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Global warming is placing coral reefs around the world at increasing risk of severe bleaching. A research team led by Distinguished Research Fellow Sen-Lin Tang of Academia Sinica’s Biodiversity Research Center has found that a coral-associated bacterium can enhance tolerance to high temperatures and mitigate the physiological damage caused by heat stress.

Drawing on nearly a decade of research, the team built a comprehensive body of evidence spanning functionnal characterization of the bacterial strain, thermal tolerance experiments, multi-omics analyses, and single-cell transcriptomic analyses. The study not only confirms that the bacterium plays a protective role in corals, but also proposes a possible mechanism  underlying this protective effect, laying an important foundation for future development of probiotic-based coral conservation strategies. The findings were published in The ISME Journal in July 2026.

From a Promising Candidate to Proven Protection: Building a Complete Evidence Chain for Coral Probiotics

Healthy corals rely on symbiotic algae for most of their energy. When seawater temperatures rise, this relationship breaks down, causing corals to lose their symbiotic algae and bleach. Although bleached corals are not immediately dead, they become weaker and more vulnerable to disease and mortality. Improving coral heat tolerance is therefore a major focus of conservation and restoration research.

Tang explained that Endozoicomonas acroporae Acr-14ᵀ (Acr-14) is frequently found in healthy corals. Genomic analyses suggested that the bacterium play a role in nutrient cycling and antioxidant activity, helping corals cope with environmental stress. In 2020, the team was the first to show that Acr-14 can break down dimethylsulfoniopropionate, a compound produced by corals, and generate dimethyl sulfide, an antioxidant molecule also known as a climate-cooling molecule. This discovery resolved a hypothesis that had remained unconfirmed for more than two decades, but direct evidence that Acr-14 enhances coral heat tolerance was still lacking.

A major breakthrough of this study was the completion of a nearly decade-long effort to provide direct experimental evidence that Acr-14 enhances coral heat tolerance. This began with the successful isolation of Acr-14 from corals, work done in collaboration with Professor Wen-Ming Chen of National Kaohsiung University of Science and Technology. Comparative genomics, biochemical, and ecological analyses then revealed the bacterium’s strong antioxidant capacity, suggesting that it helps corals withstand heat stress. By overcoming the technical challenges of isolating, culturing, and reintroducing the bacterium into coral hosts, the researchers ultimately confirmed its protective effect against heat stress.

Single-Cell and Genomic Platforms Reveal How Coral Probiotics Enhance Heat Tolerance

To identify which coral cells respond to heat stress and probiotic treatment, first author Dr. Chih-Ying Lu and Assistant Research Fellow Yi-Jyun Luo introduced single-cell transcriptomic analysis. Working with Research Specialist Mei-Yeh Lu of the High-Throughput Sequencing Core Facility, they optimized coral tissue dissociation, cell preservation, and quality control to obtain high-quality samples for single-cell sequencing.

According to Chih-Ying Lu, the analysis identified 31 coral cell types and showed that Acr-14 helps stabilize the coral microbiome and reduce heat-induced microbial imbalance. Yi-Jyun Luo noted that integrating analyses of microbial communities, gene functions, and host single-cell gene expression enabled the team to examine host–microbe interactions at the cellular level and reveal how probiotics may help corals withstand heat stress. The team also generated a chromosome-level reference genome for a Taiwanese population of Stylophora pistillata, providing a valuable resource for single-cell and transcriptomic analyses and research on coral adaptation, host–microbe interactions, and climate change.

The study’s first author is Dr. Chih-Ying Lu, a postdoctoral researcher at Academia Sinica’s Biodiversity Research Center. Thecorresponding authors are Distinguished Research Fellow Sen-Lin Tang and Assistant Research Fellow Yi-Jyun Luo. Dr. Naohisa Wada of the Okinawa Institute of Science and Technology Graduate University also contributed to the research and provided expert guidance.

The study was supported by Academia Sinica and the National Science and Technology Council, with critical technical support from the Biodiversity Research Center’s High-Throughput Sequencing Core Facility.