New method for rapid identification and quantification of fungal biomass using ergosterol autofluorescence

Epoxiconazole altered hepatic metabolism in adult zebrafish based on transcriptomic analysis

Epoxiconazole (EPX) is a triazole fungicide, which has been widely used in pest control of cereal crops. However, its extensive use has led to concerning levels of residue in water bodies, posing substantial risks to aquatic life. In this study, we characterized the toxicological effects of EPX on 6-month-old male and female zebrafish at 70 and 700 μg/L, respectively. The results revealed that EPX exposure markedly increased both body length and weight in zebrafish of both sexes, consequently elevating their condition factor. Besides, EPX exposure resulted in notable alterations in hepatic histopathology. These changes included loosened hepatocyte structure, ballooning degeneration, nucleolysis, and disappearance of cell line, with male zebrafish exhibiting more severe damage. High concentration of EPX also significantly increased hepatic lipid accumulation in male zebrafish, as well as increased hepatic triglyceride (TG) levels. Correspondingly, there was a notable alteration in the transcription of genes including cyp51, hmgcr, and PPAR-γ, which associated with cholesterol and lipid metabolism. Interestingly, with the hepatic transcriptomic analysis, high concentration of EPX produced 195 upregulated and 107 downregulated differential expression genes. Both KEGG and GO analyses identified significant enrichment of these genes in lipid and amino acid metabolism pathways. Notably, some key genes involved in the steroid synthesis pathway were marked upregulated. In addition, molecular docking study confirmed that EPX could bind CYP51 protein well (△G = -7.7 kcal/mol). Taken together, these findings demonstrated the multiple toxic effects of EPX on adult zebrafish.

From waste to protein: a new strategy of converting composted distilled grain wastes into animal feed

Distilled grain waste (DGW) is rich in nutrients and can be a potential resource as animal feed. However, DGW contains as much as 14% lignin, dramatically reducing the feeding value. White-rot fungi such as Pleurotus ostreatus could preferentially degrade lignin with high efficiency. However, lignin derivatives generated during alcohol distillation inhibit P. ostreatus growth. Thus, finding a new strategy to adjust the DGW properties to facilitate P. ostreatus growth is critical for animal feed preparation and DGW recycling. In this study, three dominant indigenous bacteria, including Sphingobacterium thermophilum X1, Pseudoxanthomonas byssovorax X3, and Bacillus velezensis 15F were chosen to generate single and compound microbial inoculums for DGW composting to prepare substrates for P. ostreatus growth. Compared with non-inoculated control or single microbial inoculation, all composite inoculations, especially the three-microbial compound, led to faster organic metabolism, shorter composting process, and improved physicochemical properties of DGW. P. ostreatus growth assays showed the fastest mycelial colonization (20.43 μg·g-1 ergosterol) and extension (9 mm/d), the highest ligninolytic enzyme activities (Lac, 152.68 U·g-1; Lip, 15.56 U·g-1; MnP, 0.34 U·g-1; Xylanase, 10.98 U·g-1; FPase, 0.71 U·g-1), and the highest lignin degradation ratio (30.77%) in the DGW sample after 12 h of composting with the three-microbial compound inoculation when compared to other groups. This sample was relatively abundant in bacteria playing critical roles in amino acid, carbohydrate, energy metabolism, and xenobiotic biodegradation, as suggested by metagenomic analysis. The feed value analysis revealed that P. ostreatus mycelia full colonization in composted DGW led to high fiber content retention and decreased lignin content (final ratio of 5% lignin) but elevated protein concentrations (about 130 g·kg-1 DM). An additional daily weight gain of 0.4 kg/d was shown in cattle feeding experiments by replacing 60% of regular feed with it. These findings demonstrate that compound inoculant consisting of three indigenous microorganisms is efficient to compost DGW and facilitate P. ostreatus growth. P. ostreatus decreased the lignin content of composted DGW during its mycelial growth, improving the quality of DGW for feeding cattle.

A Temporal Evolution Perspective of Lipase Production by Yarrowia lipolytica in Solid-State Fermentation

Lipases are enzymes that, in aqueous or non-aqueous media, act on water-insoluble substrates, mainly catalyzing reactions on carboxyl ester bonds, such as hydrolysis, aminolysis, and (trans)esterification. Yarrowia lipolytica is a non-conventional yeast known for secreting lipases and other bioproducts; therefore, it is of great interest in various industrial fields. The production of lipases can be carried on solid-state fermentation (SSF) that utilizes solid substrates in the absence, or near absence, of free water and presents minimal problems with microbial contamination due to the low water contents in the medium. Moreover, SSF offers high volumetric productivity, targets concentrated compounds, high substrate concentration tolerance, and has less wastewater generation. In this sense, the present work provides a temporal evolution perspective regarding the main aspects of lipase production in SSF by Y. lipolytica, focusing on the most relevant aspects and presenting the potential of such an approach.

