-colony responses of Pocillopora acuta from two sites with differing distance to the mainland (Kusu (closer to the mainland) and Raffles Lighthouse (further from the mainland)) to heat stress through differential expression analysis of target genes and quantification of photophysiological metrics. We then examined how these attributes were regulated after the stressor was removed to assess the recovery potential of P. acuta. The fragments that were subjected to heat stress (2 °C above ambient levels) generally exhibited significant reduction in their endosymbiont densities, but the extent of recovery following stress removal varied depending on natal site and colony. There were minimal changes in chl a concentration and maximum quantum yield (Fv/Fm, the proportion of variable fluorescence (Fv) to maximum fluorescence (Fm)) in heat-stressed corals, suggesting that the algal endosymbionts’ Photosystem II was not severely compromised. Significant changes in gene expression levels of selected genes of interest (GOI) were observed following heat exposure and stress removal among sites and colonies, including Actin, calcium/calmodulin-dependent protein kinase type IV (Camk4), kinesin-like protein (KIF9), and small heat shock protein 16.1 (Hsp16.1). The most responsive GOIs were Actin, a major component of the cytoskeleton, and the adaptive immune-related Camk4 which both showed significant reduction following heat exposure and subsequent upregulation during the recovery phase. Our findings clearly demonstrate specific responses of P. acuta in both photophysiological attributes and gene expression levels, suggesting differential capacity of P. acuta corals to tolerate heat stress depending on the colony, so that certain colonies may be more resilient than others.

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Section: Introductionsupporting

confidence: 60%

Gene Expression and Photophysiological Changes in Pocillopora acuta Coral Holobiont Following Heat Stress and Recovery

et al. 2020

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“…4). Note that the absence of overall changes in the bacterial microbiome composition does not preclude the occurrence of changes in a small number of taxa and/or an increase or decrease in alphadiversity, as is commonly seen during thermal stress that does not lead to overt bleaching 68,69,71 ( Fig. 4).…”

Section: [H2] Warming Bleaching and Dysbiosismentioning

confidence: 99%

“…Few studies include pre-bleaching samples, but if bacterial community composition was examined prior to visual signs of bleaching, microbiome changes preceded bleaching 64 . Heat stress that does not result in bleaching generally is associated with overall microbiome stability 65,66,[69][70][71][72] (Fig. 4).…”

Section: [H2] Warming Bleaching and Dysbiosismentioning

confidence: 99%

“…Such subtle changes may represent an acclimatory response that leads to a slightly altered microbiome that is better able to function under the thermal stress conditions compared to the original bacterial community. The maintenance of a relatively stable microbiome may be indicative of a thermally tolerant holobiont 65,66,69 .…”

Section: [H2] Warming Bleaching and Dysbiosismentioning

confidence: 99%

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Coral microbiome dynamics, functions and design in a changing world

2019

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Corals associate not only with dinoflagellates, which are their algal endosymbionts and which have been extensively studied over the past four decades, but also with a diversity of other microbes. The coral microbiome includes the dinoflagellates, viruses, fungi, archaea and bacteria, with knowledge of the last growing rapidly. This Review focuses on the bacterial members of the coral microbiome and draws parallels with better-studied microbiomes in other biological systems. We synthesize current understanding of spatial, temporal and host-specific patterns in coral-associated bacterial communities, the drivers shaping these patterns and the role of the microbiome in acclimatization and adaptation of the host to climate warming. We discuss how this knowledge can be harnessed to assist the future persistence of coral reefs and provide novel perspectives for the development of microbiome engineering and its implications for coral reef conservation and restoration.

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“…Microbiome engineering through the addition of probiotics has been postulated as a key strategy to manipulate host phenotypes and ecosystem functioning for coral reefs [23][24][25][26][27][28]. The differences in the bacterial species composition of healthy and thermally stressed corals [29][30][31][32][33][34] and the coral model Exaiptasia diaphana [35][36][37] suggest a role for microbiome engineering in cnidarian health. A disruption to the bacterial community of Pocillopora damicornis with antibiotic treatment diminished the resilience of the holobiont during thermal stress, whereas intact microbial communities conferred resilience to thermal stress and increased the rate of recovery after bleaching events to the coral holobiont [38].…”

Section: Introductionmentioning

confidence: 99%

Development of a free radical scavenging probiotic to mitigate coral bleaching

Dungan

Bulach²,

Lin

et al. 2020

Preprint

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ABSTRACTCorals are colonized by symbiotic microorganisms that exert a profound influence on the animal’s health. One noted symbiont is a single-celled alga (from the family Symbiodiniaceae), which provides the coral with most of its carbon. During thermal stress, the algae’s photosystems are impaired, resulting in a toxic accumulation of reactive oxygen species (ROS) that cause cellular damage to both the host and symbiont. As a protective mechanism the coral host and algal symbiont disassociate; this process is known as bleaching. Our goal was to construct a probiotic comprised of host-associated bacteria able to neutralize free radicals such as ROS. Using the coral model, the anemone Exaiptasia diaphana, and pure bacterial cultures isolated from the model animal, we identified six strains with high free radical scavenging ability belonging to the families Alteromonadaceae, Rhodobacteraceae, Flavobacteriaceae, and Micrococcaceae. In parallel, we established a “negative” probiotic consisting of genetically related strains with poor free radical scavenging capacities. From their whole genome sequences, we explore genes of interest that may contribute to the potential beneficial roles of these putative probiotic members, which may help facilitate the therapeutic application of a bacterial probiotic. Probiotics is one of several interventions currently being developed with the aim of augmenting climate resilience in corals and increasing the likelihood of coral reef persistence into the future.IMPORTANCECoral bleaching is tightly linked to the production of reactive oxygen species (ROS), whereby ROS accumulates to a toxic level in host-harboring algae cells leading to coral-algal dysbiosis. Interventions targeting toxic ROS accumulation, such as the application of exogenous antioxidants, have shown promise for maintaining the coral-algal partnership. With the feasibility of administering antioxidants directly to corals low, we have applied bioengineering strategies to develop a probiotic to neutralize toxic ROS during a thermal stress event. This probiotic can then be tested with corals or a coral model to assess its efficacy in improving coral resistance to environmental stress.

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Relative stability of the Pocillopora acuta microbiome throughout a thermal stress event

Cited by 52 publications

References 69 publications

Gene Expression and Photophysiological Changes in Pocillopora acuta Coral Holobiont Following Heat Stress and Recovery

Gene Expression and Photophysiological Changes in Pocillopora acuta Coral Holobiont Following Heat Stress and Recovery

Coral microbiome dynamics, functions and design in a changing world

Development of a free radical scavenging probiotic to mitigate coral bleaching

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