Ergosterol Content Research Articles

Mechanistic Insights into Cellular and Molecular Targets of Zinc Oxide Quantum Dots (ZnO QDs) in Fungal Pathogen, Candida albicans: One Drug Multi-Targeted Therapeutic Approach.

Rationally designed multitargeted drugs, known as network therapeutics/multimodal drugs, have emerged as versatile therapeutic solutions to combat drug-resistant microbes. Here, we report novel mechanistic insights into cellular and molecular targets of ZnO quantum dots (QDs) against Candida albicans, a representative of fungal pathogens. Stable, monodispersed 4-6 nm ZnO QDs were synthesized using a wet chemical route, which exhibited dose-dependent inhibition on the growth dynamics of Candida. Treatment with 200 μg/mL ZnO QDs revealed an aberrant morphology and a disrupted cellular ultrastructure in electron microscopy and led to a 23% reduction in ergosterol content and a 53% increase in intracellular reactive oxygen species. Significant increase in steady-state fluorescence polarization and fluorescence lifetime decay of membrane probe 1,6-diphenyl-1,3,5-hexatriene (DPH) in treated cells, respectively, implied reduction in membrane fluidity and enhanced microviscosity. The observed reduction in passive diffusion of fluorescent Rhodamine 6G across the membrane validated the intricate relationship between ergosterol, membrane fluidity, and microviscosity. An inverse relationship existing between ergosterol biosynthetic genes, ERG11 and ERG3 in treated cells, related well with displayed higher susceptibilities. Furthermore, treated cells exhibited impaired functionality and downregulation of ABC drug efflux pumps. Multiple cellular targets of ZnO QDs in Candida were validated by in silico molecular docking. Thus, targeting ERG11, ERG3, and ABC drug efflux pumps might emerge as a versatile, nano-ZnO-based strategy in fungal therapeutics to address the challenges of drug resistance.

Phenotypic and Genotypic Characterization of Candida parapsilosis complex isolates from a Lebanese Hospital.

The opportunistic fungal pathogen Candida parapsilosis is a major causative agent of candidiasis leading to death in immunocompromised individuals. Azoles are the first line of defense in treatment by inhibiting ERG11, involved in the synthesis of ergosterol, the main sterol fungal sterol. Resistance to azoles is on the increase worldwide including in Lebanon. The purpose of this study is to characterize nine hospital isolates labeled as C. parapsilosis: four resistant and five sensitive to fluconazole. Phenotypic characterization was achieved through a battery of tests that target pathogenicity attributes such as virulence, biofilm formation, stress resistance, and ergosterol content. Genotypic analysis was done through whole genome sequencing to mutations in key virulence and resistance genes. Phylogenetic comparison was performed to determine strain relatedness and clonality. Genomic data and phylogenetic analysis revealed that three of the nine C. parapsilosis isolates were misidentified; two as C. orthopsilosis and C. metapsilosis belonging to the C. parapsilosis complex, while the third was C. albicans. Moreover, several known and novel mutations in key drug resistance and virulence genes were identified such as ERG11, ERG3, ERG6, CDR1, and FAS2. Phylogenetic analysis revealed a high degree of relatedness and clonality within our C. parapsilosis isolates. Our results showed that resistant isolates had no increased ergosterol content, no statistically significant difference in virulence, but exhibited an increase in biofilm content compared to the sensitive isolates. In conclusion, our study, the first of its kind in Lebanon, suggests several mechanisms of antifungal drug resistance in C. parapsilosis hospital isolates.

Design, Synthesis, and 3D-QASR of 2-Ar-1,2,3-triazole Derivatives Containing Hydrazide as Potential Fungicides.

