10:00 〜 10:15
[AOS17-05] Fungi in deep-sea submerged plant substrates: Essential players in marine ecosystems
キーワード：深海生菌類、沈木、生物学的炭素ポンプ
Fungi are the main decomposers of plants on land, and it is also presumed that fungi play an important role in the decomposition of sunken plants in deep-sea environments. However, the diversity, distribution, and ecology of deep-sea fungi associated with sunken plant substrates remain largely unknown. To date, only six species of obligate deep-sea fungi that form fruiting bodies on sunken wood have been reported.
In this study, 21 samples (19 deep-sea sunken plants, 1 deep-sea sunken seaweed, and 1 shallow water sunken plant) were collected from 5 different sites (shallow water depth: 5m, deep-sea water depths: 720–5,707m) in the Western Pacific Ocean near Islands of Japan, to investigate the diversity and distribution of fungi related to deep-sea sunken plant substrates. Fungal amplicon analysis was performed on the samples by targeting the ITS rRNA gene region.
As a result, fungal fruiting bodies were observed on one sunken wood sample collected at a depth of 5,707 m. This fungus was identified as a novel species, Oceanitis abyssalis, closely related to Oceanitis scuticella, one of the obligate deep-sea fungi. Although fungal ascomata were not observed in any other samples, amplicon analysis detected sequences with high homology to Oceanitis spp. in eight samples collected from different depths and sites. These findings suggest that Oceanitis spp. frequently inhabit sunken plant substrates in deep-sea environments.
Furthermore, sequences with high homology to Ceriosporopsis halima, a cosmopolitan shallow-water marine fungus known for its lignocellulose-decomposing ability, were predominantly detected in the sample collected from shallow water. Interestingly, sequences showing high homology (approximately 86% homology) to C. halima but presumed to belong to a different species were detected in four deep-sea samples. This suggests the presence of deep-sea species closely related to C. halima.
Our results indicate that many undiscovered obligate deep-sea fungi still exist, and that some, such as those in the genus Oceanitis, are distributed across a wide range of water depths, from the mesopelagic to the abyssal zone. As decomposers, fungi play a crucial role in marine ecosystems by breaking down organic matter, including phytoplankton and submerged plant material. Their contributions to the biological carbon pump and nutrient cycling underscore the importance of studying their diversity and ecological functions. Further comprehensive investigations into their diversity, distribution, physiology, and genomics will provide key insights into the adaptation, evolution, and ecological significance of deep-sea fungi.
In this study, 21 samples (19 deep-sea sunken plants, 1 deep-sea sunken seaweed, and 1 shallow water sunken plant) were collected from 5 different sites (shallow water depth: 5m, deep-sea water depths: 720–5,707m) in the Western Pacific Ocean near Islands of Japan, to investigate the diversity and distribution of fungi related to deep-sea sunken plant substrates. Fungal amplicon analysis was performed on the samples by targeting the ITS rRNA gene region.
As a result, fungal fruiting bodies were observed on one sunken wood sample collected at a depth of 5,707 m. This fungus was identified as a novel species, Oceanitis abyssalis, closely related to Oceanitis scuticella, one of the obligate deep-sea fungi. Although fungal ascomata were not observed in any other samples, amplicon analysis detected sequences with high homology to Oceanitis spp. in eight samples collected from different depths and sites. These findings suggest that Oceanitis spp. frequently inhabit sunken plant substrates in deep-sea environments.
Furthermore, sequences with high homology to Ceriosporopsis halima, a cosmopolitan shallow-water marine fungus known for its lignocellulose-decomposing ability, were predominantly detected in the sample collected from shallow water. Interestingly, sequences showing high homology (approximately 86% homology) to C. halima but presumed to belong to a different species were detected in four deep-sea samples. This suggests the presence of deep-sea species closely related to C. halima.
Our results indicate that many undiscovered obligate deep-sea fungi still exist, and that some, such as those in the genus Oceanitis, are distributed across a wide range of water depths, from the mesopelagic to the abyssal zone. As decomposers, fungi play a crucial role in marine ecosystems by breaking down organic matter, including phytoplankton and submerged plant material. Their contributions to the biological carbon pump and nutrient cycling underscore the importance of studying their diversity and ecological functions. Further comprehensive investigations into their diversity, distribution, physiology, and genomics will provide key insights into the adaptation, evolution, and ecological significance of deep-sea fungi.