Ultrasound enhanced phase partition of microorganisms

Aqueous two-phase partition is an established technique for the separation of many biological particles or solutes. Similarly, ultrasound is finding application in the harvesting of cell populations. We have combined the two methodologies to produce an elegant technique for separating and concentrating biological particles or solutes in an enclosed environment which is non-destructive and minimally perturbing to the objects being separated. Megahertz frequency ultrasonic standing wave fields produced either axially or radially from piezo-ceramic transducers dramatically reduce the time for completion of partition to about 1 min as demonstrated using Saccharomyces cerevisiae and Escherichia coli. The system described is competitive with established methods of cell separation and concentration.