A series of novel 2-Ar-1,2,3-triazole derivatives were designed and synthesized based on our previously discovered active compound 6d against Rhizoctonia solani. Most of these compounds exhibited good antifungal activity against R. solani at a concentration of 25 μg/mL. Based on the results of biological activity, we established a three-dimensional quantitative structure-activity relationship (3D-QSAR) model that guided the synthesis of compound 7y. Compound 7y exhibited superior activity against R. solani (EC50 = 0.47 μg/mL) compared to the positive controls hymexazol (EC50 = 12.80 μg/mL) and tebuconazole (EC50 = 0.87 μg/mL). Furthermore, compound 7y demonstrated better protective activity than the aforementioned two commercial fungicides in both detached leaf assays and greenhouse experiments, achieving 56.21% and 65.75% protective efficacy, respectively, at a concentration of 100 μg/mL. The ergosterol content was determined and molecular docking was performed to explore the mechanism of these active molecules. DFT calculation and MEP analysis were performed to illustrate the results of this study. These results suggest that compound 7y could serve as a novel 2-Ar-1,2,3-triazole lead compound for controlling R. solani.

Transcriptome Analysis Reveals Potential Regulators of DMI Fungicide Resistance in the Citrus Postharvest Pathogen Penicillium digitatum.

Green mold, caused by Penicillium digitatum, is the major cause of citrus postharvest decay. Currently, the application of sterol demethylation inhibitor (DMI) fungicide is one of the main control measures to prevent green mold. However, the fungicide-resistance problem in the pathogen P. digitatum is growing. The regulatory mechanism of DMI fungicide resistance in P. digitatum is poorly understood. Here, we first performed transcriptomic analysis of the P. digitatum strain Pdw03 treated with imazalil (IMZ) for 2 and 12 h. A total of 1338 genes were up-regulated and 1635 were down-regulated under IMZ treatment for 2 h compared to control while 1700 were up-regulated and 1661 down-regulated under IMZ treatment for 12 h. The expression of about half of the genes in the ergosterol biosynthesis pathway was affected during IMZ stress. Further analysis identified that 84 of 320 transcription factors (TFs) were differentially expressed at both conditions, making them potential regulators in DMI resistance. To confirm their roles, three differentially expressed TFs were selected to generate disruption mutants using the CRISPR/Cas9 technology. The results showed that two of them had no response to IMZ stress while ∆PdflbC was more sensitive compared with the wild type. However, disruption of PdflbC did not affect the ergosterol content. The defect in IMZ sensitivity of ∆PdflbC was restored by genetic complementation of the mutant with a functional copy of PdflbC. Taken together, our results offer a rich source of information to identify novel regulators in DMI resistance.

Impact of drying methods on ergosterol content and cholesterol-lowering activity of Ganodermalucidum

The development of the food industry is an integral part of the development of our world. In recent years, there has been a growing interest in food as drugs. Basidiomycetes grown in submerged culture have the potential to be used as food supplements for a healthy diet. This study investigated the ergosterol content of Ganoderma lucidum obtained in submerged culture and dried using different techniques to identify the prospects for food additive applications. Specifically, the ergosterol content was higher in samples dried by freezing or oven-dried at low temperatures than in air or oven-dried at high temperatures. In addition, the study performed chemoinformatic calculations to determine the binding energy of ergosterol and cholesterol to the NPC1 receptor, which is a cholesterol transporter in humans. The results showed that ergosterol had a better binding energy (−9.2 kcal/mol) than cholesterol (−8.4 kcal/mol). This suggests that basidiomycete may have potential as a food additive or drug due to its ability to bind more efficiently to the NPC1 receptor. This research emphasizes the importance of developing technology to produce food additives from natural components, considering their biological value. Therefore, the research indicates that Ganoderma lucidum may be a dietary supplement to lower human cholesterol levels.

Sequential Induction of Drug Resistance and Characterization of an Initial Candida albicans Drug-Sensitive Isolate.

