The Aspergillus strains An-224 and An-270 showed in presence of zinc, a behavior which suggests that zinc was being used as a metabolic cofactor, similar case of Mortirella.
A change in the radial pattern of An-270, suggests a certain genetic mobility stimulated by the metal itself, in addition there is an increase of the diameter compared with the control strain in a dose-response relation. The strain growing pattern was not affected by lead but this metal induced a change in the radial pattern, we understand this as a genetic expression corresponding to the lining pattern in the surface which indicates certain changes in growing regulation genes and some other functions concomitant with the heavy metal resistance.
Both
tested strains (An-224 and An-270) were fully sensitive to mercury at the
doses applied. They also were resistant to copper at low concentrations
but not at high concentrations.
| This views show the response of Aspergillus strains to several heavy metal ions. At bottom and top, petri dish labeled (a) is An-224 control strain. Petri dishes labeled (b) and (c) show Aspergillus strains when grown in a media containing lead (Pb++) in 100 ppm and 500 ppm concentrations, in which the strain had a growing pattern similar to control strain changing only the spore pattern, An-270 strain had a similar pattern. Petri dishes labeled (d) and (e) show growth when zinc (Zn++) was added in 100 ppm and 500 ppm concentrations which show similar behavior like lead (Pb++). At bottom we observe the same experiment but using copper (Cu++), in this case, strains exposed to 100 ppm of copper (f) developed a growing diameter similar or bigger than control (g), using 500 ppm of copper the colonies were inhibited partially. A very interesting observation is the lining pattern over the colonies (white) surface which indicates a very strong genetic mobility in function to the heavy metal concentration. | |
This
Aspergillus strains were, as most of the fungus tested, sensitive to mercury.