Substances which Protect Lyophilized Escherichia coli against the Lethal Effect of Oxygen

Abstract

The lethal effect of oxygen on Escherichia coli organisms freeze-dried from water may be partly abolished by the addition of certain compounds before lyophilization. Three groups of such protective compounds were found: (i) thiourea, some of its derivatives and analogues; (ii) sugars, especially monosaccharides and some of their derivatives; (iii) some simple inorganic salts. The protective action was not unequivocally correlated with reducing power. Certain reducing agents (e. g. sodium dithionite, cysteine, reduced glutathione) even enhanced the lethal effects of oxygen.