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O'Meara TR. Going fishing: how to get what you want from a fungal genetic screen. mSphere 2024:e0063823. [PMID: 38958459 DOI: 10.1128/msphere.00638-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024] Open
Abstract
Five years ago, as I was starting my lab, I wrote about two functional genomic screens in fungi that had inspired me (mSphere 4:e00299-19, https://doi.org/10.1128/mSphere.00299-19). Now, I want to discuss some of the principles and questions that I ask myself and my students as we embark on our own screens. A good screen, whether it is a genetic or chemical screen, can be the starting point for new discovery and an excellent basis for the beginning of a scientific research project. However, screens are often criticized for being "fishing expeditions." To stretch this metaphor to the extreme, this is because people are worried that we do not know how to fish, that we will come home without any fish, bring home the wrong fish, or not know what to do with a fish if we caught it. How you set up the screen and analyze the results determines whether the screen will be useful. In this mini-review, and in the spirit of teaching a scientist to fish, I will discuss recent excellent fungal genetic and chemical screens that illustrate some of the key aspects of a successful screen.
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Affiliation(s)
- Teresa R O'Meara
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
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2
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Kelty MT, Miron-Ocampo A, Beattie SR. A series of pyrimidine-based antifungals with anti-mold activity disrupt ER function in Aspergillus fumigatus. Microbiol Spectr 2024:e0104524. [PMID: 38916314 DOI: 10.1128/spectrum.01045-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 05/23/2024] [Indexed: 06/26/2024] Open
Abstract
Fungal infections are a major contributor to morbidity and mortality among immunocompromised populations. Moreover, fungal disease caused by molds are difficult to treat and are associated with particularly high mortality. To address the need for new mold-active antifungal drugs, we performed a high-throughput screen with Aspergillus fumigatus, the most common pathogenic mold. We identified a novel, pyrimidine-based chemical scaffold with broad-spectrum antifungal activity including activity against several difficult-to-treat molds. A chemical genetics screen of Saccharomyces cerevisiae suggested that this compound may target the endoplasmic reticulum (ER) and perturb ER function and/or homeostasis. Consistent with this model, this compound induces the unfolded protein response and inhibits secretion of A. fumigatus collagenases. Initial cytotoxicity and pharmacokinetic studies show favorable features including limited mammalian cell toxicity and bioavailability in vivo. Together, these data support the further medicinal chemistry and pre-clinical development of this pyrimidine scaffold toward more effective treatments for life-threatening invasive mold infections.IMPORTANCEInvasive fungal diseases are life-threatening infections caused by fungi in immunocompromised individuals. Currently, there are only three major classes of antifungal drugs available to treat fungal infections; however, these options are becoming even more limited with the global emergence of antifungal drug resistance. To address the need for new antifungal therapies, we performed a screen of chemical compounds and identified a novel molecule with antifungal activity. Initial characterization of this compound shows drug-like features and broad-spectrum activity against medically important fungi. Together, our results support the continued development of this compound as a potential future therapy for these devastating fungal infections.
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Affiliation(s)
- Martin T Kelty
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Aracely Miron-Ocampo
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Sarah R Beattie
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
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Ross RL, Santiago-Tirado FH. Advanced genetic techniques in fungal pathogen research. mSphere 2024; 9:e0064323. [PMID: 38470131 PMCID: PMC11036804 DOI: 10.1128/msphere.00643-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2024] Open
Abstract
Although fungi have been important model organisms for solving genetic, molecular, and ecological problems, recently, they are also becoming an important source of infectious disease. Despite their high medical burden, fungal pathogens are understudied, and relative to other pathogenic microbes, less is known about how their gene functions contribute to disease. This is due, in part, to a lack of powerful genetic tools to study these organisms. In turn, this has resulted in inappropriate treatments and diagnostics and poor disease management. There are a variety of reasons genetic studies were challenging in pathogenic fungi, but in recent years, most of them have been overcome or advances have been made to circumvent these barriers. In this minireview, we highlight how recent advances in genetic studies in fungal pathogens have resulted in the discovery of important biology and potential new antifungals and have created the tools to comprehensively study these important pathogens.
