Effects of Ultraviolet Exposure on the Tropical Fungi Aspergillus carbonarius and Aspergillus japonicus: Survival, Amylase Production, and Thermostability

Abstract

Background and Research Aims Although fundamental to tropical forest biodiversity, fungi have been largely neglected in conservation research. To examine the fungal response to increased ultraviolet C (UVC) radiation, we analyzed UVC radiation effects on the survival, growth, and amylase activity of Aspergillus carbonarius and Aspergillus japonicus. Methods A. carbonarius (strain URM 7305) and A. japonicus (URM 7270) were exposed to UVC (254 nm) for different periods, and morphological changes were compared to the control. Results Survival capacity and growth decreased after 10 min of exposure in A. carbonarius and after 25 min in A. japonicus. After 40 min, amylase activity decreased (A. carbonarius: 35.8%; A. japonicus: 30.3%). Amylase thermostability at 60°C was lower in UVC-exposed strains (T50 15 min) compared to controls (A. japonicus, 45 min; A. carbonarius, 30 min). However, the protein amount remained stable in all UVC-treated strains. Contamination by other fungi was observed in the UVC-exposed strains, confirming competitive strength loss in both species. This was not observed in the controls due to secondary metabolite production, which increased their competitive fitness. Conclusion We provide new information about UVC’s adverse effects on the survival and enzyme production of A. carbonarius and A. japonicus, which could mean a loss of species essential for proper soil functioning and biodiversity. Implications for conservation Experimental manipulation of biochemical and physiological reactions advances fungal conservation beyond distributional data. The experimental evidence supports previous studies, suggesting that the increased UV radiation caused by climate change may drastically affect fungal biochemistry and physiology.