EVIDENCE OF CYTOPLASMIC MEMBRANE INJURY IN THE DRYING OF BACTERIA

Abstract

Escherichia coli, which has undergone viability losses by freeze-drying, releases large amounts of UV-light-absorbing materials, including amino acids and ribonucleic acid fragments, in the presence of 0.1 ionic strength phosphate (pH 7.6). This leakage is accomapnied by a dissociation of the 25 and 40 S ribonucleoprotein particles in extracts derived from the dried cells. These effects are much less pronounced in media of lower ionic strength. The disintegration of ribonucleoprotein particles also occurs when extracts from undried E. coli are dialyzed in 0.1 ionic strength phosphate. Effects similar to those with freeze-dried E. coli were observed with Serratia macescens dispersed in aerosols. The release of UV-light-absorbing material and breakdown of ribonucleoprotein were also dependent on ionic concentration. These results may be interpreted in terms of an increased cell permeability following membrane damage as a primary effect of cell drying.