腸炎ピプリオの海底層別分布の検討

　腸炎ビブリオVibrio parahaemolyticusの底質における垂直分布状態、を知るために， 人工海底へ本菌を接種した実験，及び天然海底を垂直的に採泥した調査を行なった.その結果次のことが推定された.
(1) 本菌の生物1型菌は， 底質の表層部に棲息分布しても深層部lこは生存し難い.この傾向は砂質において特lこ強かった.従って，前報で使用した採泥器の性能に砂質で1型菌が高率に検出された.
(2) 生物2型菌は底質の砂・泥質にかかわらず，叉浅・深層に広く生存し得る.従って， 前報で2型薗が砂・泥質lこ広く検出された.
(3) 生物1型菌が棲息する所lこは2型菌も分布する傾向があった.
(4) 生物1型菌あるいは2型菌の生存とその環境底質のpH及び酸化還元電位とは，殆んど相関が認められなかった.
(5) 泥質は，砂質に較べ有機物や窒素源が多量に含まれていた.このことは，本菌の分布と重要な関係があるものと考えられた.

The present study was undertaken to investigate the distribution of Vibrio parahaemolyticus within columns of marine sediments in relation to the distance from the water-bottom interface. Both the laboratory experiment employing the 'artificial sea bottom' and the field survey in nearshore waters were conducted. The biotype 1 organisms of the bacteria were found only in the upper layers of the sediment in the case of sandy bottom, while their occurrence sometimes extended to somewhat deeper layers in the muddy bottom. The biotype 2 organisms inhabited both sandy and muddy bottom, ranging from water-bottom interface to a depth of 10 or 15 cm. It is therefore suspected that the tendency for the biotype 1 organisms to have been detected at high ratios from the sandy bottom, which was reported in the previous papers, was most probably due to the functional deficiency of the employed bottom sampler which was prone to sample the surface layer of sandy bottom and the deeper layers of soft muddy bottom.

It is inferred that the want of nutriments was one of the major factors which precluded the occurrence of the biotype 1 organisms in deeper layers of sandy sea bottom.