Inactivation of Aspergillus Spores in Clinical Wastes by Supercritical Carbon Dioxide

The present work investigated the inactivation of Aspergillus spp. spores by supercritical carbon dioxide (SC-CO2) based on the destruction of enzyme activity and the alteration of spore morphology as documented using a scanning electron microscope (SEM). Six Aspergillus spp. included A. niger, Aspergillus sp. in section Nigri, A. fumigatus, A. tubingensis, A. hortai and Aspergillus sp. strain no 145 were isolated from clinical waste samples and inactivated by using SC-CO2 at optimal conditions (35 MPa, 75°C and 90 min). The inactivation of spores was determined by the culturing method. Aspergillus sp. strain no 145 and Aspergillus hortai were further analysed to quantify enzyme activity, and the morphology of spores was determined by SEM to demonstrate the inactivation mechanism. The results revealed that growth and enzyme activity of the SC-CO2 treated fungal spores were not detected. The SEM observation demonstrated complete destruction of spore morphology and exsorption of protoplasmic contents. The findings proved the high efficiency of SC-CO2 for the destruction of fungal contaminants in clinical wastes.