LEXEN: Characteristics of Bacteria Native to Extremely Dilute Environments

9714298按钮 项目摘要 寡营养环境中的营养物浓度范围从接近透光沃茨的检测极限到有氧无光水生系统中的不可测量稀释。这些环境体积大，含有足够的细菌，形成地球上生物量的主要组成部分。寡细菌，占主导地位的浮游生物，几乎完全不可培养，也许是因为他们的生长策略有利于营养收集诱导和调节过度运输的细胞外溶质。数量更多且可能更典型的寡细菌的纯培养物几乎总是不能繁殖。因此，寡细菌的环境是极端的，因为条件已经不可能制定足够好的可靠的增长，一个条件源于极小的浓度。因此，生物化学、分子生物学和动力学方面的一般生长策略还没有得到很好的理解。 这项工作的目的是使细菌更能代表贫营养环境的培养，并报告其特性。为了做到这一点，灭绝文化将准备从海水和可培养性建立。根据检测到的物种数量，可以确定母体水中可培养物种的估计数量。培养物不断混合，并对天然海水进行透析，以提供营养和去除废物。将基于流式细胞术模式从这些中选择纯培养物，并研究其基本营养特性，以产生有用量的生物质。所得培养物将用于更详细的研究，包括i）大小、DNA含量和细胞密度，ii）系统发育位置，iii）细胞质和特别是膜蛋白分布（注意渗透酶），以及iv）详细的营养特性，包括指定营养吸收的动力学常数。这些数据将用于推进寡营养功能的概念。

9714298 Button PROJECT SUMMARY Oligotrophic environments contain nutrient concentrations that range from near the limits of detection in euphotic waters to unmeasurably dilute in aerobic unlighted aquatic systems. Large in volume, these environments contain sufficient bacteria to form a major component of biomass on earth. Oligobacteria, the dominant pelagic organisms present, are almost totally unculturable, perhaps because their growth strategies favor nutrient collection over induction and regulation against excessive transport of extracellular solutes. Pure cultures of the more numerous and probably more typical oligobacteria virtually always fail to propagate. Thus the environment of oligobacteria is extreme because conditions have been impossible to formulate sufficiently well for dependable growth, a condition stemming from the extremely small concentrations involved. General strategies for growth in terms of biochemistry, molecular biology and kinetics are therefore not well understood. The aim of this effort is to bring bacteria more representative of the oligotrophic environment into cultivation and report their properties. To do this, extinction cultures will be prepared from seawater and culturabilities established. From the number of species detected, estimates of the number of culturable species in the parent water can be determined. Cultures are continuously mixed and dialyzed against native seawater for nutrient supply and waste-product removal. Pure cultures will be selected from these on the basis of flow cytometry patterns and investigated for basic nutritional properties in order to produce useful quantities of biomass. The resulting cultures will be used for more detailed investigations to include i) size, DNA content, and cell density, ii) phylogenetic location, iii) cytoplasmic and particularly membrane protein distributions with attention to permeases, and iv) detailed nutri tional properties including the kinetic constants that specify nutrient uptake. These data will be used to advance concepts of oligotroph functionality.