The pathogenic fungus Candida albicans is a leading agent of death in immunocompromised individuals with a growing trend of antifungal resistance. The purpose is to induce resistance to drugs in a sensitive C. albicans strain followed by whole-genome sequencing to determine mechanisms of resistance. Strains will be assayed for pathogenicity attributes such as ergosterol and chitin content, growth rate, virulence, and biofilm formation. We observed sequential increases in ergosterol and chitin content in fluconazole-resistant isolates by 78% and 44%. Surface thickening prevents the entry of the drug, resulting in resistance. Resistance imposed a fitness trade-off that led to reduced growth rates, biofilm formation, and virulence in our isolates. Sequencing revealed mutations in genes involved in resistance and pathogenicity such as ERG11, CHS3, GSC2, CDR2, CRZ2, and MSH2. We observed an increase in the number of mutations in key genes with a sequential increase in drug-selective pressures as the organism increased its odds of adapting to inhospitable environments. In ALS4, we observed two mutations in the susceptible strain and five mutations in the resistant strain. This is the first study to induce resistance followed by genotypic and phenotypic analysis of isolates to determine mechanisms of drug resistance.

Overexpression of PDR16 Confers Amphotericin B Resistance in a PMP3-Dependent Manner in Yeast Saccharomyces cerevisiae.

Invasive fungal infections in humans with compromised immune systems are the primary cause of morbidity and mortality, which is becoming more widely acknowledged. Amphotericin B (AmB) is one of the antifungal drugs used to treat such infections. AmB binds with plasma membrane ergosterol, inducing cellular ions to leak and causing cell death. Reduction in ergosterol content and modification of cell walls have been described as AmB resistance mechanisms. In addition, when the sphingolipid level is decreased, the cell becomes more susceptible to AmB. Previously, PDR16, a gene that encodes phosphatidylinositol transfer protein in Saccharomyces cerevisiae, was shown to enhance AmB resistance upon overexpression. However, the mechanism of PDR16-mediated AmB resistance is not clear. Here, in this study, it was discovered that a plasma membrane proteolipid 3 protein encoded by PMP3 is essential for PDR16-mediated AmB resistance. PDR16-mediated AmB resistance does not depend on ergosterol, but a functional sphingolipid biosynthetic pathway is required. Additionally, PMP3-mediated alteration in membrane integrity abolishes PDR16 mediated AmB resistance, confirming the importance of PMP3 in the PDR16 mediated AmB resistance.

Evaluation of sterols as markers of fungal spoilage in red pepper powder

Red pepper powder (RPP) made from ground dried red pepper (Capsicum annuum L.) is prone to adulteration with fungal-spoiled RPP to gain unfair profits in Korea. This study aimed to investigate the effects of fungal infection on the ergosterol and phytosterol content of RPP and evaluate the potential of the sterol content as a marker for identifying fungal-spoiled RPP. Ergosterol was detected only in fungal-spoiled RPP and not in unspoiled RPP [<LOD (2.3 mg/kg)], making it a reliable marker for fungal spoilage. The ergosterol content [<LOQ (7.07 mg/kg)–87.4 mg/kg] in commercial RPP samples suggested contamination levels of 0.2–28.9 w/w% by fungal-spoiled RPP, depending on the fungal species. Despite elevated levels of campesterol, stigmasterol, and β-sitosterol and high stigmasterol-to-β-sitosterol ratios in fungal-spoiled RPP compared to unspoiled RPP, these parameters were not reliable markers due to natural variations of these compounds in RPP, not specific to fungal influence.

Inhibitory effects of Lactobacillus brevis on Aspergillus westerdijkiae and antifungal compounds identification

