Adventitious chemistry at reduced water activities: free radicals and polyhydroxy agents.

Free radicals have been associated with loss of viability of lyophilized bacteria exposed to oxygen. Free radical concentration was proportional to the log of the oxygen pressure in the sample. Sugars, such as lactose or sucrose, preserved viability and inhibited free radical production.

Infection of mice by aerosols of Klebsiella pneumoniae under hyperbaric conditions.

Both the physical behavior of aerosols and survival of airborne Serratia marcescens in hyperbaric chambers with a helium-air mixture at 20 atm of pressure was approximately the same as in the system at ambient pressures. Exposure of mice to aerosols of Klebsiella pneumoniae at 1-, 2-, and 17-atm (ca. 101-, 203-, and 1,722-kPa) pressures of helium-oxygen mixture showed that the number of viable organisms constituting a 50% lethal dose was not significantly affected by the hyperbaric conditions.

Virulence and viability of Yersinia pestis 25 years after lyophilization.

When equal volumes of 6% lactose and a broth culture of Yersinia pestis were mixed before freezing, approximately 50% of the cells survived lyophilization and reconstitution on the following day. Concomitantly, the number of viable cells per 50% lethal dose increased from about 16 to 125 organisms. On subsequent storage of the lyophilized cells under vacuum in glass ampoules at 4 degrees C for 25 years, more than 25% of the cells remained viable.

Rhythmic changes in dry heat resistance of Bacillus subtilis spores after rapid changes in pH.

Heat resistance of freeze-dried Bacillus subtilis spores varied in a rhythmic manner as a function of time between acidification to about pH 1.5 and freezing. A comparable rapid shift to pH 11 produced little change in resistance to heat.

Metabolic disposition of 2,4,6-trinitrotoluene.

Three pseudomonas-like organisms have been shown to metabolically oxidize 2, 4, 6-trinitrotoluene (TNT). Capability for this oxidative dissimilation varied with each organism. Of the three, isolate "Y" was the most proficient, isolate "I" was less, and isolate "II" was the least.

Vibrio enterotoxin in miniature pigs.

Miniature pigs appear to be less sensitive than rabbits to cholera toxin introduced into segments of the ileum.

Possible mechanisms of action of an anti-Pasteurella pestis factor.

Anti-Pasteurella pestis factor (APF) inhibited bacterial growth, but there was no evidence that APF from either mouse or guinea pig or selected fatty acids physically disrupted the cell wall. The fatty acids selected were representative of those found in APF. APF inhibited oxidation of beta-d-glucose but not oxidation of glucose-6-phosphate, whereas fatty acids inhibited the oxidation of glucose-6-phosphate but not oxidation of beta-d-glucose.

Correlations between free radical production and viability of lyophilized bacteria.

When Serratia marcescens cultures were treated with dilute solutions of phenol or hydrogen peroxide before drying or by lyophilization at suboptimal pH, the log of the number of cells surviving lyophilization was correlated with subsequent free radical production by the dried cells. Since the rate of free radical production and rate of death were similarly affected by temperature, the log of the number of cells surviving after 6 days was inversely related to the free radical concentration at that time. Free radicals were produced in proportion to the log of oxygen pressure, and viability was inversely related to oxygen tension; again, free radical concentration appeared to be correlated with the death of organisms.

Studies on survival of bacteria: rhythmic response of microorganisms to freeze-drying additives.

Various materials were mixed with suspensions of Serratia marcescens and other organisms. Samples were removed and frozen at intervals after mixing; the number of cells that survived both freeze-drying and exposure to air varied rhythmically as a function of time between mixing and freezing. When assayed before or immediately after drying there were essentially no fluctuations.

DIFFERENTIATION OF EXOTOXIN AND OTHER BIOLOGICALLY ACTIVE SUBSTANCES IN PSEUDOMONAS PSEUDOMALLEI FILTRATES.

Heckly, Robert J. (University of California, Berkeley). Differentiation of exotoxin and other biologically active substances in Pseudomonas pseudomallei filtrates.

FREE RADICAL FORMATION AND SURVIVAL OF LYOPHILIZED MICROORGANISMS.

Heckly, Robert J. (University of California, Berkeley), R. L.

On the size of the toxic particle passing the intestinal barrier in botulism.

On the basis of toxicity assays using partition centrifugation cells it was established that the sedimentation coefficient of type A botulinum toxin appearing in the lymph of orally poisoned rats was 7.9 x 10(-18) cm. per dyne sec.