Differential hypo-osmotic stress responses and regulatory mechanisms of Aspergillus sydowii in amphipod guts and hadal sediments

Author: mycolabadmin
10/29/2025
View Source

Summary

Scientists discovered a new fungus living in the guts of deep-sea amphipods and studied how it survives in extreme pressure and low-salt environments. By comparing this gut fungus with a similar fungus from deep-sea sediments, they found that the gut fungus is better adapted to low-salt conditions and produces different protective chemicals. The study reveals that fungi evolve different survival strategies depending on where they live, using changes in cell walls and energy production to handle environmental stress.

Background

Hadal amphipods inhabit extreme deep-sea environments and harbor gut microbiota that influence host physiology and environmental adaptation. While previous research on Aspergillus sydowii has focused on high-salinity stress responses, understanding of culturable gut fungi and their response to low-osmotic conditions remains limited, particularly regarding divergence in adaptive mechanisms across different fungal sources.

Objective

This study aims to investigate the physiological responses and regulatory mechanisms of Aspergillus sydowii isolated from hadal amphipod guts (XTO612) compared to a strain from hadal sediments (DM1) under hypo-osmotic stress conditions. The research seeks to elucidate habitat-driven evolutionary divergence in osmotic regulation mechanisms and secondary metabolite biosynthesis.

Results

Aspergillus sydowii XTO612 exhibited enhanced stress responsiveness under hypo-osmotic conditions, including increased sporulation (40% increase at 0.1 M NaCl) and faster metabolic recovery compared to DM1. Transcriptomic analyses revealed comprehensive regulatory strategies involving membrane permeability modulation, cell wall restructuring via upregulation of chitin synthase and mannose genes, enhanced energy metabolism pathways, and osmolyte biosynthesis. Ten distinct secondary metabolites were identified with differential expression between the two strains.

Conclusion

The study reveals divergent osmoregulatory strategies between conspecific marine fungal strains from different hadal habitats, demonstrating habitat-driven evolution of distinct osmotic regulation mechanisms. Hypo-osmotic stress significantly influences fungal cell wall remodeling, metabolic reprogramming, and secondary metabolite biosynthesis, providing foundational insights into fungal osmotic-response mechanisms with implications for biotechnology and understanding microbial strategies in extreme deep-sea environments.

Published in:Applied and Environmental Microbiology,
Study Type:Comparative Laboratory Study,
Source: PMID: 41159890