Controls of the microbial loop: Nutrient limitation and enzyme production, location and control.

A major controlling factor for bacterial growth is their ability to hydrolyze high molecular weight molecules too complex to be transported directly across the cell's membrane. The utility of such an extracellular enzyme hydrolysis system, location of the enzymes (free or attached), environmental controls of enzyme production, and implications of multiple hydrolysis-uptake systems are explored in relation to free-living oceanic bacteria and bacteria attached to rapidly sinking aggregates.