Studies on Aspergillus fumigatus; stability of haemolysin and toxin in crude filtrate.

The haemolysin and toxin in mycelial filtrates of Aspergillus fumigatus showed a distinct difference in stability when the filtrate was heated at 60°C and pH 6.7, as well as at 40 °C and pH 9.5, the toxin being more stable. When the filtrate was heated at 40 °C and pH 2.5, a rapid inactivation of both haemolysin and toxin occurred. No haemolytic or toxic activity could be demonstrated in a filtrate with a 6 × 10M concentration of formalin after incubation at 37 °C for 3 and 4 days, respectively. Serum prepared with formalin-treated filtrate as antigen had a haemolysin- and toxin-neutralizing effect. When mercury chloride or p-chloromercuribenzoate in a final concentration of 10M was added to the filtrate, immediate blocking of the haemolytic activity, but not of the toxic, was obtained. Haemolysin inactivated by mercury in a final concentration of 10M was reactivated under the influence of L-cysteine or glutathione in a final concentration of 10M.