Pseudomonas aeruginosainhibitsRhizopus microsporusgermination through sequestration of free environmental iron

Abstract

AbstractRhizopus sppare the most common etiological agents of mucormycosis, causing over 90% mortality in disseminated infection. Key to pathogenesis is the ability of fungal spores to swell, germinate, and penetrate surrounding tissues. Antibiotic treatment in at-risk patients increases the probability of the patient developing mucormycosis, suggesting that bacteria have the potential to control the growth of the fungus. However, research into polymicrobial relationships involvingRhizopus spphas not been extensively explored. Here we show that co-culturingRhizopus microsporusandPseudomonas aeruginosaresults in the inhibition of spore germination. This inhibition was mediated via the secretion of bacterial siderophores, confirming the essential role of iron for fungal growth. Addition ofP. aeruginosasiderophores toR. microsporusspores in the zebrafish larval model of infection resulted in inhibition of fungal germination and reduced host mortality. Therefore, during infection antibacterial treatment may relieve bacterial imposed nutrient restriction resulting in secondary fungal infections.