The HOG signal pathway contributes to survival strategies of the piezo-tolerant fungus Aspergillus sydowii DM1 in hadal sediments

Author: mycolabadmin
8/12/2025
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Summary

Scientists discovered a special deep-sea fungus from the Mariana Trench (nearly 7 miles deep) and studied how it survives extreme pressure and harsh conditions. By examining its DNA and turning off a specific gene called hog1, they found this gene is crucial for the fungus to handle stress and produce energy. Understanding how this deep-sea fungus adapts could help us develop stronger microorganisms for various applications and better understand how life survives in Earth’s most extreme environments.

Background

The hadal zone (>6,000 m ocean depth) represents one of Earth’s most extreme ecosystems, characterized by high hydrostatic pressure, low temperature, and limited nutrients. Deep-sea fungi play critical roles in geochemical cycling and marine ecosystem functioning, yet research on their cultivable strains and adaptive mechanisms remains scarce. This study focuses on Aspergillus sydowii DM1, a piezo-tolerant fungus isolated from the Mariana Trench at 10,898 m depth.

Objective

To comprehensively analyze the genome of A. sydowii DM1 and investigate the functional role of the HOG (high-osmolarity glycerol) signal pathway in fungal adaptation to hadal environmental conditions. The study aimed to develop genetic manipulation tools for marine filamentous fungi and elucidate the molecular mechanisms underlying high hydrostatic pressure tolerance.

Results

The genome of A. sydowii DM1 comprises 34.5 Mb with 12,241 predicted genes, containing complete metabolic pathways for carbohydrate, amino acid, sulfur, and nitrogen metabolism. The ΔAshog1 mutant displayed reduced spore production, altered secondary metabolite profiles, and significantly impaired oxidative stress tolerance. Ashog1 regulated reactive oxygen species (ROS) and ATP levels in response to osmotic pressure and high hydrostatic pressure, with ROS levels 5-6 fold higher in the knockout strain across all conditions.

Conclusion

The HOG signal pathway plays a crucial role in stress response and metabolic regulation of hadal fungi, particularly in managing ROS accumulation and energy metabolism under high hydrostatic pressure. This study demonstrates the first successful gene knockout in a hadal filamentous fungus and reveals previously unexamined HOG pathway functions in extreme pressure adaptation, advancing understanding of microbial survival mechanisms in the hadal zone.

Published in:Applied and Environmental Microbiology,
Study Type:Experimental Research,
Source: 10.1128/aem.00921-25, PMID: 40793769