A new look at edible and medicinal mushrooms as a source of ergosterol and ergosterol peroxide - UHPLC-MS/MS analysis

Ergosterol (ES) and ergosterol peroxide (EP) are secondary metabolites common for different mushrooms and responsible for health promoting effects, including anti-inflammatory, anticancer, antiviral activity, and reduction of the incidence of cardiovascular disease. In this study, a new method for determination of both ES and EP in mushroom extracts was developed. Two methods for UHPLC-MS/MS with the use of APCI and APPI sources were developed and compared. The UHPLC-APPI-MS/MS method was found to be more effective and convenient for the analysis of both compounds in 21 edible and 9 medicinal mushrooms. Among the investigated mushrooms, M. procera was found to contain the highest level of ES, while G. dryophilus constituted the richest source of EP. Therefore, it can be suggested that mushrooms are a valuable source of ES and EP in everyday human diet and can be used for development of nutraceuticals and functional food ingredients.

Cytochrome P450 Sterol 14 Alpha-Demethylase Gene SsCI72380 Is Required for Mating/Filamentation and Pathogenicity in Sporisorium scitamineum

Sugarcane smut is a significant sugarcane disease caused by Sporisorium scitamineum and is a large threat to the sugar industry in China and the world. Accordingly, it is important to study the pathogenic mechanism by which this disease occurs to identify effective prevention and control strategies. Gene SsCI72380, which encodes cytochrome P450 sterol 14 alpha-demethylase (CYP51), was screened out from the transcriptome of S. scitamineum. In this study, the functions of gene SsCI72380 were identified via the knockout mutants ΔSs72380⁺ and ΔSs72380⁻, which were obtained by polyethylene glycol (PEG)-mediated protoplast transformation technology, as well as the complementary mutants COM72380⁺ and COM72380⁻. The results showed that the CYP51 gene SsCI72380 played an important role in sporidial growth, sexual mating/filamentation, hyphae growth, and pathogenicity in S. scitamineum. Gene SsCI72380 may regulate the biosynthesis process of ergosterol by encoding CYP51 enzymes and then affecting the structure and function of the cell membrane. Gene SsCI72380 also played an important role in the response toward different abiotic stresses, including hyperosmotic stress, oxidative stress, and cell wall stress, by regulating the permeability of the cell membrane. In addition, gene SsCI72380 is a new type of pathogenic gene from S. scitamineum that enhances the pathogenicity of S. scitamineum.

Development of a consortium-based microbial agent beneficial to composting of distilled grain waste for Pleurotus ostreatus cultivation

BACKGROUND

Pleurotus ostreatus is an edible mushroom popularly cultivated worldwide. Distilled grain waste (DGW) is a potential substrate for P. ostreatus cultivation. However, components in DGW restrict P. ostreatus mycelial growth. Therefore, a cost-effective approach to facilitate rapid P. ostreatus colonization on DGW substrate will benefit P. ostreatus cultivation and DGW recycling.

RESULTS

Five dominant indigenous bacteria, Sphingobacterium sp. X1, Ureibacillus sp. X2, Pseudoxanthomonas sp. X3, Geobacillus sp. X4, and Aeribacillus sp. X5, were isolated from DGW and selected to develop a consortium-based microbial agent to compost DGW for P. ostreatus cultivation. Microbial agent inoculation led to faster carbohydrate metabolism, a higher temperature (73.2 vs. 71.2 °C), a longer thermophilic phase (5 vs. 3 days), and significant dynamic changes in microbial community composition and diversity in composts than those of the controls. Metagenomic analysis showed the enhanced microbial metabolisms, such as xenobiotic biodegradation and metabolism and terpenoid and polyketide metabolism, during the mesophilic phase after microbial agent inoculation, which may facilitate the fungal colonization on the substrate. In accordance with the bioinformatic analysis, a faster colonization of P. ostreatus was observed in the composts with microbial inoculation than in control after composting for 48 h, as indicated from substantially higher fungal ergosterol content, faster lignocellulose degradation, and higher lignocellulase activities in the former than in the latter. The final mushroom yield shared no significant difference between composts with microbial inoculation and control, with 0.67 ± 0.05 and 0.60 ± 0.04 kg fresh mushroom/kg DGW, respectively (p > 0.05).

CONCLUSION

The consortium-based microbial agent comprised indigenous microorganisms showing application potential in composting DGW for providing substrate for P. ostreatus cultivation and will provide an alternative to facilitate DGW recycling.

Autofluorescence Is a Common Trait in Different Oceanic Fungi

Natural autofluorescence is a widespread phenomenon observed in different types of tissues and organisms. Depending on the origin of the autofluorescence, its intensity can provide insights on the physiological state of an organism. Fungal autofluorescence has been reported in terrestrial and human-derived fungal samples. Yet, despite the recently reported ubiquitous presence and importance of marine fungi in the ocean, the autofluorescence of pelagic fungi has never been examined. Here, we investigated the existence and intensity of autofluorescence in five different pelagic fungal isolates. Preliminary experiments of fungal autofluorescence at different growth stages and nutrient conditions were conducted, reflecting contrasting physiological states of the fungi. In addition, we analysed the effect of natural autofluorescence on co-staining with DAPI. We found that all the marine pelagic fungi that were studied exhibited autofluorescence. The intensity of fungal autofluorescence changed depending on the species and the excitation wavelength used. Furthermore, fungal autofluorescence varied depending on the growth stage and on the concentration of available nutrients. Collectively, our results indicate that marine fungi can be auto-fluorescent, although its intensity depends on the species and growth condition. Hence, oceanic fungal autofluorescence should be considered in future studies when fungal samples are stained with fluorescent probes (i.e., fluorescence in situ hybridization) since this could lead to misinterpretation of results.