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Ahmed F, Mirani ZA, Urooj S, Noor Ul Hudda H, Janees Imdad M, Zhao Y, Malakar PK. A rare biofilm dispersion strategy demonstrated by Staphylococcus aureus under oxacillin stress. Microb Pathog 2024; 194:106838. [PMID: 39111368 DOI: 10.1016/j.micpath.2024.106838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Revised: 07/31/2024] [Accepted: 08/02/2024] [Indexed: 08/13/2024]
Abstract
Staphylococcus aureus (S. aureus), a versatile Gram-positive bacterium, is implicated in a spectrum of infections, and its resilience is often attributed to biofilm formation. This study investigates the effect of sub-inhibitory doses of oxacillin on biofilm formation by methicillin-resistant S. aureus (MRSA). Specifically, it examines how these doses influence biofilms' development, maturation, and dispersal. The biofilm's zenith reached 48 h of incubation, followed by a noteworthy decline at 96 h and a distinctive clearance zone around biofilm-positive cells exposed to oxacillin. Scanning electron micrographs unveiled an intriguing active biofilm dispersal mechanism, a rarity in this species. Among 180 isolates, only three carrying the elusive icaD gene exhibited this phenomenon. icaD gene was absent in their counterparts. Notably, the icaD gene emerges as a distinctive marker, crucial in regulating biofilm dispersion and setting these isolates apart. The captivating interplay of oxacillin, biofilm dynamics, and genetic signatures disintegrate novel dimensions in understanding MRSA's adaptive strategies and underscores the importance of the icaD gene in engineering biofilm resilience.
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Affiliation(s)
- Faraz Ahmed
- College of Food Science and Technology, Shanghai Ocean University, Shanghai, China; International Research Centre for Food and Health, Shanghai Ocean University, Shanghai, China.
| | - Zulfiqar Ali Mirani
- Microbiology Section, FMRRC, PCSIR Laboratories Complex Karachi, Sindh, Pakistan
| | - Shaista Urooj
- Aquatic Diagnostic and Research Center Bahria University, Karachi, Sindh, Pakistan
| | | | - Muhammad Janees Imdad
- College of Food Science and Technology, Shanghai Ocean University, Shanghai, China; International Research Centre for Food and Health, Shanghai Ocean University, Shanghai, China
| | - Yong Zhao
- College of Food Science and Technology, Shanghai Ocean University, Shanghai, China; International Research Centre for Food and Health, Shanghai Ocean University, Shanghai, China; Laboratory of Quality & Safety Risk Assessment for Aquatic Products on Storage and Preservation (Shanghai), Ministry of Agriculture and Rural Affairs, Shanghai, China; Shanghai Engineering Research Center of Aquatic-Product Processing & Preservation, Shanghai, China
| | - Pradeep K Malakar
- College of Food Science and Technology, Shanghai Ocean University, Shanghai, China; International Research Centre for Food and Health, Shanghai Ocean University, Shanghai, China.
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Puerner C, Vellanki S, Strauch JL, Cramer RA. Recent Advances in Understanding the Human Fungal Pathogen Hypoxia Response in Disease Progression. Annu Rev Microbiol 2023; 77:403-425. [PMID: 37713457 PMCID: PMC11034785 DOI: 10.1146/annurev-micro-032521-021745] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/17/2023]
Abstract
Fungal-mediated disease progression and antifungal drug efficacy are significantly impacted by the dynamic infection microenvironment. At the site of infection, oxygen often becomes limiting and induces a hypoxia response in both the fungal pathogen and host cells. The fungal hypoxia response impacts several important aspects of fungal biology that contribute to pathogenesis, virulence, antifungal drug susceptibility, and ultimately infection outcomes. In this review, we summarize recent advances in understanding the molecular mechanisms of the hypoxia response in the most common human fungal pathogens, discuss potential therapeutic opportunities, and highlight important areas for future research.