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Affiliation(s)
- Robbi L. Ross
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | - Felipe H. Santiago-Tirado
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, USA
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA
- Warren Center for Drug Discovery, University of Notre Dame, Notre Dame, Indiana, USA
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Jones JT, Morelli KA, Vesely EM, Puerner CTS, Pavuluri CK, Ross BS, van Rhijn N, Bromley MJ, Cramer RA. The cystic fibrosis treatment Trikafta affects the growth, viability, and cell wall of Aspergillus fumigatus biofilms. mBio 2023; 14:e0151623. [PMID: 37830825 PMCID: PMC10653927 DOI: 10.1128/mbio.01516-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 09/01/2023] [Indexed: 10/14/2023] Open
Abstract
IMPORTANCE PwCF commonly test positive for pathogenic fungi, and more than 90% of the cystic fibrosis patient population is approved for the modulator treatment, Trikafta. Therefore, it is critical to understand how fungal communities, specifically A. fumigatus, respond to Trikafta exposure. Therefore, we sought to determine whether Trikafta impacted the biology of A. fumigatus biofilms. Our data demonstrate that Trikafta reduces biomass in several laboratory strains as well as clinical strains isolated from the expectorated sputum of pwCF. Furthermore, Trikafta reduces fungal viability and the capacity of biofilms to recover following treatment. Of particular importance, Trikafta affects how A. fumigatus biofilms respond to cell wall stressors, suggesting that Trikafta modulates components of the cell wall. Since the cell wall directly affects how a host immune system will respond to and effectively neutralize pathogens, our work, demonstrating that Trikafta impacts the A. fumigatus cell wall, is potentially highly relevant to fungal-induced disease pathogenesis.
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Affiliation(s)
- Jane T. Jones
- Department of Microbiology and Immunology, Dartmouth Geisel School of Medicine, Hanover, New Hampshire, USA
| | - Kaesi A. Morelli
- Department of Microbiology and Immunology, Dartmouth Geisel School of Medicine, Hanover, New Hampshire, USA
| | - Elisa M. Vesely
- Department of Microbiology and Immunology, Dartmouth Geisel School of Medicine, Hanover, New Hampshire, USA
| | - Charles T. S. Puerner
- Department of Microbiology and Immunology, Dartmouth Geisel School of Medicine, Hanover, New Hampshire, USA
| | - Chetan K. Pavuluri
- Department of Microbiology and Immunology, Dartmouth Geisel School of Medicine, Hanover, New Hampshire, USA
| | - Brandon S. Ross
- Department of Microbiology and Immunology, Dartmouth Geisel School of Medicine, Hanover, New Hampshire, USA
| | - Norman van Rhijn
- Manchester Fungal Infection Group, Division of Evolution, Infection, and Genomics, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
- Antimicrobial Resistance Network, University of Manchester, Manchester, United Kingdom
| | - Michael J. Bromley
- Manchester Fungal Infection Group, Division of Evolution, Infection, and Genomics, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
- Antimicrobial Resistance Network, University of Manchester, Manchester, United Kingdom
| | - Robert A. Cramer
- Department of Microbiology and Immunology, Dartmouth Geisel School of Medicine, Hanover, New Hampshire, USA
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Beattie SR, Esan T, Zarnowski R, Eix E, Nett JE, Andes DR, Hagen T, Krysan DJ. Novel Keto-Alkyl-Pyridinium Antifungal Molecules Active in Models of In Vivo Candida albicans Vascular Catheter Infection and Ex Vivo Candida auris Skin Colonization. Antimicrob Agents Chemother 2023; 67:e0008123. [PMID: 37097144 PMCID: PMC10190616 DOI: 10.1128/aac.00081-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/10/2023] [Indexed: 04/26/2023] Open
Abstract
New antifungal therapies are needed for both systemic, invasive infections in addition to superficial infections of mucosal and skin surfaces as well as biofilms associated with medical devices. The resistance of biofilm and biofilm-like growth phases of fungi contributes to the poor efficacy of systemic therapies to nonsystemic infections. Here, we describe the identification and characterization of a novel keto-alkyl-pyridinium scaffold with broad spectrum activity (2 to 16 μg/mL) against medically important yeasts and molds, including clinical isolates resistant to azoles and/or echinocandins. Furthermore, these keto-alkyl-pyridinium agents retain substantial activity against biofilm phase yeast and have direct activity against hyphal A. fumigatus. Although their toxicity precludes use in systemic infections, we found that the keto-alkyl-pyridinium molecules reduce Candida albicans fungal burden in a rat model of vascular catheter infection and reduce Candida auris colonization in a porcine ex vivo model. These initial preclinical data suggest that molecules of this class may warrant further study and development for nonsystemic applications.
