CHARACTERIZATION OF BAROPHILIC DEEP-SEA MICROORGANISMS

为了描述深海嗜水微生物的特征，研究从两种方式进行，一种是在东京大学海洋研究所的研究船上进行的，另一种是在实验室中用从深海分离的细菌菌株进行的。在白虎丸号的巡航中，在压力下从日本海沟中分离出了几株嗜盐深海细菌。利用高压-温度梯度仪（PTG）研究了这些菌株的生长特性。菌株JT403在20MPa和5.1C条件下生长最佳，为0.047 h^<-1>。另一株专性嗜氧细菌JT 761在600MPa和1.8℃条件下的生长速度为0.054h-1，表现出最佳的生长速度，对从太平洋地表水到深海分离的60株海洋弧菌进行了16S rRNA基因的PCR/RFLP分析。聚类依赖于菌株所分离的生态位，且来自日本深海和沿海地区的菌株在基因型组成上存在显著差异。一个大的系统发育系是与海洋弧菌非常接近的嗜冷或嗜冷的深海弧菌。另一种系为分布于日本沿海地区的类群。

To characterize barophilic deep-sea microorganisms, studies were conducted from two ways, namely, one during a cruise on board the research vessel, Hakuho-maru or Tansei-maru, Ocean Research Institute, University of Tokyo, and another one in the laboratory with isolated strains of bacteria from deep-sea. During the cruise by Hakuho-maru, several strains of barophilic deep-sea bacteria were isolated from the Japan Trench under pressure. The growth characteristics of these strains were investigated using High-Pressure-Temperature-Gradient Instrument (PTG apparatus). One strain JT403, isolated from 4000m, showed optimum growth, 0.047 h^<-1>, at 20MPa and 5.1C.Another obligate barophilic bacterial strain JT 761, showed optimum growth, 0.054h-1, at 600MPa and 1.8 C.Grouping of 60 marine Vibrio strains isolated from surface water to deep-sea in the Pacific Ocean using PCR/RFLP analysis of 16S rRNA genes were conducted. The clusters were depended on the isolated n niche of the strains and showed significant differences in the genotype composition between the strains from the deep-sea and the coastal area of Japan. One large phylogenetic line was psychrophilic or psychrotrophic deep-sea vibrios very close to Vibrio marinus. Another line was V.splendidus-like group distributed in the coastal area of Japan.