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Affiliation(s)
- Charles Puerner
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA;
| | - Sandeep Vellanki
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA;
| | - Julianne L Strauch
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA;
- Department of Biology, 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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Rajasenan S, Osmani AH, Osmani SA. Modulation of sensitivity to gaseous signaling by sterol-regulatory hypoxic transcription factors in Aspergillus nidulans biofilm cells. Fungal Genet Biol 2022; 163:103739. [PMID: 36089227 DOI: 10.1016/j.fgb.2022.103739] [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: 05/20/2022] [Revised: 08/15/2022] [Accepted: 09/05/2022] [Indexed: 01/06/2023]
Abstract
Fungal biofilm founder cells experience self-generated hypoxia leading to dramatic changes in their cell biology. For example, during Aspergillus nidulans biofilm formation microtubule (MT) disassembly is triggered causing dispersal of EB1 from MT tips. This process is dependent on SrbA, a sterol regulatory element-binding transcription factor required for adaptation to hypoxia. We show that SrbA, an ER resident protein prior to activation, is proteolytically activated during early stages of biofilm formation and that, like SrbA itself, its activating proteases are also required for normal biofilm MT disassembly. In addition to SrbA, the AtrR transcription factor is also found to be required to modulate cellular responses to gaseous signaling during biofilm development. Using co-cultures, we further show that cells lacking srbA or atrR are capable of responding to biofilm generated gaseous microenvironments but are actually more sensitive to this signal than wild type cells. SrbA is a regulator of ergosterol biosynthetic genes and we find that the levels of seven GFP-tagged Erg proteins differentially accumulate during biofilm formation with various dependencies on SrbA for their accumulation. This uncovers a complex pattern of regulation with biofilm accumulation of only some Erg proteins being dependent on SrbA with others accumulating to higher levels in its absence. Because different membrane sterols are known to influence cell permeability to gaseous molecules, including oxygen, we propose that differential regulation of ergosterol biosynthetic proteins by SrbA potentially calibrates the cell's responsiveness to gaseous signaling which in turn modifies the cell biology of developing biofilm cells.
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Affiliation(s)
- Shobhana Rajasenan
- Ohio State University, Department of Molecular Genetics, 105 Biological Sciences Building, 484 West 12th Avenue, Columbus, OH 43210, United States
| | - Aysha H Osmani
- Ohio State University, Department of Molecular Genetics, 105 Biological Sciences Building, 484 West 12th Avenue, Columbus, OH 43210, United States
| | - Stephen A Osmani
- Ohio State University, Department of Molecular Genetics, 105 Biological Sciences Building, 484 West 12th Avenue, Columbus, OH 43210, United States.
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Cortesão M, Holland G, Schütze T, Laue M, Moeller R, Meyer V. Colony growth and biofilm formation of Aspergillus niger under simulated microgravity. Front Microbiol 2022; 13:975763. [PMID: 36212831 PMCID: PMC9539656 DOI: 10.3389/fmicb.2022.975763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 08/30/2022] [Indexed: 11/20/2022] Open
Abstract
The biotechnology- and medicine-relevant fungus Aspergillus niger is a common colonizer of indoor habitats such as the International Space Station (ISS). Being able to colonize and biodegrade a wide range of surfaces, A. niger can ultimately impact human health and habitat safety. Surface contamination relies on two key-features of the fungal colony: the fungal spores, and the vegetative mycelium, also known as biofilm. Aboard the ISS, microorganisms and astronauts are shielded from extreme temperatures and radiation, but are inevitably affected by spaceflight microgravity. Knowing how microgravity affects A. niger colony growth, in particular regarding the vegetative mycelium (biofilm) and spore production, will help prevent and control fungal contaminations in indoor habitats on Earth and in space. Because fungal colonies grown on agar can be considered analogs for surface contamination, we investigated A. niger colony growth on agar in normal gravity (Ground) and simulated microgravity (SMG) conditions by fast-clinorotation. Three strains were included: a wild-type strain, a pigmentation mutant (ΔfwnA), and a hyperbranching mutant (ΔracA). Our study presents never before seen scanning electron microscopy (SEM) images of A. niger colonies that reveal a complex ultrastructure and biofilm architecture, and provide insights into fungal colony development, both on ground and in simulated microgravity. Results show that simulated microgravity affects colony growth in a strain-dependent manner, leading to thicker biofilms (vegetative mycelium) and increased spore production. We suggest that the Rho GTPase RacA might play a role in A. niger’s adaptation to simulated microgravity, as deletion of ΔracA leads to changes in biofilm thickness, spore production and total biomass. We also propose that FwnA-mediated melanin production plays a role in A. niger’s microgravity response, as ΔfwnA mutant colonies grown under SMG conditions showed increased colony area and spore production. Taken together, our study shows that simulated microgravity does not inhibit A. niger growth, but rather indicates a potential increase in surface-colonization. Further studies addressing fungal growth and surface contaminations in spaceflight should be conducted, not only to reduce the risk of negatively impacting human health and spacecraft material safety, but also to positively utilize fungal-based biotechnology to acquire needed resources in situ.
