Combined Effect of Light and Nutrients on the Micromorphology of the White rot Fungus Cerrena Unicolor.

Light influences developmental pathways in fungi. Recent transcriptomic and biochemical analyses have demonstrated that light influences the metabolism of a white-rot basidiomycete Cerrena unicolor. However, the expression profile of genes involved in the growth and development, or micromorphological observations of the mycelium in response to variable lighting and culturing media, have not performed. We aim to reveal the effect of light and nutrients on C. unicolor growth and a potential relationship between the culture medium and lighting conditions on fungus micromorphological structures. Confocal laser scanning microscopy and scanning electron microscopy were employed for morphological observations of C. unicolor mycelium cultivated in red, blue, green, and white light and darkness on mineral and sawdust media. A comprehensive analysis of C. unicolor differentially expressed genes (DEGs) was employed to find global changes in the expression profiles of genes putatively involved in light-dependent morphogenesis. Both light and nutrients influenced C. unicolor growth and development. Considerable differences in the micromorphology of the mycelia were found, which were partially reflected in the functional groups of DEGs observed in the fungus transcriptomes. A complex cross-interaction of nutritional and environmental signals on C. unicolor growth and morphology was suggested. The results are a promising starting point for further investigations of fungus photobiology.

Bioprocess-Technological Potential of Irradiation-Based Fungal Pretreatment Platform Relevant to Lignocellulolytic Biocascade.

Lignocellulose-decaying fungal bioplatforms available are not commercially accessible and are limited to short-term use. In this study, those limitations were overcome by developing a platform using water-soaked rice straw (RS) biodegraded by irradiation-based fungal pretreatment (IBFP). This eco-friendly system increased the ability of RS to biodegrade and ferment without the generation of inhibitory compounds. When processed RS (i.e., with a water-soaking ratio of 81 % and irradiation dose of 80 kGy at 1 MeV and 0.12 mA) was pretreated with Dichomitus squalens for 9 days, the sugar yield was 58.5 % of the theoretical maximum. This sugar yield was comparable to that obtained with unirradiated RS for 15 days, which was 57.9 %. Furthermore, the ethanol concentration of 9.7 g L(-1) provided a yield of 58.1 %; the theoretical maximum and productivity at 0.40 g L(-1) h(-1) were determined after simultaneous saccharification and fermentation for 24 h. In addition, microscopic images revealed that IBFP induced predominant ultrastructural modifications to the surface of cell wall fibers. The peroxidative profiles for different biosystems were analyzed in order to understand substrate-specific biocascades based on the differences in biomass components. The activation level of core lignocellulolysis-related factors was analogous under the optimized conditions of each system.

Effects of weightlessness, space orientation and light on geotropism and the formation of fruit bodies in higher fungi.

The effect of flight factors on the growth and development of the fruit bodies of the higher fungus Polyporus brumalis is investigated under the conditions of an experiment on the earth satellite Cosmos 690. Fungi were grown on the earth under conditions of simulated flight and transit; fungi were also grown in the laboratory at a temperature similar to that in flight, at various orientations and under various illuminations. Polyporus brumalis grows well on wort; it forms fruit bodies on long pedicles (up to 25 cm) and possesses a strongly marked negative geotropism. Investigations have shown that the formation of hymenium and pileus is induced by definite time exposures to light. In darkness the formation of fruit bodies takes place, but without formation of hymenium and pileus, and the rate of growth is greater than in light. The strong negative geotropism remains in fruit bodies when developed in darkness and with test-tubes in a vertical position. When the test-tube orientation is changed the pedicles change direction in darkness as well as in light. In maintaining their negative geotropism the fruit bodies bend with changes of space orientation. In the absence of gravity a disorientation of fruit bodies takes place, and the pedicles are strongly twisted into a spiral or into a ball. A flattened type of fruit body can also occur. Such a picture of growth and formation was not observed in control samples. Thus, there is a strong dependence of the formation of the fruit body of Polyporus brumalis on space orientation, gravity and light.