Bacterial Community Analysis of Captive Marine Mammals Pool Water using Next-Generation Sequencer

海棲哺乳類の排泄物は海洋環境において重要な栄養源となっているが，飼育下の海棲哺乳類はその水質によって健康を損なう可能性がある。本研究ではその水質に着目し，細菌の群集解析を行うことで，それぞれの動物種の飼育水の細菌学的特徴を明らかにすると共に感染症を引き起こす原因菌のスクリーニングを行うことを目的とした。おたる水族館で飼育されている鰭脚類と鯨類を含む計10の飼育水と元の海水について次世代シークエンサにて細菌の塩基配列を調べ，細菌の群集解析を行った。その結果，飼育水の特徴としては，Proteobacteria，Bacteroidetes，Firmicutesが元海水と共通して見られたが，FusobacteriaおよびOD1・GNO2といった培養不能細菌門は飼育水に特徴的であった。各動物の飼育水細菌叢は鯨類や鰭脚類においてそれぞれ特徴的であったが，鰭脚類においてワモンアザラシは他との類似性が低かった。飼育水には環境中に存在する日和見菌がわずかに見つかったが，伝染性細菌やその他公衆衛生上特に注意すべき細菌は認められなかった。今後，他の水族館の飼育水についても調べることで，より理想的な海棲哺乳類の飼育環境づくりに繋がることが期待される。Eye disorders is a life-threatening for pinnipeds, such as sea lions and seals, that are rely on vision for feeding. It is suspected that such as ultraviolet light, trauma on cornea and water quality may causes of ophthalmological diseases for marine mammals. In this study, we focused on the water quality, to conduct comprehensive analysis of bacteria, to clarify the bacteriological characteristics of each animal pool waters in aquarium and to search for the cause bacteria of eye disease. Bacterial 16s rRNA was investigated using a next-generation sequencer to perform community analysis of pool waters of pinnipeds and cetaceans in Otaru Aquarium. As a result, there were few opportunistic but cause bacteria of eye disease, such as Staphylococcus aureus, Serratia or Welsh bacteria. Other infectious bacteria were not recognized that those are directly cause of some diseases or other bacterial infection in public health. Three bacterial phyla were found in common with the former seawater, such as Proteobacteria, Bacteroidetes, and Firmicutes, but Fusobacteria and some non-culturable bacteria were characteristic of animal pool waters. In addition, it was found that the composition of the bacteria is different depending on each animal, so that the bacterial flora may be affected by each animal excretion. So, it is necessary to survey the bacterial flora of pool water, but important to take measures to prevent damage on the cornea of captive marine mammals, which will be an invasion route of bacteria