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Affiliation(s)
- Marta Cortesão
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Radiation Biology Department, Aerospace Microbiology Research Group, Cologne, Germany
- Chair of Applied and Molecular Microbiology, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
- *Correspondence: Marta Cortesão,
| | - Gudrun Holland
- Robert Koch Institute, Advanced Light and Electron Microscopy (ZBS 4), Berlin, Germany
| | - Tabea Schütze
- Chair of Applied and Molecular Microbiology, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
| | - Michael Laue
- Robert Koch Institute, Advanced Light and Electron Microscopy (ZBS 4), Berlin, Germany
| | - Ralf Moeller
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Radiation Biology Department, Aerospace Microbiology Research Group, Cologne, Germany
| | - Vera Meyer
- Chair of Applied and Molecular Microbiology, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
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Corrêa-Almeida C, Borba-Santos LP, Rollin-Pinheiro R, Barreto-Bergter E, Rozental S, Kurtenbach E. Characterization of Aspergillus nidulans Biofilm Formation and Structure and Their Inhibition by Pea Defensin Psd2. Front Mol Biosci 2022; 9:795255. [PMID: 35155575 PMCID: PMC8830917 DOI: 10.3389/fmolb.2022.795255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 01/11/2022] [Indexed: 11/13/2022] Open
Abstract
Approximately four million people contract fungal infections every year in Brazil, primarily caused by Aspergillus spp. The ability of these fungi to form biofilms in tissues and medical devices complicates treatment and contributes to high rates of morbidity and mortality in immunocompromised patients. Psd2 is a pea defensin of 5.4 kDa that possesses good antifungal activity against planktonic cells of representative pathogenic fungi. Its function depends on interactions with membrane and cell wall lipid components such as glucosylceramide and ergosterol. In the present study, we characterized Aspergillus nidulans biofilm formation and determined the effect of Psd2 on A. nidulans biofilms. After 4 hours, A. nidulans conidia adhered to polystyrene surfaces and formed a robust extracellular matrix-producing biofilm at 24 h, increasing thickness until 48 h Psd2 inhibited A. nidulans biofilm formation in a dose-dependent manner. Most notably, at 10 μM Psd2 inhibited 50% of biofilm viability and biomass and 40% of extracellular matrix production. Psd2 significantly decreased the colonized surface area by the biofilm and changed its level of organization, causing a shortening of length and diameter of hyphae and inhibition of conidiophore formation. This activity against A. nidulans biofilm suggests a potential use of Psd2 as a prototype to design new antifungal agents to prevent biofilm formation by A. nidulans and related species.
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Affiliation(s)
- Caroline Corrêa-Almeida
- Laboratório de Biologia Molecular e Bioquímica de Proteínas, Programa de Biologia Molecular e Estrutural, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brasil
| | - Luana P. Borba-Santos
- Laboratório de Biologia Celular de Fungos, Programa de Parasitologia e Biologia Celular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brasil
| | - Rodrigo Rollin-Pinheiro
- Laboratório de Química Biológica de Microrganismos, Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brasil
| | - Eliana Barreto-Bergter
- Laboratório de Química Biológica de Microrganismos, Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brasil
| | - Sonia Rozental
- Laboratório de Biologia Celular de Fungos, Programa de Parasitologia e Biologia Celular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brasil
| | - Eleonora Kurtenbach
- Laboratório de Biologia Molecular e Bioquímica de Proteínas, Programa de Biologia Molecular e Estrutural, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brasil
- *Correspondence: Eleonora Kurtenbach,
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