Role of arthroconidia in biofilm formation by Trichosporon asahii

Abstract

Background: Trichosporon asahii is the major causative agent of disseminated and deep-seated trichosporonosis. It is capable of forming biofilms on surfaces, leading to medical device-related infection. Trichosporon asahii may be present as yeast form, hyphae and/or arthroconidia; however, the relationship between its biofilm-forming ability and its morphological transition is unclear. Objectives: We investigated whether the T. asahii morphological transition contributes to its biofilm formation. We also determined the conditions required to induce each of the morphologies. Methods: Three high-and three low-biofilm-producing strains (HBS and LBS, respectively) were selected using a biofilm formation assay, and the cell surface hydrophobicity of these six strains was measured. For each strain, the morphology was observed and the number of each morphological form (yeast form, hypha and arthroconidium) was counted to calculate the ratio. Finally, the ability of cells each morphological type to adhere to the polystyrene substrate was evaluated. Results: The HBS exhibited abundant arthroconidia and hyphae; in contrast, the LBS produced mainly hyphae with few or no arthroconidia. The production of hyphae was increased by nitrogen-containing medium, and the production of arthroconidia was increased by nitrogen-deficient medium. Cells incubated under nitrogen-deficient conditions showed higher adherence to a polystyrene surface than those incubated in the presence of nitrogen. Conclusion: Arthroconidia of T. asahii play a key role in biofilm formation by promoting cellular adhesion.

Dimorphism in Neopseudocercosporella capsellae, an Emerging Pathogen Causing White Leaf Spot Disease of Brassicas

“…In the literature, polymorphism is defined as the ability of a fungus to take more than two different morphological forms (Mayer et al, 2013). Candida albicans provides a classic example for polymorphic pathogenic fungi, where it can form biofilms, different morphotypes for the single-celled blastospores (yeast phase), hyphae, and pseudo-hyphae (Odds and Kerridge, 1985;Kurakado et al, 2020). Formation of biofilm at the interface of yeast-to-hyphae transition was also observed for N. capsellae in this study.…”

“…However, the release of cylindrical arthrospores by autolysis of the original hyphal wall also occurred when arthrospores were produced from multi-celled macroconidia (Figure 10). There is evidence that arthrospores are a superior asexual spore type providing enhanced dissemination and better establishment on the host tissue by protecting cells from host lytic enzymes ( Duran et al, 1973), increasing antibiotic production (Nash and Huber, 1971;Queener and Ellis, 1975), and by promoting surface adherence (Kurakado et al, 2020).…”

“…Formation of biofilm at the interface of yeast-to-hyphae transition was also observed for N. capsellae in this study. It is known that biofilm development and morphogenesis are interconnected phenomena controlled by the same set of genes for a given species (Lin et al, 2015;Kurakado et al, 2020). Further studies are recommended not only to answer the question of whether N. capsellae is dimorphic or polymorphic but also to define the decisive role/s of each morphotype produced understanding its morphogenesis.…”

Development of an efficient gene-targeting system for elucidating infection mechanisms of the fungal pathogen Trichosporon asahii

“…T. asahii has morphological forms: yeast form, hyphae (filament form) and arthroconidia (chains of cells and asexual spores) 4 . Furthermore, arthroconidia of T. asahii may play a key role in biofilm formation by promoting cellular adhesion 15 . T. asahii is therefore a highly problematic clinical pathogen 9 .…”

Development of an Efficient Gene-targeting System for Elucidating Infection Mechanisms of the Fungal Pathogen Trichosporon Asahii

“…Culture of T. asahii. The T. asahii strains (MPU105, MPU107, MPU108, MPU113, MPU120, MPU129, MPU131, MPU133, MPU147, MPU153, MPU159, MPU160, MPU161, MPU162, MPU330, MPU331, and MPU344) used in this study were stocked in the previously reported MPU library 45 . T. asahii strains were grown on Sabouraud dextrose agar (1% hipolypepton [Nihon Pharmaceutical Co., Ltd., Tokyo, Japan], 4% dextrose and 1.5% agar [both from FUJIFILM Wako Pure Chemical Industries, Osaka, Japan]) and incubated at 27°C for 2 days.…”