Freshwater Bacterial Aggregate Development: Effect of Dissolved Organic Matter

Abstract Suspended sediment particles and bacteria because of their surface area and charge, may play a role in the binding of aquatic contaminants. Little is known, as to what degree each of these factors play in the formation of suspended aggregates. Flocculation of particles can alter their hydrodynamic properties in aquatic environments and therefore may have significant implications for contaminant transport. In this study, we examine the role dissolved organic carbon plays in the production of bacterial aggregates as a first step to gaining a better understanding of bacterial-particle interactions and suspended particulate formation. Data indicated that an order of magnitude increase in bacterial population occurred due to the utilization of algal organic matter. This increase in bacterial density was closely accompanied by an increase in the size of the median bacterial aggregate from approximately 8 µm to 16 µm. This observation suggests that there is a greater potential for the sorption of aquatic contaminants by the aggregates.