The Survival of Escherichia coli sprayed into Air and into Nitrogen from Distilled Water and from Solutions of Protecting Agents, as a Function of Relative Humidity

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Abstract
The survival in air as a function of relative humidity (RH) and aerosol age is reported for E. coli (strains-B and Jepp) and for Serratia marcescens (strain-UK-8) sprayed for suspensions in distilled water and in solutions of dextran and of raffinose. The survival in nitrogen (>99.9%) of E. coli (strains-B, Jepp and commune) is given as a function of RH, when sprayed from suspension in distilled water and in raffinose solution. The results show that E. coli in the aerosol was subject to at least three stresses, an air stress, an RH stress, and a collection stress. The air stress accounted for loss of viability at low RH and the RH stress occurred at high RH and is expressed as RH ranges in which E. coli rapidly lost viability. The survival, expecially at high RH, depended upon the composition of the collecting fluid. At high RH a range of RH was found in which the bacteria were unstable when collected in phosphate buffer. Addition of raffinose (chosen as a typical protecting agent) to the spray fluid and the addition of M-sucrose to the collecting fluid eliminated the instability for E. coli (commune) and decreased it for the other two strains.