11:45 〜 12:00
[MIS17-10] プラスチックごみは本当に微生物を運搬するか？
キーワード：プラスチックごみ、プラスティスフェア、メタゲノム解析
Approximately 1,150 million tons of plastics are flown into the ocean per year based on the current estimation. These plastic debris are downsized to micro- to nano-levels, and then drift through ocean gyre and/or sink to deep seafloor. The plastic debris attract our attention, because they are ingested by marine organisms. However, these plastic debris involve unexpected roles for microorganisms as new habitats. The rapid colonization of microbiome on plastic debris makes “Plastisphere”. These plastisphere microbiome could be spread over the ocean and sink down to the deep seafloor. Since the plastic-drifters have already spread over the world during the past 50 years, it is difficult to assess the ecological dispersion by the plastic debris.
Here, we propose that microbiomes hitchhike on plastic debris as a new dispersion path of microorganisms in the oceans. To test the hypothesis, we collected 30 plastic debris from three deep seafloor stations (BHT: 35.00N, 139.13E, 855 m water depth; BMS: 35.04N, 139.32E, 755 m water depth; and BSG: 35.00N, 139.22E, 1,400 m water depth) in Sagami Bay. The polymer compositions of 30 plastic debris were different each other (polyethylene, polyethylene terephthalate, polystyrene, and polypropylene). We compared 16S rRNA sequences of these 30 plastisphere microbiomes with newly constructed 16S rRNA sequence database derived from sediments and water columns in global ocean, collected from the public database (NCBI). From the oceanic 16S rRNA database, 27% operational taxonomic units (OTUs) collected from plastic debris in Sagami Bay have global distribution in sediments and water columns. With network analysis of the widely-distributed microorganisms on plastic debris in Sagami Bay, spatial difference is more important than material difference. Even the material difference is not a primary controlling factor, 18% of OTUs having global distribution show material preference. These material specific microbes are possibly drifted by plastic debris, and spread their distribution all over the ocean. These results indicate that ecological impact of plastic debris in the ocean should be revisited with its extent of ecological drift for oceanic microorganisms.
Here, we propose that microbiomes hitchhike on plastic debris as a new dispersion path of microorganisms in the oceans. To test the hypothesis, we collected 30 plastic debris from three deep seafloor stations (BHT: 35.00N, 139.13E, 855 m water depth; BMS: 35.04N, 139.32E, 755 m water depth; and BSG: 35.00N, 139.22E, 1,400 m water depth) in Sagami Bay. The polymer compositions of 30 plastic debris were different each other (polyethylene, polyethylene terephthalate, polystyrene, and polypropylene). We compared 16S rRNA sequences of these 30 plastisphere microbiomes with newly constructed 16S rRNA sequence database derived from sediments and water columns in global ocean, collected from the public database (NCBI). From the oceanic 16S rRNA database, 27% operational taxonomic units (OTUs) collected from plastic debris in Sagami Bay have global distribution in sediments and water columns. With network analysis of the widely-distributed microorganisms on plastic debris in Sagami Bay, spatial difference is more important than material difference. Even the material difference is not a primary controlling factor, 18% of OTUs having global distribution show material preference. These material specific microbes are possibly drifted by plastic debris, and spread their distribution all over the ocean. These results indicate that ecological impact of plastic debris in the ocean should be revisited with its extent of ecological drift for oceanic microorganisms.