Deep-sea remains one of the most mysterious and unexplored extreme environments, holding great potential and interest for science. Since the first foray into deep-sea research, with the development of advanced instrumentation for sampling and researching, the presence and ecological importance of deep-sea bacteria and archaea has been extensively researched and well documented. In contrast, fungi, one of the most important components in earth ecosystems occupying a wide variety of environments by virtue of their highly versatile physiology function, have been relatively unexplored. However, the presence of fungi in deep-sea environments with their novelty and ecological importance in ecosystems is recognised with much interest in the last decade.

The isolation of deep-sea fungi was first reported in 1964 from the Atlantic Ocean at a depth of 4450m. Since this first reported incident, many fungi have been isolated and reported from various deep-sea environments, for example, the deepest sea of the Mariana Trench, hydrothermal vents, cold seeps, whale-falls, and deep marine subsurface. There are a few reports describing obligate marine fungi inhabiting the deep-sea, but most of the fungi reported by culture-independent methods from deep-sea environments are facultative fungi closely related to terrestrial species, while culture-independent methods often detect hidden fungal diversity belonging to the basal lineages.

In this presentation, the diversity of deep-sea fungi and their emerging ecological roles in environments will be discussed. In addition, the biotechnological potential of deep-sea fungi is also introduced. Fungi have long been known to produce a variety of industrial and medicinally useful substances. Recently deep-sea fungi have attracted much attention as a source of exploration for novel bioactive substances.