Coniochaeta fungus benefits from its intracellular bacteria to form biofilm and defend against other fungi

• Published in: Archives of microbiology Vol. 203; no. 4; pp. 1357 - 1366
• Main Authors: Heydari, Samira, Siavoshi, Farideh, Sarrafnejad, Abdolfattah, Malekzadeh, Reza
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-05-2021; Springer Nature B.V
• Subjects: Antifungal Agents - metabolism; Antifungal Agents - pharmacology; Ascomycota - metabolism; Ascomycota - physiology; Ascomycota - ultrastructure; Bacteria; Biochemistry; Biofilms; Biofilms - growth & development; Biomedical and Life Sciences; Biotechnology; Candida - drug effects; Cell Biology; Cell culture; Cytoplasm; Cytoplasm - microbiology; Ecology; Electron microscopy; Field emission microscopy; Fluorescence; Fungi; Fungicides; Fungiculture; Intracellular; Life Sciences; Microbial Ecology; Microbial Interactions; Microbiology; Micrography; Microorganisms; Microscopy; Microscopy, Electron, Scanning; Monoculture; Nocardia; Nocardia - isolation & purification; Nocardia - physiology; Nocardia - ultrastructure; Original Paper; Photomicrographs; Scanning electron microscopy; Slime; Intracellular bacteria; Biofilm; Antibiotic production; fungus; Bacterial-fungal interactions; Coniochaeta fungus
• ISSN: 0302-8933; 1432-072X
• DOI: 10.1007/s00203-020-02122-4

During cultivation of a gastric fungus,
Coniochaeta polymorpha
, growth of
Nocardia
colonies on top of the fungal culture raised the question whether bacteria originated from inside of fungus. In this study, the likelihood of intracellular origin of bacteria as well as interaction of two microorganisms was assessed. Fluorescence and electron microscopy showed occurrence of several bacterial cells in fungal cytoplasm. A thick biofilm was observed on the surface of co-culture compared with thin one on bacterial and none on fungal monocultures. Field emission scanning electron microscopy (FESEM) micrographs of co-culture showed a dense network of fungal and bacterial cells embedded in a slime-like layer. Dual cultures revealed antagonistic activity of both fungus and bacteria against three
Candida
species. These findings indicate that
Nocardia
isolate identified in this study originated from the inside of fungus
C. polymorpha
. Intracellular bacteria could benefit the fungal host by producing a rigid biofilm and an antifungal compound.