Microscopic morphology of A. niger MYA 135 in submerged fermentation. Differential interference contrast images of cells developed in a basic medium at 25 (A), 30 (B) and 37°C (C) as well as those obtained in the presence of either 0.5 g |-1 CaCl2 (D) or 1 g |-1 FeCl3 (E). Restored cells observed at 37°C (F) or in the presence of 0.5 g |-1 CaCl2 (G) with the supplementation of 1.5 M NaCl. These images were taken after 72 h of cultivation. Extracellular compound (EC) produced during the early stages of pellets formation (H). All Panels are at the same magnification as A. Bar represents 10 μm. SV (Spherical Vacuole), TV (Tubular Vacuole), S (Septum), N (Nucleus), PS (Punctuate Structures).