Aspergillus fumigatus tolerance to high temperature is considered to be a possible virulence factor. We have monitored its growth potential after culture at 27'C, 37'C, 41'C and compared it with that of other less virulent Aspergillus species : A. flavus and A. terreus. Organisms grown in Czapeck medium supplemented with yeast extract 0.1%. The time of incubation depending on the temperature and the species (from 7h30 to 16h). Germ tubes were separated from liquid medium by filtration through membrane. Surface proteins and glycoproteins were extracted by sequential treatment with mercapto 2 ethanol and lithium chloride. The extracts and their corresponding filtrates were dialysed, concentrated and analysed by isoelectrofocusing (IEF) and SDS-PAGE. A. fumigatus grew well under stressful conditions, A. flavus less well, while the thermotolerance of A. terreus was poor. Silver staining of IEF and SDS-PAGE gels showed complex protein patterns for all these three species. The proportion of high molecular weights components increased as a function of increasing growth temperature in A.fumigatus germ tube extracts. These components were glycoproteins which bound selectivly to Concanavalin A and wheat germ agglutinin, indicating the presence of mannose and/or glucose residues and N acetyl glucosamine oligomers. Essentially quantitative differences were seen with the correspondent culture filtrates. The response to prolonged high temperature was different in these three species. At present, we could not say if it is only related to an increase of metabolic activity or if it corresponds to new synthesis for some components in function of temperature adaptability.
Full conference title:
The 2nd Meeting of the European Confederation of Medical Mycology
- ECMM 2nd (1995)