Control of Cryptococcus neoformans in nature by biotic factors

Two bacterial species (Pseudomonas aeruginosa and Bacillus ubtilis) isolated from pigeon droppings, displayed anti Cryptococcus neoformans activity on 4 of 6 media nd sterilized pigeon droppings. Acanthamoeba palestinensis trophozoites isolated from pigeon droppings ingested and killed 99.9 % of C. neoformans cells after 7 days of incubation. Mites and sow bugs (Metoponorthus pruinosus) i olated from pigeon droppings appear to be fungivorous. These findings uggest that many organisms that occur in pigeon droppings influence C. neoformans persistence, reproduction, morphology and distribution i nature. Cryptococcus neoformans has been found worldwide, usually in soils containing pigeon droppings. Staib [16, 17] reported that pigeon droppings provide an excellent culture medium for Cryptococcus spp. In addition, he reported that fresh canary and pigeon excreta containing C. neoformans became free of the yeast after 6 days of incubation because of decomposition and alkalinization by bacteria. Walter & Yee [21] failed to isolate C. neoformans from chicken droppings. They suggested that this could be due to their high alkalinity and the presence of low molecular weight, thermostable, growth-suppressing substance(s) in this material. Littman & Borok [10