Conidia of Aspergillus niger are produced on conidiophores. Here, maturation of conidia on these asexual reproductive structures was studied. Pigmented conidia that had developed on conidiophores for 2, 5, and 8days were similarly resistant to heat and were metabolically active as shown by CO release and conversion of the metabolic probe Tempone. A total number of 645-2421 genes showed a ⩾2-fold change in expression when 2-day-old conidia were compared to 5- and 8-day-old spores. Melanin was extracted more easily from the cell wall of 2-day-old conidia when compared to the older spores. In addition, mannitol content and germination rate of the 2-day-old conidia were higher. Dispersal efficiency by water was lower in the case of the 8-day-old conidia but no differences were observed in dispersal by wind and a hydrophobic moving object. These data and the fact that only a minor fraction of the conidia on a conidiophore were dispersed in the assays imply that a single colony of A. niger releases a heterogeneous population of conidia. This heterogeneity would provide a selective advantage in environments with rapidly changing conditions such as availability of water.

A fungal colony maintains its integrity via flow of cytoplasm along mycelium network. This flow, together with possible coordination of mycelium tips propagation, is controlled by calcium waves and associated waves of electrical potential changes. We propose that these excitation waves can be employed to implement a computation in the mycelium networks. We use FitzHugh-Nagumo model to imitate propagation of excitation in a single colony of Aspergillus niger. Boolean values are encoded by spikes of extracellular potential. We represent binary inputs by electrical impulses on a pair of selected electrodes and we record responses of the colony from sixteen electrodes. We derive sets of two-inputs-on-output logical gates implementable the fungal colony and analyse distributions of the gates.

Solid‐state NMR (ssNMR) spectroscopy facilitates the non‐destructive characterization of structurally heterogeneous biomolecules in their native setting, for example, comprising proteins, lipids and polysaccharides. Here we demonstrate the utility of high and ultra‐high field 1H‐detected fast MAS ssNMR spectroscopy, which exhibits increased sensitivity and spectral resolution, to further elucidate the atomic‐level composition and structural arrangement of the cell wall of Schizophyllum commune, a mushroom‐forming fungus from the Basidiomycota phylum. These advancements allowed us to reveal that Cu(II) ions and the antifungal peptide Cathelicidin‐2 mainly bind to cell wall proteins at low concentrations while glucans are targeted at high metal ion concentrations. In addition, our data suggest the presence of polysaccharides containing N‐acetyl galactosamine (GalNAc) and proteins, including the hydrophobin proteins SC3, shedding more light on the molecular make‐up of cells wall as well as the positioning of the polypeptide layer. Obtaining such information may be of critical relevance for future research into fungi in material science and biomedical contexts.

Hyphae of higher fungi grow at their tips and are compartmentalized by porous septa that enable inter-compartmental cytoplasmic streaming. Woronin bodies discontinue cytoplasmic streaming by plugging the septal pores. Here, it was assessed whether apical compartments of Aspergillus niger sustain their own growth or whether their growth depends on subapical compartments. Hyphae of wildtype and the ΔhexA strain, lacking Woronin bodies, had a similar morphology and growth rate. A total of 58% and 17% of the hyphae continued growing, respectively, after dissecting the 2nd compartment. Extension rate of the apical compartments that continued growing was not affected, even when the carbon or nitrogen source was limiting. Thus, apical compartments are self-sustaining in growth. It was also shown that the first 8 subapical compartments of the wildtype, but not of the ΔhexA strain, function as a backup system for growth by forming new branches when their apical neighbouring compartment has been damaged. This backup system is pivotal in nature because of the life style of fungi to continuously explore their surrounding substrate that may prove hostile.

Wood-degrading fungi in the phylum Basidiomycota play a crucial role in nutrient recycling by breaking down all components of wood. Fungi have evolved transcriptional networks that regulate expression of wood-degrading enzymes, allowing them to prioritize one nutrient source over another.

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Hyphae at the outer part of colonies of Aspergillus niger and Aspergillus oryzae are heterogeneous with respect to transcriptional and translational activity. This heterogeneity is maintained by Woronin body mediated closure of septal pores that block interhyphal mixing of cytoplasm. Indeed, heterogeneity between hyphae is abolished in ΔhexA strains that lack Woronin bodies. The subpopulation of hyphae with high transcriptional and translational activity secretes enzymes that degrade the substrate resulting in breakdown products that serve as nutrients. The role of hyphae with low transcriptional and translational activity was not yet known. Here, we show that this subpopulation is more resistant to environmental stress in A. oryzae, in particular to temperature stress, when compared to hyphae with high transcriptional and translational activity. Notably, all hyphae of the ΔhexA strain of A. oryzae were sensitive to heat stress explained by the reduced heterogeneity in this strain. Together, we show that different subpopulations of hypha secrete proteins and resist heat stress showing the complexity of a fungal mycelium.

Aspergillus niger is used by the industry to produce enzymes and metabolites such as citric acid. in liquid cultures, it can grow as a dispersed mycelium or as micro-colonies with a width in the micrometer to millimeter range. Here, it was assessed whether expression of genes encoding secreted enzymes depends on mycelium morphology. to this end, expression of the reporter gene gfp from the promoters of the glucoamylase gene glaA, the feruloyl esterase gene faeA and the α-glucuronidase gene aguA was causally related to micro-colony size within a liquid shaken culture. Data could be fitted by hyperbolic functions, implying that the genes encoding these secreted proteins are expressed in a shell at the periphery of the micro-colony. The presence of such a shell was confirmed by confocal microscopy. Modelling predicted that the width of these zones was 13 to 156 µm depending on growth medium and micro-colony diameter. together, data indicate that the highest productive micro-colonies are those colonies that have a radius ≤ the width of the peripheral expression zone.Filamentous fungi form mycelia that consist of a network of hyphae that grow at their tips and that branch sub-apically. Mycelia of aspergilli can reach a diameter in the sub-millimeter scale (micro-colonies) to centimeter scale (macro-colonies) depending on the size and the composition of the solid substrate 1 . For instance, Aspergillus forms micro-colonies on wheat kernels, whereas macro-colonies can be formed on fruits or bulbs of plants. In liquid shaken cultures, mycelium of Aspergillus grows dispersed, as micro-colonies, or in an intermediate state called clumps 1 . Dispersed mycelium consists of small networks of hyphae, while micro-colonies, also known as pellets, consist of a clear central and outer zone 2 . Notably, micro-colonies of Aspergillus niger produce more citric acid when compared to dispersed mycelium 3,4 . Why micro-colonies are more productive is not yet clear. It may be caused by the effect of the fungal morphology on the viscosity of the medium being high and low during dispersed growth and growth as micro-colonies, respectively 5 . At the same time, availability of oxygen and nutrients may impact productivity. Diffusion of these compounds would be sufficient in the case of dispersed mycelium while it would be limiting in the center of micro-colonies 6 .So far, it is not known whether morphology of the mycelium affects production of secreted proteins. It was shown that micro-colonies within a liquid shaken culture are heterogeneous with respect to size and gene expression 2 . However, the relation between colony size and expression of genes encoding genes was not assessed. Therefore, we here studied whether micro-colony diameter affects expression of genes encoding secreted proteins in A. niger. To this end, the highly expressed genes encoding feruloyl esterase FaeA 7,8 , α-glucuronidase AguA 7,9 and glucoamylase GlaA 7,10 were used as model genes of xylanolytic (FaeA, AguA) and amylolytic (GlaA) activity. Data show that these gen...