Ochratoxin A (OTA), a secondary metabolite produced by Aspergillus and Penicillium, seriously contaminates grapes and its products. Inhibiting the growth of OTA-producing fungi is the best approach to reduce OTA contamination in grapes. This study was to reveal the inhibition mechanism of Lactobacillus brevis 8–2B on Aspergillus westerdijkiae. Research has found that L. brevis 8–2B could inhibit the germination, growth, and OTA synthesis of A. westerdijkiae. The antifungal activity of L. brevis 8–2B is attributed to the synergistic effect of acetic acid, lactic acid, citric acid, longifolene, methyl salicylate, 3-phenyl-2-propenal, nystatin, and itraconazole. The inhibitory effect of L. brevis 8–2B on A. westerdijkiae was the synergistic effect of these active substances. Ultrastructure observation and flow cytometry results showed that the mycelia structure, cell membrane and cell wall of A. westerdijkiae were disrupted, the cells showed apoptosis, and the ergosterol content in the cells was reduced. Transcriptome analysis revealed that the expression levels of ribosomal biosynthesis genes and cell wall chitin synthesis genes in inhibited A. westerdijkiae were up-regulated, while the expression of chitin degrading enzyme genes was down-regulated to enhance its primary growth and development. In addition, L. brevis 8–2B also inhibits the expression of amino acid synthesis and glycolysis genes in A. westerdijkiae, reducing the generation of secondary metabolite precursors such as NRPS and PKS, thereby inhibiting OTA biosynthesis. On grapes, L. brevis 8–2B could inhibit the infection of A. westerdijkiae, and prolong its shelf life. This study provides new insights for the research and development of novel agent to control OTA contamination.

Investigating safe storage conditions to mitigate aflatoxin contamination in rice

Mold contamination, especially with aflatoxin-producing Aspergillus species, poses a notable issue for rice, particularly in ready-to-eat (RTE) items, turning them inedible for both humans and animals due to the possible presence of aflatoxins (AFs). Understanding accumulation of the molds and their resulting toxic metabolites is critical in designing quality control strategies in the production of RTE rice-based products such as germinated instant rice, extruded rice cakes and crispies, rice-derived malted beer and flour. There is no clear understanding of the growth of A. flavus and AF accumulation on various fractions of hybrid rice cultivars utilized in the manufacture of the RTE rice-derived food products. In the present work, different experiments were conducted to identify the extent to which temperature (20°C, 25°C, and 30°C), relative humidity (RH) (75%, 85%, and 95%), storage period, storage moisture content (MC), and initial spore concentration impacted the growth of AF-producing A. flavus NRRL 3357. The study also examined how these factors affected ergosterol content and aflatoxin B1 (AFB1) production in different hybrid rice fractions including rough, brown, and milled rice, at different MCs (12%, 15%, and 18% w.b.). The samples, both autoclaved and non-autoclaved rice fractions, were inoculated with different A. flavus spore concentrations (1 × 104 and 1 × 106 spores/mL) and incubated at different temperatures and RHs. A. flavus plate count, ergosterol and AFB1 production were measured over time for up to 60 days. The maximum A. flavus growth was observed in brown rice (autoclaved) at 30°C and 95% RH. Brown rice fraction (non-autoclaved) had the highest AFB1 concentration (9.20 μg/g) which was determined after 15 days of incubation at 30°C and 75% RH. Aflatoxin B1 concentration in brown rice (non-autoclaved) fraction inoculated with the highest concentration of A. flavus and stored at 30°C and 95% RH initially increased after 20 days and then decreased towards the end of the storage period. The findings from this research provide important data related to the growth behavior of A. flavus on various rice fractions. The results contribute to understanding of the safety of RTE foods derived from various fractions of rice that is utilized by the food industry.

Functional study of two ER localized sterol C-14 reductases in Aspergillus oryzae.

Ergosterol is an important component of fungal cell membrane. Ergosterol biosynthesis involves sterol C-14 reductase, a key enzyme in ergosterol biosynthesis, which has been well studied in Saccharomyces cerevisiae. However, little studies about this important enzyme in Aspergillus oryzae. In this study, two sterol C-14 reductases named AoErg24A and AoErg24B were identified in A. oryzae using bioinformatics analysis. Through phylogenetic tree, expression pattern, subcellular localization, and yeast functional complementation analyses, we discovered that both AoErg24A and AoErg24B are conserved and localized to the endoplasmic reticulum (ER). Both enzymes can partially restore the temperature sensitivity phenotype of a S. cerevisiae erg24 weak mutant. Overexpression of AoErg24A in A. oryzae increased 1.6 times of ergosterol content, while overexpression of AoErg24B led to a slight decrease of ergosterol. Both genes affect the sporulation of A. oryzae. These results uncovered that the two genes function differently in ergosterol biosynthesis. Thus, this study further enhances our understanding of ergosterol biosynthesis in A. oryzae and lays a good foundation for A. oryzae to be used in industrial ergosterol production.

