Colquhoun J A, Heald S C, Li L, Tamaoka J, Kato C, Horikoshi K, Bull A T
Department of Biosciences, University of Kent, Canterbury, UK.
Extremophiles. 1998 Aug;2(3):269-77. doi: 10.1007/s007920050069.
Deep-sea soft sediments from trench systems and depths in the northwestern Pacific Ocean ranging from less than 300 to 10,897 m in depth have been analyzed for three target genera of actinomycetes: Micromonospora, Rhodococcus, and Streptomyces. Only culturable strains, recovered at atmospheric pressure on selective isolation media, have been examined to date. Maximum recoveries of culturable bacteria were greater that 10(7)/ml wet g sediment, but actinomycetes comprised a small proportion of this population (usually less than 1%). The target actinomycetes were isolated at all depths except from the Mariana Trench sediments. Actinomycete colonies were defined initially on the basis of colony morphologies, and preliminary identification then was made by chemotaxonomic tests. Pyrolysis mass spectrometry (PyMS) of deep-sea mycolic acid-containing actinomycetes gave excellent correspondence with numerical (phenetic) taxonomic analyses and subsequently was adopted as a rapid procedure for assessing taxonomic diversity. PyMS analysis enabled several clusters of deep-sea rhodococci to be distinguished that are quite distinct from all type strains. 16S rRNA gene sequence analysis has revealed that several of these marine rhodococci have sequences that are very similar to certain terrestrial species of Rhodococcus and to Dietzia. There is evidence for the intrusion of terrestrial runoff into these deep trench systems, and the inconsistency of the phenotypic and molecular taxonomies may reflect recent speciatiion events in actinomycetes under the high-pressure conditions of the deep sea. The results of DNA-DNA pairing experiments point to the novelty of Rhodococcus strains recovered from hadal depths in the Izu Bonin Trench. Biotransformation studies of deep-sea bacteria have focused on nitrile compounds. Nitrile-metabolizing bacteria, closely related to rhodococci, have been isolated that grow well at low temperature, high salt concentrations, and high pressures, suggesting that they are of marine origin or have adapted to the deep-sea environment.
对西北太平洋海沟系统深度范围从不到300米至10897米的深海软沉积物进行了分析，以研究放线菌的三个目标属：小单孢菌属、红球菌属和链霉菌属。迄今为止，仅对在大气压下于选择性分离培养基上获得的可培养菌株进行了检测。可培养细菌的最大回收率大于10(7)/毫升湿克沉积物，但放线菌在该菌群中所占比例较小（通常小于1%）。除马里亚纳海沟沉积物外，在所有深度均分离到了目标放线菌。放线菌菌落最初根据菌落形态进行定义，然后通过化学分类测试进行初步鉴定。对含分枝菌酸的深海放线菌进行的热解质谱分析（PyMS）与数值（表型）分类分析结果高度吻合，随后被用作评估分类多样性的快速方法。PyMS分析能够区分出几类深海红球菌，它们与所有模式菌株都截然不同。16S rRNA基因序列分析表明，其中一些海洋红球菌的序列与红球菌属的某些陆地物种以及迪茨氏菌属的序列非常相似。有证据表明陆地径流侵入了这些深海海沟系统，表型和分子分类法的不一致可能反映了深海高压条件下放线菌最近的物种形成事件。DNA-DNA配对实验结果表明，从伊豆小笠原海沟超深渊深度分离出的红球菌菌株具有新颖性。对深海细菌的生物转化研究主要集中在腈类化合物上。已分离出与红球菌密切相关的腈代谢细菌，它们在低温、高盐浓度和高压条件下生长良好，这表明它们起源于海洋或已适应深海环境。
