Summary of main content: Global warming alters the gut microbiota of Pacific whiteleg shrimp by restructuring enterotypes, increasing the risk of diseases such as white feces syndrome (WFS) and hepatopancreatic necrosis syndrome. This study identifies temperature as the primary driver of microbial structure and proposes "enterotypes" as a key ecological indicator to predict the health of poikilothermic animals in the context of climate change.
1. Introduction
With modern industrialization and urbanization, global warming has become a serious threat to ecosystems, especially affecting poikilothermic animals (species whose body temperature depends on the environment) such as fish and shrimp. Unlike mammals, poikilothermic animals are extremely sensitive to temperature changes, which affects their distribution, behavior, physiology, metabolism, and immune function.
One of the most affected systems is the intestinal microbiota (IM). IM is a sensitive indicator of temperature changes and plays a crucial role in the host's metabolism and immune processes.
To better understand the changes in IM, microbial communities are often classified into distinct types called "enterotypes" – groups of microbial components dominated by different key bacterial genera.
2. Study Subject: Pacific Whiteleg Shrimp (Litopenaeus vannamei)
Pacific whiteleg shrimp is a major aquaculture species, with production exceeding 5.6 million tons worldwide in 2022. However, it faces major disease threats such as:
Acute Hepatopancreatic Necrosis Disease (AHPND).
Hepatopancreatic Necrosis Syndrome (HPNS).
White Feces Syndrome (WFS). All are associated with gut microbiota dysbiosis. Notably, WFS outbreaks significantly increase at high temperatures (33 - 34°C).
3. Methods and Results
The study analyzed 1,369 IM samples from 15 shrimp cohorts in 9 major shrimp-producing countries (accounting for approximately 79.8% of global production).
Classification of 3 main Enterotypes:
ET V: Dominated by the genus Vibrio (predominant in samples affected by hepatopancreatic necrosis syndrome - HPNS).
ET S: Dominated by the genus Shewanella.
ET CB: Dominated by the genus Candidatus Bacilloplasma (predominant in samples affected by white feces syndrome - WFS).
Key findings:
Temperature is the most critical factor: Analysis showed that temperature contributed 26.9% to the formation of gut microbial structure, surpassing geographical factors.
Temperature-dependent changes: As temperature increased, Alpha diversity (Chao1 and Shannon indices) increased, but microbial interaction networks became less stable and less connected.
Controlled experiment: At 36°C, shrimp survival rates decreased and the microbiota shifted significantly towards the ET CB (Candidatus Bacilloplasma) enterotype.
Gene analysis: Transcriptomic analysis revealed 2,276 differentially expressed genes (DEGs) in response to temperature, including antimicrobial peptides (PENs, ALFs) associated with microbial changes.
4. Discussion and Conclusion
The study emphasizes that increasing temperature alters the gut microbial composition of shrimp by restructuring enterotypes, thereby increasing the likelihood of disease outbreaks such as WFS and EMS (Early Mortality Syndrome).
Vibrio / Candidatus Bacilloplasma ratio: Considered a crucial ecological indicator closely linked to enterotypes and health status.
Regional impact: Warmer regions like Thailand and China showed greater diversity in enterotype distribution, whereas regions with narrower temperature ranges like Brazil exhibited only one enterotype (ET V).
Resilience: High temperatures reduced the resilience of the microbial system, creating conditions for opportunistic pathogens to thrive.
Call to action: With white feces syndrome (WFS) spreading to higher latitude regions in recent years, the study calls for immediate preventive strategies in aquaculture to mitigate risks caused by climate change. Shrimp enterotypes can serve as valuable ecological indicators to monitor the impact of global warming on poikilothermic animals.
Summary source from the article by the author group: Zeng, S. and Huang, Z. (Sun Yat-sen University, China) and colleagues from Thailand and the network of aquaculture centers in Asia-Pacific.
