Schedule > Guests

Microbes under stress: importance of interactions in their resilience

Eric Fouilland (CNRS-MARBEC)

It is generally accepted that microorganisms present in environments subject to severe chemical or biological constraints, such as eutrophication, the presence of toxic compounds or the presence of predators, are those that seem best adapted to these conditions. It is assumed that they possess, for example, a strong affinity for nutrients, high tolerance to toxins or efficient defense mechanisms. However, recent studies have highlighted the crucial role of interactions between these microorganisms, such as bacteria and phytoplankton, in the ability of microbial communities to withstand these constraints.

In particular, our research has revealed that in ecosystems that have been severely chemically disturbed, phytoplankton colonization only occurs through the development of opportunistic, stress-resistant pioneer species. These pioneer species then modify the chemical environment, facilitating the subsequent establishment of other phytoplankton species initially more sensitive to stress. Similarly, we have observed that the presence of bacteria can reduce the toxicity of chemical compounds, such as pesticides or metals, on the growth of microalgae.

These experimental observations suggest that intense positive interaction between certain microbial species can occur under particularly unfavorable conditions. These interactions seem to guarantee the survival of all the micro-organisms involved.

The coral microbiome: A glimmer of hope for corals in the Anthropocene (visio)

Amin Mohamed (New York University Abu Dhabi)

Coral reefs are the Earth's most diverse marine ecosystems, providing a habitat for a third of all marine species. These ecosystems are facing unprecedented threats from global anthropogenic impacts such as global warming and local stressors. This resulted in the loss of about half of the coral reef cover since 1950. Corals engage in symbiosis with a diverse community of bacteria, archaea, viruses, and eukaryotic microorganisms, known as the microbiome. Recent research has established the microbiome's pivotal role in coral survival and stress resilience. However, climate change can break down these symbiotic relationships, resulting in disease, bleaching, and coral death. In this talk, I will try to provide an overview of the complexity of the coral microbiome, focusing on taxonomic diversity and functions of well-studied and cryptic microbes, summarize the known mutualistic and antagonistic interactions between corals and their associated microbiomes, and discuss the impact of climate change on these communities.

I will highlight recent advances in coral microbiome research aimed at leveraging microbiome manipulation to increase coral's fitness to help mitigate climate change-driven mortality. Finally, I will show the promise ‘omics data may hold to study coral microbiomes, emphasizing the integrated host–microbiota multiomics framework for understanding the molecular mechanisms during symbiosis and climate change-driven dysbiosis.