Aspergillus fumigatus ctf1–a novel zinc finger transcription factor involved in azole resistance

ABSTRACT Elucidating the mechanisms underlying antifungal resistance in Aspergillus fumigatus, discovering new antifungal targets, and developing drugs to inhibit resistance are the key approaches to treating A. fumigatus infections. Here, we investigated the function of ctf1 (AFUA_1G03800), a gene encoding a C6 transcription factor. Homologous recombination replacement technology was employed to construct ctf1-knockout and revertant strains. Fungal morphological observations revealed that the growth of the knockout strain was slower, showing fewer conidia. The minimum inhibitory concentration of triazoles was determined by performing the E-test and by using the micro-liquid-based dilution method. The results indicated that ctf1 deletion decreased the susceptibility of A. fumigatus to voriconazole by 2-fold. The decreased antifungal sensitivity of Δctf1 can be attributed to the increased ergosterol content and the overexpression of mdr1, mdr2, and mdr4. Thus, our results on the function of ctf1 contribute to the elucidation of the mechanisms underlying A. fumigatus resistance and the factors associated with A. fumigatus virulence.

Field Assessment of Lamium album in Reducing Mycotoxin Biosynthesis in Winter Wheat Infected by Fusarium culmorum

Fungicides play a crucial role in conventional agriculture for disease control, but their prolonged use raises health and environmental concerns. Fusarium culmorum (F. culmorum), a major wheat pathogen causing Fusarium head blight (FHB) and Fusarium crown rot (FCR), poses significant mycotoxigenic threats. The application of natural plant extracts has been proven to fight against phytopathogenic fungi. This study aimed to a field experiment that was carried out at the Field Experimental Station of the Institute of Plant Protection—National Research Institute in Winna Góra, Poland, during the 2022/2023 season to evaluate the potential of Lamium album (L. album) flower extract as a foliar spray against mycotoxigenic fungi in two winter wheat varieties: Arkadia and Julius. The supercritical carbon dioxide extraction method (SC-CO2) was employed to obtain the L. album flower extract. Ergosterol (ERG) and mycotoxin accumulation in the harvested wheat grains were analyzed using chromatography-based methods. The results demonstrated a notable reduction in ERG content in the field plots treated with L. album flower extract, from 26.07 µg/g (control group) to 8.91 µg/g (extract-treated group) for Arkadia and from 70.02 µg/g (control group) to 30.20 µg/g (extract-treated group) for Julius. The treatment with L. album reduced mycotoxin biosynthesis in both varieties, with deoxynivalenol (DON) and zearalenone (ZEN) production significantly decreased. Additionally, Arkadia exhibited greater resistance to Fusarium infection, and the antifungal effect of L. album was more pronounced than in the Julius variety, which proved to be more sensitive. In conclusion, L. album flower extract exhibited promising antifungal effects in field experiments to fight against F. culmorum in winter wheat varieties, suggesting a potential alternative to synthetic fungicides. However, as complete prevention of mycotoxin contamination was not achieved, further research is warranted to optimize extract concentrations and conduct long-term analyses to consider this plant extract as a sustainable control agent.

