Preservation of dissoloved organic matter in the Ocean

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1. Recent studies have demonstrated that organic polymers derived from bacteria accumulate in seawater, yet the dynamics of this large pool of dissolved organic matter has been poorly understood. This study examined the turnover and transformation of peptidoglycan-a major constituent of dissolved organic nitrogen in oceanic waters.2. A new methodology was developed to isolate and purify paptidoglycan from marine bacteria.3. It was succeeded in preparing radio-labeled peptidoglycan. By using this material, a new assay technique was developed to examine turnover and transformation of peptidoglycan in natural seawater.4. The measurements of peptidoglycan degradation in a wide variety of marine environments demonstrated the uncoupling of hydrolysis and uptake of peptidoglycan.5. Ectoenzyme activities (peptidase and glucosidase) were determined in the subarctic Pacific. Results revealed a dramatic shift in the vertical profile of activity ratios along the east-west axis of the investigated region.6. Bacterial biomass and activity were determined in meso-and bathypalagic environments. Our results suggested that sinking particles are actively solubilized to release dissolved and colloidal polymers in deep oceanic environments.7. A descriptive model was developed to explain the release and accumulation of organic polymers derived from bacteria.