Ecological insights and potential application of marine filamentous fungi in environmental restoration

Marine ecosystem is a rich energy reservoir supporting diverse lifeforms. Filamentous fungi colonize various substrates of marine ecosystems in the form of saprotrophs, parasites and symbionts. Recent advancements in molecular methods unravelled diverse fungal communities dominating marine ecosystems, the majority of which belonged to genera Aspergillus, Penicillium, Trichoderma, Cladosporium and Fusarium of phylum Ascomycota. Prolonged exposure to hostile environments evolved marine fungi with adaptive mechanisms to tolerate high hygroscopic pressure, salinity, and temperatures. Besides, fungal symbiotic associations and biofilm formation over sessile substrate provide additional stability by facilitating nutritional balance and defence mechanisms. The synthesis of novel metabolites and extracellular enzymes shows the potential application in decomposition, mineralization, biomass production and nutrient cycling within marine ecosystems. Extracellular matrix (ECM) embedding fungal biofilm acts as a protective barrier against the hazardous effect of environmental pollutants. Coordinated expression of several catabolic genes such as lcc, LiP, MnP, CYP and enzymes regulate the degradation pathway of organic pollutants such as polycyclic aromatic hydrocarbons (PAHs), organochlorines, phthalates, and pharmaceuticals. Further, the presence of metal-chelating metallothionein (MT) gene, and dense mycelial mat within biofilm regulate biosorption and biotransformation of inorganic pollutants. The present article extensively comprehends the diversity and distribution of filamentous fungi associated with different parts of the marine ecosystem. Moreover, the role of filamentous fungi in pollutant remediation and application of gene-editing methods in developing genetically modified strains for enhanced remediation has been briefly discussed in the review.