Colonization of solid particles by Rhizopus oligosporus and Aspergillus oryzae in solid-state fermentation involves two types of penetrative hyphae: A model-based study on how these hyphae grow

Host Material Viscoelasticity Determines Wrinkling of Fungal Films

Microbial organisms react to their environment and are able to change it through biological and physical processes. For example, fungi exhibit various growth morphologies depending on their host material. Here, we show how the rheological properties of the host material influence the fungal wrinkling morphology. Rheological data of the host material was set in relation to the growth morphology. On host material with high storage modulus, the fungal film was flat, whereas on host material with low storage modulus, the fungus showed a morphology made of folds and wrinkles. We combined our findings with mechanical instability theories and found that the formation of wrinkles and folds is dependent on the storage modulus of the host material. The connection between the wrinkling morphology and the storage modulus of the host material is shown with simple scaling theories. The amplitude, number of wrinkles, and wrinkle length follow geometrical laws, and the mechanical properties of the fungal film are expected to increase with increasing host material elasticity. The obtained results show the connection between living biological films, how they react to their surroundings, and the underlying physical mechanisms. They can provide a framework to further design fungal materials with specific surface morphologies.

A system approach to the modeling of fungal infections of the wheat leaf

Currently, studies on the mechanisms of the pathogenesis of plant diseases and their distribution in crops are intensively conducted in Russia and the world. First of all, this interest is associated with a significant effect of pathogens on the harvest. In Western Siberia, brown rust and powdery mildew are almost annually recorded in the crops of spring and winter wheat, reaching in some years up to the epiphytotic level. In this regard, methods for monitoring the condition of crops in order to predict their dynamics and plan agrotechnological events to control the state of plants in crops, including the development of fungal infection are developing. Models of fungal infections development on the wheat leaf (for example, brown rust) are used to monitor, predict and control the state of crops in order to optimize the growing process. Mathematical models allow computational experiments to make predictions about the risk dynamics of infections in different scenarios of global weather changes. Such designation of models assumes their hierarchical structure characteristic of multilevel modeling systems. This review presents models for the development of foliar fungal infections in crops, and formulates the methodological aspects of system modeling that can be used for adapting existing models and their units, and developing new models based on them. The article presents the structure of the hierarchical system for modeling the development of leafy infection, provides an overview of the units constituting the system, and discusses the issues of parametric adaptation of submodels. We demonstrated that, to date, plant growth and development models have been developed with varying degrees of detail. Currently, to develop a system for modeling the development of an infection in a crop, it is necessary to determine a large body of available experimental data and, by taking into account this data, we can put together a model as a system consisting of model modules, for which the models of basic processes have already been developed and described.

Influences of light on growth, reproduction and hypocrellin production by Shiraia sp. SUPER-H168

Light is a very important signal for fungi since it influences many different physiological responses. The effects of dark or light at different wavelengths on growth, reproduction and hypocrellins of Shiraia sp. SUPER-H168 were studied: dark, white, red, yellow, green, blue and purple. All incubations under different light conditions had significant stimulating effects on aerial hyphae and suppressing effects on hypocrellin biosynthesis compared with dark incubation. Under blue and purple light especially blue light, the colonies with profuse growth of aerial mycelium were formed. Hypocrellin production reached 13.73 mg per dish under dark condition, and decreased to 4.01 mg and 2.83 mg per dish under white and blue light, respectively. Light condition not only influenced hypocrellin production but also influenced the composition of hypocrellins. Four types of hyphae, namely surface, aerial, biofilm and penetrative hyphae, were observed by light microscopy and SEM. This study found that biofilm hyphae was so closely connected with production of secondary metabolites, and hypocrellins were only produced by biofilm hyphae. Light promoted sexual development and inhibited asexual reproduction, especially blue light strongly inhibited asexual development.