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Affiliation(s)
- Sarah R. Beattie
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Taiwo Esan
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois, USA
| | - Robert Zarnowski
- Department of Medicine, Section of Infectious Disease, University of Wisconsin, Madison, Wisconsin, USA
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison Wisconsin, USA
| | - Emily Eix
- Department of Medicine, Section of Infectious Disease, University of Wisconsin, Madison, Wisconsin, USA
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison Wisconsin, USA
| | - Jeniel E. Nett
- Department of Medicine, Section of Infectious Disease, University of Wisconsin, Madison, Wisconsin, USA
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison Wisconsin, USA
| | - David R. Andes
- Department of Medicine, Section of Infectious Disease, University of Wisconsin, Madison, Wisconsin, USA
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison Wisconsin, USA
| | - Timothy Hagen
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois, USA
| | - Damian J. Krysan
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Microbiology/Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
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Novel keto-alkyl-pyridinium antifungal molecules active in models of in vivo Candida albicans vascular catheter infection and ex vivo Candida auris skin colonization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.19.524835. [PMID: 36711909 PMCID: PMC9882332 DOI: 10.1101/2023.01.19.524835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
New antifungal therapies are needed for both systemic, invasive infections as well as superficial infections of mucosal and skin surfaces as well as biofilms associated with medical devices. The resistance of biofilm and biofilm-like growth phases of fungi contributes to the poor efficacy of systemic therapies to non-systemic infections. Here, we describe the identification and characterization of a novel keto-alkyl-pyridinium scaffold with broad spectrum activity (2-16 µg/mL) against medically important yeasts and moulds, including clinical isolates resistant to azoles and/or echinocandins. Furthermore, these keto-alkyl-pyridinium agents retain substantial activity against biofilm phase yeast and have direct activity against hyphal A. fumigatus . Although their toxicity precludes use in systemic infections, we found that the keto-alkyl-pyridinium molecules reduce C. albicans fungal burden in a rat model of vascular catheter infection and reduce Candida auris colonization in a porcine ex vivo model. These initial pre-clinical data suggest that molecules of this class may warrant further study and development.
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Beattie SR, Krysan DJ. A Dual-Readout High-Throughput Screening Assay for Small Molecules Active Against Aspergillus Fumigatus. Methods Mol Biol 2023; 2658:35-42. [PMID: 37024693 DOI: 10.1007/978-1-0716-3155-3_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
Abstract
Human fungal infections caused by molds have been on the rise in recent years. These infections have high mortality rates compared to other fungal infections, and yet treatment options are limited due to resistance to clinical antifungals and lack of broad-spectrum activity against molds. Technical challenges associated with molds have limited large-throughput screening efforts for anti-mold compounds: therefore, we adapted an assay for use with A. fumigatus to help fill the gap in robust screening platforms for these organisms. This assay measures the release of the cytosolic enzyme adenylate kinase (AK) as a measure of fungal cell lysis and can also detect inhibition of germination as a reduction in the secretion of AK during vegetative growth. The ability to detect both lysis and inhibition of germination facilitates the identification of a wide range of compounds with different mechanisms of action, creating a strong screening platform for the identification of novel, anti-mold compounds.
