TOXINS OF PSEUDOMONAS PSEUDOMALLEI II

Abstract

Two thermolabile exotoxins were demonstrated in crude filtrates of P. pseudomallei by selective adsorption to Duolite S-30 resin and elution with pH 10 buffer. One toxin was lethal and necrotizing, whereas the other toxin was lethal but nonnecrotizing. Both toxins were partially inactivated by heating at 60[degree]C for 30 minutes and were completely inactivated by boiling for 10 minutes. Neither toxin was inactivated by acetone or alcohol but both were detoxified by phenol or formaldehyde. The lethal toxin was most stable between pH 6 and 9. Both toxins were precipitated by 35% amonium sulfate, but not by 20%. Both were retained by dialysis membranes but were not sedimented by centrifugation at 105, 400 X G. Neither had any appreciable electrical charge between pH 6.5 and 9.3 as determined by electrophoretic separation and by sampling at various levels in the Tiselius cell. Both exotoxins are probably low molecular weight proteins having few ionizable radicals. The toxoid was immunogenic as shown by the fact that repeated inoculation of mice gave protection against 15 to 18 LD50 of ammonium sulfate precipitated toxin.