Optimized Protocol for RNA Isolation from Penicillium spp. and Aspergillus fumigatus Strains

Efficient RNA isolation from filamentous fungi is crucial for gene expression studies, but it poses significant technical challenges due to the robust cell walls and susceptibility of RNA to degradation by ribonucleases. This study presents the effectiveness of two RNA isolation protocols for four species of filamentous fungi: Penicillium crustosum, Penicillium rubens, Penicillium griseofulvum, and Aspergillus fumigatus. Both protocols utilized Fenzol Plus for cell lysis but varied in the mechanical disruption methods: bead-beating versus manual vortexing. The results show that the bead-beater method (Protocol 1) yielded significantly higher RNA quantities, with better purity and integrity, as demonstrated by higher A260/A280 and A260/A230 ratios. RNA concentrations ranged from 30 to 96 µg/g of dry biomass in Penicillium species and up to 52 µg/g in A. fumigatus. The use of chloroform in Protocol 1 also enhanced RNA purity, effectively separating contaminants such as DNA, proteins, and polysaccharides. This optimized protocol is highly efficient and can be applied in routine laboratories handling large numbers of fungal samples, making it a robust method for downstream applications such as cDNA synthesis and transcriptome analysis.