Morphological responses of two Aspergillus oryzae strains to various metal ions at different concentrations

Aspergillus species take up various metal ions from environment. The morphology of Aspergillus oryzae strains can vary under the influence of various metal ions. Here, the effects of Ti⁴⁺, V³⁺, Sr²⁺, Ba²⁺, Al³⁺, Fe²⁺, Zn²⁺, Mn²⁺, Ca²⁺, and Cu²⁺ on morphological parameters of A. oryzae strains RIB40 and RIB143 were estimated. Colony diameter, conidiation, vesicle head size, and stipe width in both strains varied with concentration. Ti⁴⁺, Sr²⁺, Ba²⁺, Al³⁺, Fe²⁺, and Ca²⁺ affected conidiation in similar tendency between two strains. The effects of Ti⁴⁺, V³⁺, Sr²⁺, and Ba²⁺ on the morphology of A. oryzae are reported here for the first time. Induction of growth of both strains by 0.0001% Ti⁴⁺ may help the fermentation industry. Induction of conidiation in RIB40 by 0.001% Cu²⁺ confirmed previous results that low concentrations of Cu²⁺ promote the growth of Aspergillus. The most novel finding is that 0.001% Zn²⁺ increased the vesicle head size in RIB40; possible reasons are discussed.