マガキCrassostrea gigas幼生飼育水中の細菌相の変化について

• Main Authors: 雨村 明倫, 小西 達也, 沖増 英治
• Format: Report
• Language: Japanese
• Published: 報文 1996
• Subjects: Pacific; Crassostrea gigas; Pacific oyster
• Online Access: https://fukuyama-u.repo.nii.ac.jp/?action=repository_uri&item_id=7464; http://id.nii.ac.jp/1064/00007450/; https://fukuyama-u.repo.nii.ac.jp/?action=repository_action_common_download&item_id=7464&item_no=1&attribute_id=18&file_no=1

三倍体マガキ(C. gfgas)幼生の飼育水中から細菌の分離を行い,コロニーの色形状,グラム染色,生理的性質から,それらの細菌を8つのタイプ(W1,W2,W3,P,WS1,WS2,Y1,Y2)に分類した。飼育水中にはW1の数が多いものの,これらの細菌は比較的バランス良く棲息しており,幼生の生育に悪い影響は与えなかった。飼育水中の細菌相をコントロールする目的でストレプトマイシンを添加すると,細菌種がやや減り,W1が飼育後期に優先的に繁殖してきたが幼生の発育には全く影響がなかった。一方,エルバージュを添加した場合,飼育期間中W2のみが他の細菌を抑えて圧倒的に繁殖し,幼生の発育が抑えられ,幼生のほとんどが死滅してしまった。これらのことから飼育水中には有益あるいは無害な細菌がバランス良く生育していることが必要で,そのことが有害な細菌の繁殖を抑えていることが示唆された。 Colony types of bacteria isolated from the rearing water of Pacific oyster (C. gigas) larvae were classified into eight(W1, W2, W3, WS1, WS2, P, Y1, Y2) on the basis of their color, shape, gram staining and physiological properties. Bacteria with type W1 colony were found preferentially in the water during the whole period of rearing, and other types of bacteria appeared in large numbers in the first or latter half of the rearing period. However, looked as a whole, these bacteria are present in well-balanced proportion in the rearing water and did not give a bad effect on the growth of larvae. When streptomycin was added to the rearing water to control the bacterial flora, W1 type of bacteria predominated at the latter stage of the culture, but the oyster larvae grew well under this condition. Addition of sodium nifurstyrenate decreased the growth of most types of bacteria significantly, however, only bacteria with colony type W2 predominated in the rearing water, resulting in bad growth of the larvae and leading them to death. These results suggest that the balanced growth of useful or harmless bacteria for larvae prevents the preferential growth of harmful bacteria in the rearing water.