Open AccessPhysiological Responses of Aspergillus niger Challenged with Itraconazole
Author(s) -
Jan Struckmann Poulsen,
Anne Mette Madsen,
John Kerr White,
Jeppe Lund Nielsen
Publication year - 2021
Publication title -
antimicrobial agents and chemotherapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.07
H-Index - 259
eISSN - 1070-6283
pISSN - 0066-4804
DOI - 10.1128/aac.02549-20
Subject(s) - aspergillus niger , itraconazole , pathogen , fungal pathogen , antifungal , biology , microbiology and biotechnology , fungi imperfecti , aspergillus , opportunistic pathogen , bacteria , pseudomonas aeruginosa , genetics
Aspergillus niger is an opportunistic pathogen commonly found in a variety of indoor and outdoor environments. An environmental isolate of A. niger from a pig farm was resistant to itraconazole, and in-depth investigations were conducted to better understand cellular responses that occur during growth when this pathogen is exposed to an antifungal. Using a combination of cultivation techniques, antibiotic stress testing, and label-free proteomics, this study investigated the physiological and metabolic responses of A. niger to sublethal levels of antifungal stress. Challenging A. niger with itraconazole inhibited growth, and the MIC was estimated to be > 16 mg · liter -1 Through the proteome analysis, 1,305 unique proteins were identified. During growth with 2 and 8 mg · liter -1 itraconazole, a total of 91 and 50 proteins, respectively, were significantly differentially expressed. When challenged with itraconazole, A. niger exhibited decreased expression of peroxidative enzymes, increased expression of an ATP-binding cassette (ABC) transporter most likely involved as an azole efflux pump, and inhibited ergosterol synthesis; however, several ergosterol biosynthesis proteins increased in abundance. Furthermore, reduced expression of proteins involved in the production of ATP and reducing power from both the tricarboxylic acid (TCA) and glyoxylate cycles was observed. The mode of action of triazoles in A. niger therefore appears more complex than previously anticipated, and these observations may help highlight future targets for antifungal treatment.