Novel Marine Archaebacteria: Potential Contribution to Midwater Biomass and Activity

这项研究调查了最近通过对海洋浮游细菌的分子遗传分析发现的新发现的古细菌群。这些生物的DNA序列是从100米和500米深的少营养开阔太平洋的一个地点采集的样本中恢复的。这一群占从500m获得的克隆的大部分(70%)，因此有迹象表明，它们可能在更深水域的生物量和新陈代谢中起着非常重要的作用。鉴于其他栖息地(极端嗜热菌、严格厌氧产甲烷菌、极端嗜盐菌等)中的大多数考古细菌通常占据的生态位具有“不同寻常”的性质，考古细菌的出现可能表明海洋广大内陆发生了意想不到的新陈代谢和生物地球化学过程。富尔曼博士将对更多的中水和深海样本进行核酸探针分析，以确定在海洋内部是否重复发现了这类细菌，如果是的话，估计这些生物相对于其他类型微生物的相对丰度。他将在检测呈阳性的样本中重复序列分析，以确定这些有机体是否与已发现的生物体难以区分。此外，他将尝试从淡水样本中进行非常困难的培养，以确定这些生物是否可以得到丰富，并可能从海水中分离出来进行实验室研究。他将与一名海洋有机地球化学家一起，分析古生菌特有类型的脂类。富集条件加上这些生物丰度的信息可能表明这些生物所介导的生物地球化学转化的重要性。虽然初步数据表明，这些生物可能是中水过程的主要贡献者，但有可能无法再次发现它们。

This research investigation looks at newly discovered groups of archaebacteria found recently by molecular genetic analysis of marine bacterioplankton. DNA sequences from these organisms were recovered from samples collected at one site in the oligotrophic open Pacific Ocean at depths of 100m and 500m. This group made up most (70%) of the clones obtained from 500m, so there is a suggestion that they may be very important in the biomass and metabolism of deeper waters. Given the "unusual" nature of the niches ordinarily occupied by most archaebacteria in other habitats (extreme thermophiles, strictly anaerobic methanogens, extreme halophiles, etc.), this occurrence of archaebacteria may suggest unexpected metabolic and biogeochemical processes in the ocean's vast interior. Dr. Fuhrman will perform nucleic acid probe analysis on additional midwater and deep sea samples to see if this group of bacteria is repeatably found in the interior ocean, and if so, to estimate the relative abundance of these organisms compared to other types of microbes. He will repeat the sequence analysis in samples that test positive, to determine if the organisms are indistinguishable from those already found. Additionally, he will attempt the very difficult culturing from fresh seawater samples to determine if these organisms can be enriched and possibly isolated from seawater for laboratory study. Along with a marine organic geochemist, he will analyse lipids for types unique to archaebacteria. The conditions of enrichment plus information on the abundance of these organisms may indicate the significance of biogeochemical transformations mediated by these organisms. While the preliminary data indicate these organisms may be major contributors to midwater processes, there is a risk of not finding them again.