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Affiliation(s)
- Sarah R Beattie
- Departments of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
| | - Damian J Krysan
- Departments of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
- Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
- Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
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Kerkaert JD, Le Mauff F, Wucher BR, Beattie SR, Vesely EM, Sheppard DC, Nadell CD, Cramer RA. An Alanine Aminotransferase Is Required for Biofilm-Specific Resistance of Aspergillus fumigatus to Echinocandin Treatment. mBio 2022; 13:e0293321. [PMID: 35254131 PMCID: PMC9040767 DOI: 10.1128/mbio.02933-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 02/08/2022] [Indexed: 12/21/2022] Open
Abstract
Alanine metabolism has been suggested as an adaptation strategy to oxygen limitation in organisms ranging from plants to mammals. Within the pulmonary infection microenvironment, Aspergillus fumigatus forms biofilms with steep oxygen gradients defined by regions of oxygen limitation. An alanine aminotransferase, AlaA, was observed to function in alanine catabolism and is required for several aspects of A. fumigatus biofilm physiology. Loss of alaA, or its catalytic activity, results in decreased adherence of biofilms through a defect in the maturation of the extracellular matrix polysaccharide galactosaminogalactan (GAG). Additionally, exposure of cell wall polysaccharides is also impacted by loss of alaA, and loss of AlaA catalytic activity confers increased biofilm susceptibility to echinocandin treatment, which is correlated with enhanced fungicidal activity. The increase in echinocandin susceptibility is specific to biofilms, and chemical inhibition of alaA by the alanine aminotransferase inhibitor β-chloro-l-alanine is sufficient to sensitize A. fumigatus biofilms to echinocandin treatment. Finally, loss of alaA increases susceptibility of A. fumigatus to in vivo echinocandin treatment in a murine model of invasive pulmonary aspergillosis. Our results provide insight into the interplay of metabolism, biofilm formation, and antifungal drug resistance in A. fumigatus and describe a mechanism of increasing susceptibility of A. fumigatus biofilms to the echinocandin class of antifungal drugs. IMPORTANCE Aspergillus fumigatus is a ubiquitous filamentous fungus that causes an array of diseases depending on the immune status of an individual, collectively termed aspergillosis. Antifungal therapy for invasive pulmonary aspergillosis (IPA) or chronic pulmonary aspergillosis (CPA) is limited and too often ineffective. This is in part due to A. fumigatus biofilm formation within the infection environment and the resulting emergent properties, particularly increased antifungal resistance. Thus, insights into biofilm formation and mechanisms driving increased antifungal drug resistance are critical for improving existing therapeutic strategies and development of novel antifungals. In this work, we describe an unexpected observation where alanine metabolism, via the alanine aminotransferase AlaA, is required for several aspects of A. fumigatus biofilm physiology, including resistance of A. fumigatus biofilms to the echinocandin class of antifungal drugs. Importantly, we observed that chemical inhibition of alanine aminotransferases is sufficient to increase echinocandin susceptibility and that loss of alaA increases susceptibility to echinocandin treatment in a murine model of IPA. AlaA is the first gene discovered in A. fumigatus that confers resistance to an antifungal drug specifically in a biofilm context.
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Affiliation(s)
- Joshua D. Kerkaert
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - François Le Mauff
- Department of Microbiology and Immunology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
- Infectious Disease and Immunity in Global Health, Research Institute of McGill University Health Center, Montreal, Quebec, Canada
- McGill Interdisciplinary Initiative in Infection and Immunity, Montreal, Quebec, Canada
| | - Benjamin R. Wucher
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
| | - Sarah R. Beattie
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Elisa M. Vesely
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Donald C. Sheppard
- Department of Microbiology and Immunology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
- Infectious Disease and Immunity in Global Health, Research Institute of McGill University Health Center, Montreal, Quebec, Canada
- McGill Interdisciplinary Initiative in Infection and Immunity, Montreal, Quebec, Canada
| | - Carey D. Nadell
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
| | - Robert A. Cramer
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
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Yoshimi A, Miyazawa K, Kawauchi M, Abe K. Cell Wall Integrity and Its Industrial Applications in Filamentous Fungi. J Fungi (Basel) 2022; 8:jof8050435. [PMID: 35628691 PMCID: PMC9148135 DOI: 10.3390/jof8050435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 04/15/2022] [Accepted: 04/20/2022] [Indexed: 11/20/2022] Open
Abstract
Signal transduction pathways regulating cell wall integrity (CWI) in filamentous fungi have been studied taking into account findings in budding yeast, and much knowledge has been accumulated in recent years. Given that the cell wall is essential for viability in fungi, its architecture has been analyzed in relation to virulence, especially in filamentous fungal pathogens of plants and humans. Although research on CWI signaling in individual fungal species has progressed, an integrated understanding of CWI signaling in diverse fungi has not yet been achieved. For example, the variety of sensor proteins and their functional differences among different fungal species have been described, but the understanding of their general and species-specific biological functions is limited. Our long-term research interest is CWI signaling in filamentous fungi. Here, we outline CWI signaling in these fungi, from sensor proteins required for the recognition of environmental changes to the regulation of cell wall polysaccharide synthesis genes. We discuss the similarities and differences between the functions of CWI signaling factors in filamentous fungi and in budding yeast. We also describe the latest findings on industrial applications, including those derived from studies on CWI signaling: the development of antifungal agents and the development of highly productive strains of filamentous fungi with modified cell surface characteristics by controlling cell wall biogenesis.
