LEXEN: Characteristics of Bacteria Native to Extremely Dilute Environments

9714298巴顿项目摘要：贫营养环境中的营养物质浓度从接近真光水域的检测极限，到有氧无光水系统中无法测量的稀释度不等。这些环境的体积很大，含有足够的细菌，足以构成地球上生物量的主要组成部分。寡杆菌是目前存在的主要远洋生物，几乎完全不可培养，可能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，以防止细胞外溶质的过度运输。数量更多、可能更典型的寡杆菌的纯培养几乎总是无法繁殖。因此，寡菌的环境是极端的，因为不可能形成足够好的条件来进行可靠的生长，而这种条件源于所涉及的极低浓度。因此，在生物化学、分子生物学和动力学方面的一般增长战略还没有得到很好的理解。这一努力的目的是使更能代表寡营养环境的细菌进入培养并报告它们的性质。为了做到这一点，将从海水中准备灭绝的文化，并建立培养能力。根据检测到的物种数量，可以确定母水中可培养物种的数量。培养物被连续混合，并与本地海水进行透析，以提供营养和清除废物。纯培养物将根据流式细胞仪的模式进行选择，并对基本营养特性进行调查，以生产有用数量的生物质。所得到的培养物将被用于更详细的研究，包括i)大小、DNA含量和细胞密度，ii)系统发育位置，iii)细胞质，特别是膜蛋白的分布，并注意渗透，以及iv)详细的营养特性，包括指定养分吸收的动力学常数。这些数据将被用来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.