Significance of Bacterial Hydrolases in Particle Degradationand Carbon Flow Pathways in the Ocean's Mesopelagic Zone

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It is important to understand how particles which are formed in the upper layers of the ocean are transformed as they sink out of those upper layers into the benthos. Bacteria play a major role in the transformation of the particles on their way to the bottom. Much of the organic matter associated with these particles is converted to the dissolved state, a form in which it can be utilized by phytoplankton and other bacteria for growth. Dr. Azam's previous results have led to the hypothesis that the attached bacteria, via secretion of certain enzymes (hydrolases) into the particle, are responsible for large scale solubilization and fragmentation of the particles. The result is that most of the dissolved organic material diffuses out of the particle and is utilized by free-living bacteria. In the present study, the magnitude and mechanisms of this pathway are explored. The research focuses on the regulation of several enzymes that control the transformation from the particulate to the dissolved state. The study contributes toward the understanding of the role of bacteria in biogeochemical cycling pathways of organic matter.