EVALUATION OF PHYSIOLOGICAL AND BIOCHEMICAL CHARACTERISTICS OF ALTERNARIA SPECIES ISOLATED FROM SOIL IN ASSIUT GOVERNORATE, EGYPT, IN ADDITION TO DICHOTOMOUS KEY TO THE ENCOUNTERED SPECIES

Mycobiota of 25 soil samples, collected from Botanical garden of Botany and Microbiology Department, Faculty of Science, Assiut University, were monitored on acidified weak potato dextrose agar (AWPDA), dichloran chloramphenicol peptone agar (DCPA), dichloran glycerol agar (DG-18) and potato carrot agar with manganese (PCA-Mn) media at 25 oC. One hundred and twenty-two species belong to 47 genera were obtained. Aspergillus was the most predominant genus on all media and A. niger was superior on AWPDA, DG18 and PCA-Mn. Fusarium was the runner up, followed by Alternaria, Curvularia, Talaromyces, Penicillium and Stachybotrys. Fifteen isolates of six species of Alternaria were subjected to some physiological and biochemical tests. The statistically analyzed results showed that, all isolates could significantly grow on ammonium tartarate, ammonium oxalate and glycine, while 14, 13 and 11 isolates wer able to grow on citric acid, lactic acid and sodium nitrite, respectively. Alternaria tenuissima and A. angustiovoidea were highly base producers from ammonium tartarate, while, the maximum base production on glycine was observed by A. angustiovoidea and A. arborescens. All isolates enabled to grow on creatine-sucrose and A. arborescens produced the strongest color, whereas the remaining isolates were negative (11 isolates) to moderate (3). On the other hand, A. chlamydospora and A. angustiovoidea showed maximum growth on mannitol and tannin-sucrose, respectively. Besides, the growth on 15 % NaCl-Cz was distinctive for 60 % and 50 % of A. alternata and A. angustiovoidea isolates, respectively.