Inactivation kinetics of some microorganisms subjected to a variety of stresses

Loss of viability in aerosols of Escherichia coli B, E. coli commune, E. coli Jepp (in nitrogen atmospheres), and Semliki forest virus (in air) was determined as a function of relative humidity at 26.5 C. The decay patterns could be accounted for accurately by means of an equation derived from a postulated mechanism involving population distributions and first-order denaturation kinetics. Analyses of published curves describing loss of viability (all of which were semiexponential, ie., J-shaped) for various microorganisms stressed by different techniques showed that the proposed mechanism also provided an explanation for effects of the following factors (in the absence of open air, oxygen, or radiation): (i) influence of relative humidity upon aerosol susvival; (ii) dissemination of aerosols from the wet and dry states; (iii) protecting additives; (iv) relative humidity change before reconstitution; (v) reconstituting fluids; (vi) water content of freeze-dried product; (vii) storage gas; and (viii) storage temperature. The date indicate that low temperatures and high pressures were likely to be conducive to the preservation of viable bacteria and viruses, provided that cold shock and decompression shock were absent.