Fungal biology最新文献

Polycyclic aromatic hydrocarbons (PAHs) are widely present in the environment, causing increasing concern because of their impact on soil health, food safety and potential health risks. Four bioremediation strategies were examined to assess the dissipation of PAHs in agricultural soil amended with sewage sludge over a period of 120 days: soil-sludge natural attenuation (SS); phytoremediation using maize (Zea mays L.) (PSS); mycoremediation (MR) separately using three white-rot fungi (Pleurotus ostreatus, Phanerochaete chrysosporium and Irpex lacteus); and plant-assisted mycoremediation (PMR) using a combination of maize and fungi. In the time frame of the experiment, mycoremediation using P. chrysosporium (MR-PH) exhibited a significantly higher (P < 0.05) degradation of total PAHs compared to the SS and PSS treatments, achieving a degradation rate of 52 %. Both the SS and PSS treatments demonstrated a lower degradation rate of total PAHs, with removal rates of 18 % and 32 %, respectively. The PMR treatments showed the highest removal rates of total PAHs at the end of the study, with degradation rates of 48–60 %. In the shoots of maize, only low- and medium-molecular-weight PAHs were found in both the PSS and PMR treatments. The calculated translocation and bioconversion factors always showed values < 1. The analysed enzymatic activities were higher in the PMR treatments compared to other treatments, which can be positively related to the higher degradation of PAHs in the soil.

Microsclerotia (MS) are considered one of the most promising propagules for use as active ingredients in biopesticides due to their tolerance to abiotic factors and ability to produce infective conidia for the control of pests. Therefore, the objective of this research was to establish the conditions required to induce the formation of microsclerotia in Metarhizium robertsii Mt004 and to study its development process, tolerance to abiotic factors and insecticidal activity of MS-derived conidia. M. robertsii started to form hyphal aggregates after 2 days and looked more compact after 8 days. MS were mature and pigmented after 20 days. The final yield was 2.0 × 10³ MS/mL and MS size varied between 356.9 and 1348.4 μm. Ultrastructure analysis revealed that mature MS contained only a few live cells embedded in an extracellular matrix. Mature MS were more tolerance to UV-B radiation, heat and storage trials than conidia from Solid State Fermentation. MS-derived conidia were as virulent as conidia against Diatraea saccharalis larvae. These results showed that MS are promising propagules for the development of more persistent and efficient biopesticides for harsh environmental conditions. Our findings provide a baseline for production and a better understanding of microsclerotia development in M. robertsii strains.

Although tyrosol is a quorum-sensing molecule of Candida species, it has antifungal activity at supraphysiological concentrations. Here, we studied the effect of tyrosol on the physiology and genome-wide transcription of Aspergillus nidulans to gain insight into the background of the antifungal activity of this compound. Tyrosol efficiently reduced germination of conidia and the growth on various carbon sources at a concentration of 35 mM. The growth inhibition was fungistatic rather than fungicide on glucose and was accompanied with downregulation of 2199 genes related to e.g. mitotic cell cycle, glycolysis, nitrate and sulphate assimilation, chitin biosynthesis, and upregulation of 2250 genes involved in e.g. lipid catabolism, amino acid degradation and lactose utilization. Tyrosol treatment also upregulated genes encoding glutathione-S-transferases (GSTs), increased specific GST activities and the glutathione (GSH) content of the cells, suggesting that A. nidulans can detoxify tyrosol in a GSH-dependent manner even though this process was weak. Tyrosol did not induce oxidative stress in this species, but upregulated “response to nutrient levels”, “regulation of nitrogen utilization”, “carbon catabolite activation of transcription” and “autophagy” genes. Tyrosol may have disturbed the regulation and orchestration of cellular metabolism, leading to impaired use of nutrients, which resulted in growth reduction.

Xylitol is an increasingly popular functional food additive, and the newly isolated yeast Wickerhamomyces anomalus WA has shown extensive substrate utilization capability, with the ability to grow on hexose (d-galactose, d-glucose, d-mannose, l-fructose, and d-sorbose) and pentose (d-xylose and l-arabinose) substrates, as well as high tolerance to xylose at concentrations of up to 300 g/L. Optimal xylitol fermentation conditions were achieved at 32 °C, 140 rpm, pH 5.0, and initial cell concentration OD₆₀₀ of 2.0, with YP (yeast extract 10 g/L, peptone 20 g/L) as the optimal nitrogen source. Xylitol yield increased from 0.61 g/g to 0.91 g/g with an increase in initial substrate concentration from 20 g/L to 180 g/L. Additionally, 20 g/L glycerol was found to be the optimal co-substrate for xylitol fermentation, resulting in an increase in xylitol yield from 0.82 g/g to 0.94 g/g at 140 rpm, enabling complete conversion of xylose to xylitol.

Thermotolerance has been viewed as an uncommon characteristic among the fungi and one of the reasons that less than 1% of the described species operate as opportunistic pathogens of humans. Growth at 37°C is certainly a requirement for a fungus that invades the body core, but tens of thousands of nonpathogenic species are also able to grow at this temperature. Ergo, body temperature does not serve as a thermal barrier to the development of infections by many harmless fungi. The absence of other virulence factors must be more demanding. This observation raises questions about the hypothetical links between climate change and the increasing number of life-threatening human mycoses. Given the widespread distribution of fungal thermotolerance and the 1°C (2°F) increase in global temperature over the last 140 years it seems unlikely that the warming climate has driven the evolution of more virulent strains of fungi. More compelling explanations for the changes in the behavior of fungi as disease agents include their adaptation to the widening use of azole antifungals in hospitals and the wholesale application of millions of tons of the same class of heterocyclic chemicals in agriculture. On the other hand, climate change is having a significant effect on the spread of human mycoses by extending the geographical range of pathogenic fungi. A related increase in fungal asthma caused by spore inhalation is another likely consequence of planetary change.

Auricularia cornea is an important edible mushroom crop in China but the occurrence of cobweb disease has cause significance economic loss in its production. The rate of disease occurrence is 16.65% all over the country. In the present study, a new pathogen Hypomyces cornea sp. nov. was found to cause the cobweb disease. In July 2021, three strains of fungal pathogen were isolated from infected fruiting bodies and identified as H. cornea based on morphological studies and molecular phylogenetic analysis of internal transcribed spacer (ITS) of nuclear ribosomal DNA, mitochondrial large subunit (LSU) of rRNA and the partial translation elongation factor 1-alpha genes. The representative isolates of the pathogenic Hypomyces species used to perform pathogenicity test with spore suspension that caused similar symptoms as those observed in the cultivated field, and same pathogens could be re-isolated, which fulfill Koch's postulates. The typical biological characterization was examined of the serious pathogen to determine its favorable growth conditions, including suitable temperature, pH, carbon, nitrogen sources and light conditions. The findings revealed an optimum temperature of 25 °C, pH of 6, and soluble starch and peptone as the preferred carbon and nitrogen sources, respectively. The hyphal growth inhibition method was used for primary in vitro screening test of seven common fungicides, and the most suitable fungicide is Prochloraz manganese chloride complex, the EC₅₀ values of cobweb pathogen and mushrooms were 0.085 μg/mL and 2.452 μg/mL, respectively. The results of our research provide an evidence-based basis for the effective prevention and treatment of A. cornea cobweb disease.