Turbulent-flow drag reduction by polymers from marine and fresh water bacteria

Bacteria which produce drag-reducing polymers have been isolated from eleven hydrodynamic test facilities in the United States, Great Britain, and France, and appear to be ubiquitous in all fresh and ocean water. These polymers are likely extracellular polysaccharides and have been produced by bacteria which grow at either cold, moderate, or high temperatures. Sugar enrichment studies suggest that the absence of suitable energy and carbon sources limit polymer production in natural waters. In order to maintain constant drag in hydrodynamic test facilities, it is recommended that primary production by algae be prevented and degradable organic material be eliminated in order to minimize potential carbon sources for bacterial drag-reducing polymer synthesis. Some drag-reducing polymers from bacteria may be concentrated by bubbling, and implications of this phenomenon are discussed.