Extracellular phospholipase, protease and hemolysin production by strains of opportunistic yeasts from the excreta of Mew Gulls breeding in natural and urban habitats.

Extracellular hydrolytic activity (phospholipase, protease and hemolysin production) was evaluated in 178 strains of potentially pathogenic ascomycetous (Candida parapsilosis, Candida tropicalis) and basidiomycetous (Rhodotorula mucilaginosa) yeasts isolated from the excreta of Mew Gulls. Two bird colonies, one nesting in a natural habitat and the other in an urban habitat at the landfill, were studied simultaneously during their 7-month breeding season. Significant differences in phospholipase and protease production were found between natural and anthropophized strains. Both virulent activities were higher in strains of potentially pathogenic yeast species isolated from the excreta of Mew Gulls nesting in the anthropogenic habitat near the landfill. No significant differences were found in hemolysin production. Thus, synanthropic migratory birds nesting in an urban area could be involved in the wide spread of yeast virulence. It seems very important to advocate that landfills in urban areas are nowadays closed and "relocated" to large distances from cities and that biowaste is treated before dumping in order to prevent and minimize its negative impact on the environment (water, soil, air) and human health.