Nitrogen utilisation and growth at reduced water activity by mucoralean fungi present in soil

Nine mucoraiean fungai genera including 18 species were examined for their ability to utilise a series of nitrogen containing compounds and to grow at an aw of 0.955 on solid media The nitrogen concentration in the media was 0.1 g/1 and the series of nitrogen containing compounds were ammonium chloride, asparagine, sodium glutamate, sodium nitrite and potassium nitrate. The genera were Actinomucor Schostak. Backusella Hesselt, & J.J. Ellis, Cunningharnella Matr., Gongronella Ribaldi, Mortierella Coem. Mucor Fresen, Rhizomucor Lucet & Costantin, Rhizopus Ehrenb and Thamnostylum Arx & H, P. Upadhyay, Thirty-nine fungal strains obtained from culture collections (CBS, MUFS and PPRI), as well as 12 soil isolates from the Karoo, were tested. All the species and strains tested in this study were able to utilise asparagine and glutamate. Strains belonging to Cunningharnella, Mucor racemosus Fresen., Rhizopus microsporus Tiegh. and Rhizopus stolonifer (Ehrenb.: Fr) Vuill were unable to utilise ammonium chloride. Strains of Cunningharnella, Mortierella, Rhizomucor, Rhizopus microsporus and Rhizopus stoionifer were unable to grow on nitrate as sole nitrogen source. Nitrite was found to be toxic to species belonging to Cunningharnella, Mortierella, Rhizomucor, Rhizopus and Thamnostylum. Members of Gongronella, Mortierella, Mucor racemosus, Rhizomucor and Thamnostylum were unable to grow at an aw of 0.955