| Abstract: | Summary The results of this study indicate thatHistoplasma capsulatum in its saprophytic form is able to utilize the major nitrogenous constituent of avian manure as a nitrogen source. In addition, the enzymes responsible for the pathway of uric acid degradation to inorganic nitrogen have been demonstrated in cell-free systems. These enzymes include uricase, allantoinase, allantoicase, and urease. The uricase ofHistoplasma appears to be a cell wall or cell membrane-associated enzyme, while the other enzymes were located in the soluble portion of cell-free extracts. Cell-free extracts ofCryptococcus neoformans are actively uricolytic.It is suggested that this ability ofH. capsulatum hyphae to utilize uric acid and related compounds as growth substrates may in part explain the indisputable ecologic association of this pathogenic fungus with avian and possibly chiropteran-associated soils and habitats in those areas endemic for histoplasmosis.From the Research Laboratories, Veterans Administration Hospital, Kansas City, Missouri, the Department of Biology, University of Missouri at Kansas City and the Department of Microbiology, University of Kansas School of Medicine, Kansas City, Kansas. Supported by VA-8200 funds.Portion of a Thesis presented by the senior author to the Graduate Faculty of the University of Missouri at Kansas City as partial fulfillment of the requirements for the Degree of Master of Arts. |
