Biomechanical effects of shock waves on Escherichia coli and λphage DNA.

Escherichia coli (recombinant cells) and λphage DNA in suspension liquid were exposed to pressure pulses of about 20 μs duration and amplitude of up to 14 MPa. These pulses were generated by a diaphragmless shock tube. The destruction of cells was monitored by the assay of phenylalanine dehydrogenase leaking from the recombinant cells and was found to increase remarkably at the peak pressure of higher than 12 MPa. A probability relation for the cell destruction expressed as a function of pressure was proposed. It is most likely that there exists a threshold pressure for the cell destruction. Fragmentation effects of shock waves on λphage DNA were analyzed by electrophoresis. They were enhanced by increasing the shock wave strength and the number of shots. Probability for the DNA fragmentation as a function of pressure and molecular size was estimated with HPLC. The larger size of the DNA was more easily fragmented. A threshold pressure does not seem to exist for the DNA fragmentation. [ABSTRACT FROM AUTHOR]