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) 1-17 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) remain among the most physically and chemically extreme habitats known in the marine environment, yet growing evidence suggests that these ecosystems are far more biologically dynamic than previously assumed. This review synthesizes current knowledge regarding fungal diversity, ecological functioning, and adaptive survival strategies within DHAB systems, with particular emphasis on the Mediterranean and Red Sea basins. Drawing from molecular surveys, cultivation-based investigations, microscopy, and meta-analytical interpretations, the study reveals that fungal communities are not merely transient occupants of these environments but active contributors to deep-sea ecosystem processes. The halocline consistently emerged as a biologically enriched transition zone where fungal abundance and diversity increase alongside organic matter accumulation and steep redox gradients. Fungi appear to persist through a combination of osmoregulatory mechanisms, stress-response pathways, and metabolic flexibility that enable survival under permanent anoxia, extreme salinity, and high hydrostatic pressure. Beyond ecological significance, DHAB-associated fungi also represent a promising yet largely unexplored reservoir of extremozymes and secondary metabolites with potential applications in biotechnology, pharmaceuticals, and industrial bioprocessing. Although methodological heterogeneity and limited geographic coverage still constrain interpretation, the collective evidence increasingly challenges long-standing assumptions that deep hypersaline systems are biologically marginal. Instead, DHABs emerge as critical natural laboratories for understanding microbial resilience, biogeochemical adaptation, and the broader limits of eukaryotic life under extreme environmental stress.
Keywords: Deep-sea hypersaline anoxic basins; extreme environments; marine fungi; halocline; polyextremophiles; blue biotechnology
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