Water-in-oil Pickering emulsion using ergosterol as an emulsifier solely

As a crucial component of the fungal cell membranes, ergosterol has been demonstrated to possess surface activity attributed to its hydrophobic region and polar group. However, further investigation is required to explore its emulsification behavior upon migration to the oil–water interface. Therefore, this study was conducted to analyze the interface properties of ergosterol as a stabilizer for water in oil (W/O) emulsion. Moreover, the emulsion prepared under the optimal conditions was utilized to load the water-soluble bioactive substance with the chlorogenic acid as the model molecules. Our results showed that the contact angle of ergosterol was 117.017°, and its dynamic interfacial tension was obviously lower than that of a pure water–oil system. When the ratio of water to oil was 4: 6, and the content of ergosterol was 3.5 % (ergosterol/oil phase, w/w), the W/O emulsion had smaller particle size (438 nm), higher apparent viscosity, and better stability. Meanwhile, the stability of loaded chlorogenic acid was improved under unfavorable conditions (pH 1.2, 90 °C, ultraviolet irradiation, and oxidation), which were 73.87 %, 59.53 %, 62.53 %, and 69.73 %, respectively. Additionally, the bioaccessibility of chlorogenic acid (38.75 %) and ergosterol (33.69 %), and the scavenging rates of the emulsion on DPPH radicals (81.00 %) and hydroxyl radicals (82.30 %) were also enhanced. Therefore, a novel W/O Pickering emulsion was prepared in this work using ergosterol as an emulsifier solely, which has great potential for application in oil-based food and nutraceutical formulations.

Antifungal activity, synergistic effect and mode of action of Caraway (Carum carvi L.) essential oil and carvone against Aspergillus fumigatus

IntroductionCurrently available antifungal therapies often have limitations such as toxicity and the development of resistance. The aim of this study was to investigate the antifungal activity and mode of action of Caraway (Carum carvi L.) essential oil (EO) and its constituent carvone against A. fumigatus, a fungal pathogen responsible for invasive aspergillosis. MethodsCaraway EO was obtained by hydrodistillation, and its antifungal activity was assessed by the broth microdilution method according to the CLSI protocol. The ergosterol content of fungal mycelia was measured using a spectrophotometric method. The mode of action of Caraway EO was assessed by electron microscopy. The interaction between Caraway EO and two known antifungals, itraconazole and caspofungin, was evaluated by determining the fractional inhibitory concentration index (FICI). ResultsAt twofold dilutions ranging from 3.12 to 400 µg/mL, Caraway EO inhibited A. fumigatus growth by 10.27–100 %, with a minimum inhibitory concentration (MIC) of 200 µg/mL, while carvone inhibited fungal growth by 7.31–67.58 %, with an MIC of 400 µg/mL. The IC50 values of the Caraway EO and carvone were 56.09 and 47.68 μg/mL, respectively. Moreover, the minimum fungicidal concentration (MFC) of the Caraway EO was reported to be 400 μg/mL. Both Caraway EO and carvone significantly inhibited ergosterol biosynthesis in A. fumigatus. Caraway EO showed synergistic antifungal activity in combination with itraconazole (FICI=0.38) and additive antifungal activity (FICI=0.75) in combination with caspofungin. ConclusionCaraway EO and its constituent carvone showed strong antifungal activity against A. fumigatus by inhibiting ergosterol biosynthesis and destroying essential compartments of fungal mycelia, such as mitochondria. In addition, the combination of carvone with itraconazole or caspofungin had synergistic/additive effects, suggesting potential therapeutic efficacy for the treatment of A. fumigatus-related infections.

Physical decomposition stage and ergosterol content predict the chemical composition of downed dead wood in Mediterranean dehesas

AbstractDead wood is a key substrate of forests that plays an important role in fertility and productivity. However, dead wood is scarce in traditionally managed forests like Mediterranean dehesas. The chemical composition of downed dead wood in Quercus pyrenaica dehesas was analysed in different physical decomposition stages as a proxy of dead wood decay length. We also assessed the contribution of fungal activity, by quantifying ergosterol, to the chemical composition of deadwood. Chemical analyses included elemental composition determination, thermogravimetry and infrared spectroscopy. Our results showed that both the physical decomposition stage and ergosterol content extensively predicted the chemical composition of Q. pyrenaica dead wood decay processes under field conditions. The physical stage was a better predictor of the C/P ratio and polysaccharides proportion, while ergosterol better predicted P content and the N/P ratio. In other cases like lignin, the relation between ergosterol content and chemical composition varied depending on the physical stage. In addition, environmental local factors differentially affected chemical composition across physical decomposition stages. We conclude that the physical decomposition stage and ergosterol content complementarily contribute to estimate the temporal behaviour of the chemical composition of dead wood in Mediterranean areas. Moreover, we recommend using the FT-IR analysis to assess the nature of temporal chemical changes in downed dead wood. Finally, our study claims to consider the potential impact of local environmental factors, such as air temperature and relative humidity, on dead wood decay processes in traditionally managed forests in the current global change scenario.

