Abstract: Objective To verify the role of pbs2 gene in the heat stress and cell wall stress of Aspergillus fumigatus.Methods The sensitivities of AF293 and pbs2 mutant growing on the YAG medium with different concentrations of Calcofluor white,Congo red and Sodium dodecyl sulfate (SDS) to the cell wall interfering compounds and to the echinocandins were observed.The expressions of pbs2 and hog1 gene of AF293 and the pbs2 mutant upon heat stress were detected by Real-time PCR.Results AF293 and the pbs2 mutant showed no difference in sensitivity to cell wall interfering compounds at 37℃,but the sensitivity of pbs2 mutant increased at 50℃.Calcofluor white (600 μg/mL),Congo red (400 μg/mL) or SDS (100 μg/mL) totally inhibited the growth of pbs2 mutant but had no effects on AF293.Compared to AF293,the pbs2 mutant showed increased sensitivity to echinocandins at 50℃,but no difference at 35℃ or 42℃.The MEC of caspofungin and micafungin to AF293 and the pbs2 mutant were 0.5 μg/mL at 35℃ and 42℃,0.25 μg/mL at 50℃,respectively.Echinocandins (0.5 μg/mL) could completely inhibited the growth of pbs2 mutant but not AF293 at 50℃.Upon heat stress at 50℃,the pbs2 and hog1 RNA expression of AF293 decreased to 3% and 13%,respectively,while the hog1 expression of the pbs2 mutant decreased to 35%.Conclusions The pbs2 gene plays a protective role in A.fumigatus adapting to the heat stress and cell wall stress.

Key words: Aspergillus fumigatus, pbs2, heat stress