The fungal sexual revolution continues: discovery of sexual development in members of the genus Aspergillus and its consequences

Simultaneous saccharification and citric acid production from paper wastewater pretreated banana pseudostem: Optimization of fermentation medium formulation and kinetic assessment

This study optimized the simultaneous saccharification and citric acid (CA) production from banana pseudostem (BP). Thereafter, kinetic assessment of Aspergillus brasiliensis growth and CA production were determined for the optimum conditions using fresh water (SSF_optimizedFW) or dairy wastewater (SSF_DWW) and compared to Sabouraud Dextrose Emmon's medium modified with BP (SSF_SDEmodified). The optimized conditions gave a CA concentration of 14.408 g/L. Kinetic assessment revealed the same maximum specific growth rates (μ_max) (0.05 h^-1) for all three bioprocesses, while the SSF_SDEmodified process resulted in the highest maximum potential CA concentration (P_m) (13.991 g/L) in comparison to the SSF_DWW (P_m = 13.095 g/L) and SSF_optimizedFW (P_m = 12.967 g/L) systems. Findings from this study facilitates the implementation of waste-based lignocellulosic bioprocesses that may eradicate the use of expensive pretreatment chemicals, fermentation medium constituents, and resources, in keeping with the water, energy and food nexus towards developing a circular bioeconomy.

Novel Treatment Approach for Aspergilloses by Targeting Germination

Germination of conidia is an essential process within the Aspergillus life cycle and plays a major role during the infection of hosts. Conidia are able to avoid detection by the majority of leukocytes when dormant. Germination can cause severe health problems, specifically in immunocompromised people. Aspergillosis is most often caused by Aspergillus fumigatus (A. fumigatus) and affects neutropenic patients, as well as people with cystic fibrosis (CF). These patients are often unable to effectively detect and clear the conidia or hyphae and can develop chronic non-invasive and/or invasive infections or allergic inflammatory responses. Current treatments with (tri)azoles can be very effective to combat a variety of fungal infections. However, resistance against current azoles has emerged and has been increasing since 1998. As a consequence, patients infected with resistant A. fumigatus have a reported mortality rate of 88% to 100%. Especially with the growing number of patients that harbor azole-resistant Aspergilli, novel antifungals could provide an alternative. Aspergilloses differ in defining characteristics, but germination of conidia is one of the few common denominators. By specifically targeting conidial germination with novel antifungals, early intervention might be possible. In this review, we propose several morphotypes to disrupt conidial germination, as well as potential targets. Hopefully, new antifungals against such targets could contribute to disturbing the ability of Aspergilli to germinate and grow, resulting in a decreased fungal burden on patients.

Sclerotia formed by citric acid producing strains of Aspergillus niger: Induction and morphological analysis

Some strains of Aspergillus niger have been previously reported to produce sclerotia under certain conditions. Sclerotia are aggregations of hyphae which can act either as survival or as sexual structures in species related to A. niger. In this study, we were able to induce the formation of sclerotia in the progenitor of the industrial citric acid producing strains of A. niger, ATCC 1015, and in pyrG mutants derived from it. Sclerotia can be stably formed by ATCC 1015 on malt extract agar medium supplemented with raisins, showing a spatial differentiation of the fungus dependent on the addition and on the position of the fruits into the medium. On other media, including malt extract agar, pyrG auxotrophs also form abundant sclerotia, while the complementation of this gene reverses this phenotype. Additionally, a macro- and microscopical analysis of the sclerotia is reported. Our results show that the sclerotia formed by A. niger are similar to those formed by other fungi, not only in their morphology but also in their ability to germinate and regenerate the organism.