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Affiliation(s)
- Akira Yoshimi
- Laboratory of Environmental Interface Technology of Filamentous Fungi, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan; (A.Y.); (M.K.)
- ABE-Project, New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8579, Japan
| | - Ken Miyazawa
- ABE-Project, New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8579, Japan
- Laboratory of Filamentous Mycoses, Department of Fungal Infection, National Institute of Infectious Diseases, Tokyo 162-8640, Japan;
| | - Moriyuki Kawauchi
- Laboratory of Environmental Interface Technology of Filamentous Fungi, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan; (A.Y.); (M.K.)
| | - Keietsu Abe
- ABE-Project, New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8579, Japan
- Laboratory of Applied Microbiology, Graduate School of Agricultural Science, Tohoku University, Sendai 980-8572, Japan
- Correspondence: ; Tel.: +81-22-757-4355
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Miyazawa K, Umeyama T, Hoshino Y, Abe K, Miyazaki Y. Quantitative Monitoring of Mycelial Growth of Aspergillus fumigatus in Liquid Culture by Optical Density. Microbiol Spectr 2022; 10:e0006321. [PMID: 34985327 PMCID: PMC8729762 DOI: 10.1128/spectrum.00063-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 11/17/2021] [Indexed: 01/24/2023] Open
Abstract
Filamentous fungi form multicellular hyphae, which generally form pellets in liquid shake cultures, during the vegetative growth stage. Because of these characteristics, growth-monitoring methods commonly used in bacteria and yeast have not been applied to filamentous fungi. We have recently revealed that the cell wall polysaccharide α-1,3-glucan and extracellular polysaccharide galactosaminogalactan (GAG) contribute to hyphal aggregation in Aspergillus oryzae. Here, we tested whether Aspergillus fumigatus shows dispersed growth in liquid media that can be quantitatively monitored, similar to that of yeasts. We constructed a double disruptant mutant of both the primary α-1,3-glucan synthase gene ags1 and the putative GAG synthase gene gtb3 in A. fumigatus AfS35 and found that the hyphae of this mutant were fully dispersed. Although the mutant lost α-1,3-glucan and GAG, its growth and susceptibility to antifungal agents were not different from those of the parental strain. Mycelial weight of the mutant in shake-flask cultures was proportional to optical density for at least 18 h. We were also able to quantify the dose response of hyphal growth to antifungal agents by measuring optical density. Overall, we established a convenient strategy to monitor A. fumigatus hyphal growth. Our method can be directly used for screening for novel antifungals against Aspergillus species. IMPORTANCE Filamentous fungi generally form hyphal pellets in liquid culture. This property prevents filamentous fungi so that we may apply the methods used for unicellular organisms such as yeast and bacteria. In the present study, by using the fungal pathogen Aspergillus fumigatus strain with modified hyphal surface polysaccharides, we succeeded in monitoring the hyphal growth quantitatively by optical density. The principle of this easy measurement by optical density could lead to a novel standard of hyphal quantification such as those that have been used for yeasts and bacteria. Dose response of hyphal growth by antifungal agents could also be monitored. This method could be useful for screening for novel antifungal reagents against Aspergillus species.
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Affiliation(s)
- Ken Miyazawa
- Department of Fungal Infection, National Institute of Infectious Diseases, Tokyo, Japan
| | - Takashi Umeyama
- Department of Fungal Infection, National Institute of Infectious Diseases, Tokyo, Japan
| | - Yasutaka Hoshino
- Department of Fungal Infection, National Institute of Infectious Diseases, Tokyo, Japan
| | - Keietsu Abe
- Laboratory of Applied Microbiology, Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Yoshitsugu Miyazaki
- Department of Fungal Infection, National Institute of Infectious Diseases, Tokyo, Japan
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