In vitro enrichment of trace elements promotes rapid germination of Aspergillus conidia: a clinical concern for immunosuppressed and hyperglycemic patients.

Abstract

Background and purpose: This study aimed to examine the effects of essential trace elements, namely iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu), combined with D-dextrose on conidial germination and growth of Aspergillus fumigatus and Aspergillus flavus ATCC strains. Trace elements are vital in metabolic processes, acting as cofactors for various enzymes; however, their precise role in fungal pathogenesis remains poorly understood.

Materials and methods: The research involved determining the minimum inhibitory concentrations (MIC) of Fe, Mn, Zn, and Cu for Aspergillus ATCC strains. Following MIC assessment, optimized concentrations of the trace elements (~140 and 550 pM) and various concentrations of D-dextrose (1-3% w/v) were introduced to assess their effects on fungal growth in RPMI 1640 broth. Growth was measured in terms of optical density, while conidial germination rates were also observed.

Results: The MICs for Fe, Mn, and Zn were found to exceed 35 µM, while Cu exhibited lower MICs of 2 and 7.6 µM against A. fumigatus and A. flavus, respectively. At optimized concentrations, Fe, Mn, Zn, and Cu significantly enhanced fungal growth in both Aspergillus species. Additionally, growth rates increased proportionally with higher D-dextrose concentrations. Notably, the combination of enriched trace elements and D-dextrose resulted in up to 98% conidial germination.

Conclusion: The findings demonstrate that optimized concentrations of essential trace elements and D-dextrose significantly promote conidial germination and growth of Aspergillus species in vitro. These results suggest that trace element supplementation might have important implications for immunocompromised and hyperglycemic patients. Further studies are warranted to explore the interactions between these micronutrients in fungal physiology and pathogenesis.