The Effect of Temperature over the Growth and Biofilm Formation of the Thermotolerant Aspergillus flavus

• Published in: Journal of fungi (Basel) 2025-01, Vol.11 (1), p.53
• Main Authors: Hernández-Benítez, José Alejandro, Santos-Ocampo, Brenda Nallely, Rosas-Ramírez, Daniel Genaro, Bautista-Hernández, Luis Antonio, Bautista-de Lucio, Víctor Manuel, Pérez, Néstor Octavio, Rodríguez-Tovar, Aída Verónica
• Format: Article
• Language: English
• Subjects: Aflatoxins; Amphotericin B; Antifungal agents; antifungal susceptibility; Aspergillosis; Aspergillus flavus; biofilm; Biofilms; Carbohydrates; Extracellular matrix; Fungi; Germination; Hyphae; Infections; Itraconazole; lipid droplets; Microorganisms; Opportunist infection; Pathogens; Temperature; Temperature effects; Temperature tolerance; thermotolerant; Tropical environment; Virulence
• ISSN: 2309-608X; 2309-608X
• DOI: 10.3390/jof11010053

is a medically relevant fungus, particularly in tropical regions. Although its aflatoxin production and thermotolerance are well documented, its biofilm-forming ability has received less attention, despite being a key factor in the virulence of as an opportunistic pathogen, which can significantly impact therapeutic outcomes. To investigate the influence of temperature on the growth and biofilm formation of an isolate, we compared it on solid media with the reference strain ATCC 22546 and documented morphological changes during conidial germination. We examined biofilm formation in both strains across different temperatures and evaluated the susceptibility of this isolate to antifungal agents in both planktonic and biofilm form. Our results showed that the temperature can promote conidiation on solid media. Radial growth was highest at 28 °C, while the conidial count and density were favored at higher temperatures. Moreover, we determined that 37 °C was the optimal temperature for conidial germination and biofilm formation. We described four distinct phases in biofilm development-initiation (0-12 h), consolidation (12-24 h), maturation (24-48 h), and dispersion (48-72 h)-with the notable presence of conidial heads at 42 °C. Carbohydrates and proteins constitute the primary components of the extracellular matrix. We observed an abundance of lipid droplets within the hyphae of the MMe18 strain biofilm. The mature biofilms demonstrated reduced susceptibility to amphotericin B and itraconazole, requiring higher inhibitory concentrations for both antifungals compared with their planktonic counterparts.