Mucor lusitanicus and some other members of the fungal order Mucorales display the phenomenon of morphological dimorphism. This means that these fungi aerobically produce filamentous hyphae, developing a coenocytic mycelium, but they grow in a multipolar yeast-like form under anaerobiosis. Revealing the molecular mechanism of the reversible yeast-hyphal transition can be interesting for both the biotechnological application and in the understanding of the pathomechanism of mucormycosis. In the present study, transcriptomic analyses were carried out after cultivating the fungus either aerobically or anaerobically revealing significant changes in gene expression under the two conditions. In total, 539 differentially expressed genes (FDR < 0.05, |log₂FC| ≥ 3) were identified, including 190 upregulated and 349 downregulated transcripts. Within the metabolism-related genes, carbohydrate metabolism was proven to be especially affected. Anaerobiosis also affected the transcription of transporters: among the 14 up- and 42 downregulated transporters, several putative sugar transporters were detected. Moreover, a considerable number of transcripts related to amino acid transport and metabolism, lipid transport and metabolism, and energy production and conversion were proven to be downregulated when the culture had been transferred into an anaerobic atmosphere.

Lichtheimia corymbifera is considered as one of the most frequent agents of mucormycosis. The lack of efficient genetic manipulation tools hampers the characterization of the pathomechanisms and virulence factors of this opportunistic pathogenic fungus. Although such techniques have been described for certain species, the performance of targeted mutagenesis and the construction of stable transformants have remained a great challenge in Mucorales fungi. In the present study, a plasmid-free CRISPR-Cas9 system was applied to carry out a targeted gene disruption in L. corymbifera. The described method is based on the non-homologous end-joining repair of the double-strand break caused by the Cas9 enzyme. Using this method, short, one-to-five nucleotide long-targeted deletions could be induced in the orotidine 5′-phosphate decarboxylase gene (pyrG) and, as a result, uracil auxotrophic strains were constructed. These strains are applicable as recipient strains in future gene manipulation studies. As we know, this is the first genetic modification of this clinically relevant fungus.

Asexual sporulation (conidiogenesis) in filamentous fungi is a complex developmental process that requires precise coordination with primary metabolism and environmental stress responses. In the model fungus Aspergillus nidulans, we demonstrate that the bZIP-type transcription factor AtfA plays a central role in integrating conidiogenesis with the underlying metabolic and regulatory networks. Using combined ChIP-seq and RNA-seq analyses in wild-type, ∆atfA, and atfA-complemented strains under stress-free and oxidative stress (menadione) conditions, we identify a conserved AtfA binding motif and map its functional targets genome-wide. Our data reveal that AtfA binding to its target promoters is largely stress-independent, suggesting a preemptive regulatory mechanism in conidial development. AtfA directly binds to the promoters of genes involved in the MAPK signaling cascade, light-dependent sporulation, antioxidant defense, eisosome biogenesis, and the biosynthesis of trehalose and polyols—key metabolites supporting spore maturation and dormancy. Importantly, AtfA acts predominantly as a transcriptional activator, and its regulatory scope extends beyond stress adaptation to the orchestration of metabolic processes essential for spore integrity and germination. These findings position AtfA as a master integrator that synchronizes morphological development with metabolic preparedness during asexual reproduction in A. nidulans.