Microbial Bioactives
Microbial Bioactives | Online ISSN 2209-2161
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Volume 6 Number 1 2023
REVIEWS (Open Access)
Life at the Edge: Marine Fungi and Microbial Resilience in Deep-Sea Hypersaline Anoxic Basins
Armania Nurdin 1*
Microbial Bioactives 6 (1) 1-8 https://doi.org/10.25163/microbbioacts.6110671
Submitted: 18 January 2023 Revised: 21 March 2023 Accepted: 28 March 2023 Published: 30 March 2023
Abstract
Deep-sea hypersaline anoxic basins (DHABs) are among the most extreme and least explored ecosystems on Earth, formed through the dissolution of ancient evaporitic deposits and characterized by permanent anoxia, extreme salinity, high hydrostatic pressure, and steep physicochemical gradients. Once considered inhospitable to life, these basins have emerged as natural laboratories for understanding the limits of biological adaptation. Over the past two decades, systematic investigations combining molecular surveys, microscopy, cultivation-based studies, and meta-analytical syntheses have revealed unexpectedly diverse and metabolically active microbial communities thriving at the brine–seawater interface. While prokaryotes initially dominated scientific attention, fungi are now recognized as integral components of DHAB ecosystems. These organisms exhibit remarkable physiological flexibility, enabling them to withstand osmotic stress, chaotropic salts, and limited water activity through specialized metabolic and regulatory mechanisms. Evidence synthesized from multiple DHAB systems, including basins in the Mediterranean and Red Sea, indicates that fungi play essential roles in organic matter degradation, nutrient remineralization, and carbon cycling under extreme conditions. The halocline, acting as a natural trap for sinking organic particles, provides a concentrated energy source that supports fungal growth and promotes interactions with chemoautotrophic prokaryotes. Beyond their ecological relevance, DHAB-associated fungi represent a largely untapped reservoir of novel enzymes and secondary metabolites with promising applications in biotechnology, medicine, and industry. This systematic synthesis highlights the ecological significance, adaptive strategies, and biotechnological potential of fungal communities in DHABs, underscoring their value for advancing our understanding of life at environmental extremes and for guiding future exploration of extreme marine habitats.
Keywords: Deep-sea hypersaline anoxic basins; extreme environments; marine fungi; halocline; polyextremophiles; blue biotechnology
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