Transcriptomic and biochemical analyses reveal the antifungal mechanism of cell-free supernatant from Aspergillus luchuensis YZ-1 against Aspergillus flavus

Aspergillus flavus (A. flavus) and its metabolites, aflatoxins, are widespread in crops and foods, threatening public health. Using chemical fungicides to control A. flavus can pose safety hazards and cause environmental pollution. Therefore, there is an urgent need for safe and effective antifungal agents to control A. flavus. In this study, we isolated Aspergillus luchuensisYZ-1 cell-free supernatant (CFS), volatiles, and mycelial extracts to investigate their inhibitory effects on A. flavus. Results indicate that the CFS exhibited greater efficacy in impeding the growth and synthesis of aflatoxin B1 (AFB1) in A. flavus. Transcriptomic analysis revealed a significant downregulation of lipid metabolism, biosynthesis of other secondary metabolites, and glycan metabolism in A. flavus treated with CFS. Approximately 94% of the genes in the aflatoxin synthesis pathway were significantly downregulated. Furthermore, the CFS treatment significantly increased reactive oxygen species (ROS) production in A. flavus, affected its energy metabolism, and upregulated methane metabolism and the pentose phosphate pathway. We then investigated the inhibitory mechanism of YZ-1 against A. flavus by biochemical analysis. It was further confirmed that CFS had destructive effects in the cell wall and cell membrane of A. flavus, as indicated by leakage of nucleic acids, proteins, alkaline phosphatase (AKP), as well as decreased chitin and ergosterol content. In summary, this study provides novel insights into the mechanisms of CFS against A. flavus, suggesting its potential as a biocontrol agent in food and agriculture.

Antifungal drug resistance in Candida: a special emphasis on amphotericin B.

Invasive fungal infections in humans caused by several Candida species, increased considerably in immunocompromised or critically ill patients, resulting in substantial morbidity and mortality. Candida albicans is the most prevalent species, although the frequency of these organisms varies greatly according to geographic region. Infections with C. albicans and non-albicans Candida species have become more common, especially in the past 20 years, as a result of aging, immunosuppressive medication use, endocrine disorders, malnourishment, extended use of medical equipment, and an increase in immunogenic diseases. Despite C. albicans being the species most frequently associated with human infections, C. glabrata, C. parapsilosis, C. tropicalis, and C. krusei also have been identified. Several antifungal drugs with different modes of action are approved for use in clinical settings to treat fungal infections. However, due to the common eukaryotic structure of humans and fungi, only a limited number of antifungal drugs are available for therapeutic use. Furthermore, drug resistance in Candida species has emerged as a result of the growing use of currently available antifungal drugs against fungal infections. Amphotericin B (AmB), a polyene class of antifungal drugs, is mainly used for the treatment of serious systemic fungal infections. AmB interacts with fungal plasma membrane ergosterol, triggering cellular ion leakage via pore formation, or extracting the ergosterol from the plasma membrane inducing cellular death. AmB resistance is primarily caused by changes in the content or structure of ergosterol. This review summarizes the antifungal drug resistance exhibited by Candida species, with a special focus on AmB.

Antifungal potential of lipopeptides produced by the Bacillus siamensis Sh420 strain against Fusarium graminearum.

