The IPI1 Family Protein-Encoding Gene ipi1 in Aspergillus fumigatus Influences Growth, Sporulation, Stress Responses, and Mortality of Infected Galleria mellonella Larvae

Aspergillus fumigatus is an opportunistic pathogen threatening human health, but the function of its ipi1 gene remains unclear. An ipi1 deletion strain (Δipi1), a complemented strain (Δipi1::ipi1+), and an overexpression strain (ipi1-OE) were constructed by homologous recombination. The phenotypic characteristics, stress responses, antioxidant enzyme activities, reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP), and transcriptomic profiles were analyzed. Larval mortality was recorded in the Galleria mellonella infection model and analyzed by survival analysis. Compared with the wild-type strain (WT), both the Δipi1 and ipi1-OE strains exhibited slower growth and altered responses to oxidative and osmotic stress. The Δipi1 strain exhibited increased sporulation density and abnormal hyphal morphology, and was associated with more rapid larval mortality. The ipi1-OE strain exhibited transiently increased sporulation density and fewer conidial heads and was associated with lower larval mortality. Both mutants exhibited decreased T-SOD and CAT activities, elevated ROS levels, reduced MMP, and altered transcript levels of genes involved in transmembrane transport and metabolism. Conclusions: ipi1 plays an important role in growth, stress responses, antioxidant defense, mitochondrial function, and sporulation in A. fumigatus, and its deletion or overexpression is associated with altered larval mortality in the G. mellonella infection model.