Exogenous factors affecting growth of Aspergillus species.

Aflatoxins are the most deleterious fungal metabolites in humans, animals and plants. Recently, more attention has been paid to the occurrence and growth of Aspergillus spp. In this study, the effects of pH, light, relative humidity (RH) and temperature on the growth of Aspergillus spp. were investigated using broth medium. Results revealed highest mean of dried mycelial weight (365.67mg) at pH 4.0. The highest spores per ml (8.243 × 107) at pH 5.0. Similarly, growth during darkness was higher on first day of incubation in A. candidus and A. niger, while A. flavus and A. fumigatus showed the highest growth under continuous light. Lower RH% (32.5%) favored only the growth of A. niger. However, the growth in other Aspergillus species was significantly increased by RH% (50.5%, 85.0% and 100%). At 40C, only A. fumigatus and A. flavus showed significant (P<0.05) growth. There were significant differences in all the treatments (P<0.05). This proposes that these interacting environmental conditions impact significant effect on Aspergillus growth. [ABSTRACT FROM AUTHOR]