Biological control is a more sustainable and environmentally friendly alternative to chemical fungicides for controlling Fusarium spp. infestations. In this work, Bacillus siamensis Sh420 isolated from wheat rhizosphere showed a high antifungal activity against Fusarium graminearum as a secure substitute for fungicides. Sh420 was identified as B. siamensis using phenotypic evaluation and 16S rDNA gene sequence analysis. An in vitro antagonistic study showed that Sh420's lipopeptide (LP) extract exhibited strong antifungal properties and effectively combated F. graminearum. Meanwhile, lipopeptides have the ability to decrease ergosterol content, which has an impact on the overall structure and stability of the plasma membrane. The PCR-based screening revealed the presence of antifungal LP biosynthetic genes in this strain's genomic DNA. In the crude LP extract of Sh420, we were able to discover several LPs such as bacillomycin, iturins, fengycin, and surfactins using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Microscopic investigations (fluorescent/transmission electron microscopy) revealed deformities and alterations in the morphology of the phytopathogen upon interaction with LPs. Sh420 LPs have been shown in grape tests to be effective against F. graminearum infection and to stimulate antioxidant activity in fruits by avoiding rust and gray lesions. The overall findings of this study highlight the potential of Sh420 lipopeptides as an effective biological control agent against F. graminearum infestations.IMPORTANCEThis study addresses the potential of lipopeptide (LP) extracts obtained from the strain identified as Bacillus siamensis Sh420. This Sh420 isolate acts as a crucial player in providing a sustainable and environmentally friendly alternative to chemical fungicides for suppressing Fusarium graminearum phytopathogen. Moreover, these LPs can reduce ergosterol content in the phytopathogen influencing the overall structure and stability of its plasma membrane. PCR screening provided confirmation regarding the existence of genes responsible for biosynthesizing antifungal LPs in the genomic DNA of Sh420. Several antibiotic lipopeptide compounds were identified from this bacterial crude extract using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Microscopic investigations revealed deformities and alterations in the morphology of F. graminearum upon interaction with LPs. Furthermore, studies on fruit demonstrated the efficacy of Sh420 LPs in mitigating F. graminearum infection and stimulating antioxidant activity in fruits, preventing rust and gray lesions.

СОВРЕМЕННЫЕ МИКРОБИОЛОГИЧЕСКИЕ ПОДХОДЫ К ПОЛУЧЕНИЮ ШТАММА ХЛЕБОПЕКАРНЫХ ДРОЖЖЕЙ, ПЕРСПЕКТИВНОГО ДЛЯ СОЗДАНИЯ ОБОГАЩЕННЫХ ПИЩЕВЫХ ИНГРЕДИЕНТОВ

The aim of the study is to use modern microbiological approaches to obtain a new strain of baker's yeast. The objects of the study were strains of baker's yeast from the Laboratory of Baker's Yeast Biotechnology of the Institute of Food Biotechnology. Selection and screening of the yeast strain were carried out by clonal plating of the original strain cells on agar media with glucose-asparagine medium (8 % DM) and with malt wort (12 and 18 % DM). The content of crude protein in the yeast biomass was determined by the Kjeldahl method on an automatic BEGER unit (Slovenia). Biomass accumulation was determined by the gravimetric method after cultivation, separating the solid and liquid fractions by centrifugation. Maltase, zymase and proteolytic activities were determined according to known methods. Ergosterol content – spectrophotometric method based on extraction with ethanol and sulfuric acid with triterpene compounds, at a wavelength of λ = 328 nm. The biomass (solid fraction) was separated from the filtrate by centrifugation in a laboratory centrifuge OPM-16 for 15 min at a rotor speed of 6000 rpm. Comparative studies were conducted to select the most productive strain of baker's yeast in terms of biochemical parameters. Comparative characteristics of yeast strains allowed us to select the most promising one – Saccharomyces cerevisiae Y-581, characterized by the ability to a higher level of protein synthesis, maltase, zymase activities, as well as ergosterol and osmosensitivity indicators. A two-stage selection and screening for the above indicators were carried out with the selected strain. As a result of microbiological approaches relative to the original strain S. cerevisiae Y-581, a population of Saccharomyces cerevisiae 581-GA-21c was isolated, characterized by a higher biosynthetic capacity not only in relation to ergosterol and protein, but also to the synthesis of enzymes, especially proteolytic ones. The isolated strain had a higher permeability of the cell membrane, as evidenced by its osmosensitivity indicators. The new strain also had distinctive features in morphological characteristics. This strain will be used in the field of obtaining enriched ingre¬dients for the development of new types of food products.