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.
