LEXEN: Characteristics of Bacteria Native to Extremely Dilute Environments

贫营养环境包含的营养物质浓度范围从在真光水体中接近检测极限到在无光照的好氧水生系统中无法测量的稀释。这些环境的体积很大，含有足够的细菌，形成地球上生物量的主要组成部分。寡菌是目前主要的远洋生物，几乎是完全不可培养的，也许是因为它们的生长策略更倾向于营养收集，而不是诱导和调节细胞外溶质的过度运输。数量更多、可能更典型的寡菌的纯培养几乎总是不能繁殖。因此，寡菌的环境是极端的，因为不可能形成足够好的可靠生长的条件，这种情况源于所涉及的极小浓度。因此，从生物化学、分子生物学和动力学的角度来看，生长的一般策略还没有得到很好的理解。这项工作的目的是将更能代表少营养环境的细菌引入培养并报告其特性。为此，将从海水中制备灭绝培养物并确定培养能力。根据检测到的物种数量，可以确定母体水中可培养物种数量的估计。培养物在天然海水中不断混合和透析，以提供营养和去除废物。将根据流式细胞术模式从这些培养基中选择纯培养物，并研究其基本营养特性，以产生有用数量的生物量。所得到的培养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)注意渗透的细胞质和特别是膜蛋白分布，以及iv)详细的营养特性，包括指定营养摄取的动力学常数。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.