The Fungal Cell Wall: Candida, Cryptococcus, and Aspergillus Species

A novel mannan-specific chimeric antigen receptor M-CAR redirects T cells to interact with Candida spp. hyphae and Rhizopus oryzae spores

Invasive fungal infections (IFIs) are responsible for elevated rates of morbidity and mortality, causing around of 1.5 million deaths annually worldwide. One of the main causative agents of IFIs is Candida albicans, and non-albicans Candida species have emerged as a spreading global public health concernment. Furthermore, COVID-19 has contributed to a boost in the incidence of IFIs, such as mucormycosis, in which Rhizopus oryzae is the most prevalent causative agent. The effector host immune response against IFIs depends on the activity of T cells, which are susceptible to the regulatory effects triggered by fungal virulence factors. The fungal cell wall plays a crucial role as a virulence factor, and its remodeling compromises the development of a specific T-cell response. The redirection of Jurkat T cells to target Candida spp. by recognizing targets expressed on the fungal cell wall can be facilitated using chimeric antigen receptor (CAR) technology. This study generated an M-CAR that contains an scFv with specificity to α-1,6 mannose backbone of fungal mannan, and the expression of M-CAR on the surface of modified Jurkat cells triggered a strong activation against Candida albicans (hyphae form), Candida tropicalis (hyphae form), Candida parapsilosis (pseudohyphal form), and Candida glabrata (yeast form). Moreover, M-CAR Jurkat cells recognized Rhizopus oryzae spores, which induced high expression of cell activation markers. Thus, a novel Mannan-specific CAR enabled strong signal transduction in modified Jurkat cells in the presence of Candida spp. or R. oryzae.

Mannan is a context-dependent shield that modifies virulence in Nakaseomyces glabratus

Fungal-host interaction outcomes are influenced by how the host recognizes fungal cell wall components. Mannan is a major cell wall carbohydrate and can be a glycoshield that blocks the inner cell wall β-1,3-glucan from activating pro-inflammatory immune responses. Disturbing this glycoshield in Candida albicans results in enhanced antifungal host responses and reduced fungal virulence. However, deletions affecting mannan synthesis can lead to systemic hypervirulence for Nakaseomyces glabratus (formerly Candida glabrata) suggesting that proper mannan architecture dampens virulence for this organism. N. glabratus is the second leading cause of invasive and superficial candidiasis, but little is known about how the cell wall affects N. glabratus pathogenesis. In order to better understand the importance of these species-specific cell wall adaptations in infection, we set out to investigate how the mannan polymerase II complex gene, MNN10, contributes to N. glabratus cell wall architecture, immune recognition, and virulence in reference strains BG2 and CBS138. mnn10Δ cells had thinner inner and outer cell wall layers and elevated mannan, chitin, and β-1,3-glucan exposure compared to wild-type cells. Consistent with these observations, mnn10Δ cells activated the β-1,3-glucan receptor in oral epithelial cells (OECs), EphA2, and caused less OEC damage than wild-type. mnn10Δ replication was also restricted in macrophages compared to wild-type controls. Yet, during systemic infection in Galleria mellonella larvae, mnn10Δ cells induced rapid larval melanization and BG2 mnn10Δ cells killed larvae significantly faster than wild-type. Thus, our data suggest that mannan plays context-dependent roles in N. glabratus pathogenesis, acting as a glycoshield in superficial disease models and modulating virulence during systemic infection.

Exopolysaccharides in microbial interactions: signalling, quorum sensing, and community dynamics

Microbial interactions within diverse ecosystems are intricately governed by the dynamic interplay of exopolysaccharides (EPSs) produced by microorganisms. This review delves into the multifaceted roles of EPS in microbial signalling, quorum sensing (QS), and community dynamics, highlighting their significance in orchestrating cooperative behaviours and shaping community structures. EPSs serve as pivotal signalling molecules, influencing chemical communication and promoting intricate interactions among microorganisms. The integration of EPS into QS mechanisms adds an additional layer of complexity, allowing microorganisms to assess population density and synchronise communal responses. Furthermore, EPSs actively contribute to community dynamics by influencing spatial organisation, adhesion, and resistance to environmental stressors. By providing comprehensive knowledge of EPS dynamics, this review offers valuable insights into microbial ecology, serving as a foundational resource for future research. It will benefit the research community by advancing our understanding of microbial ecosystems, with broad applications in biotechnology, environmental science, and beyond.

Simultaneous electrochemical detection of heavy metal ions using a sol-gel synthesized BiVO4 nanosphere modified electrode and its antimicrobial activity

This study explores the development of an advanced electrochemical sensor designed for the simultaneous detection of Cd2+, Pb2+, Cu2+, and Hg2+ ions. The sensor utilizes sol-gel-synthesized bismuth vanadate (BiVO4) nanospheres, which are integrated onto a glassy carbon electrode (GCE), and employs square wave anodic stripping voltammetry (SWASV) for electrochemical determination of heavy metal ions. The as-prepared sensor demonstrated exceptional analytical performance and offered a wide linear detection range from 0 μM to 110 μM, along with low detection limits of 2.75 μM for Cd2+, 2.32 μM for Pb2+, 2.72 μM for Cu2+, and 1.20 μM for Hg2+ ions. These characteristics made the sensor highly suitable for precise monitoring of heavy metal contamination in both environmental and industrial samples. Beyond their sensing capabilities, the BiVO4 nanospheres also exhibited significant antimicrobial activity against bacterial strains such as E. coli and S. aureus, as well as fungal strains like C. albicans and C. parapsilosis. This antimicrobial effect was attributed to the enhanced surface reactivity and the generation of reactive oxygen species (ROS), which disrupt microbial cellular functions. This dual-functional approach highlighted the substantial progress in both electrochemical sensing and antimicrobial applications. This research presents a strong platform for tackling urgent challenges in environmental monitoring and microbial control.

Cell walls of filamentous fungi - challenges and opportunities for biotechnology

The cell wall of filamentous fungi is essential for growth and development, both of which are crucial for fermentations that play a vital role in the bioeconomy. It typically has an inner rigid core composed of chitin and beta-1,3-/beta-1,6-glucans and a rather gel-like outer layer containing other polysaccharides and glycoproteins varying between and within species. Only a fraction of filamentous fungal species is used for the biotechnological production of enzymes, organic acids, and bioactive compounds such as antibiotics in large amounts on a yearly basis by precision fermentation. Most of these products are secreted into the production medium and must therefore pass through fungal cell walls at high transfer rates. Thus, cell wall mutants have gained interest for industrial enzyme production, although the causal relationship between cell walls and productivity requires further elucidation. Additionally, the extraction of valuable biopolymers like chitin and chitosan from spent fungal biomass, which is predominantly composed of cell walls, represents an underexplored opportunity for circular bioeconomy. Questions persist regarding the effective extraction of these biopolymers from the cell wall and their repurposing in valorization processes. This review aims to address these issues and promote further research on understanding the cell walls in filamentous fungi to optimize their biotechnological use. KEY POINTS: • The highly complex cell walls of filamentous fungi are important for biotechnology. • Cell wall mutants show promising potential to improve industrial enzyme secretion. • Recent studies revealed enhanced avenues for chitin/chitosan from fungal biomass.

Enhanced DNA Extraction From Dimorphic Fungi: Exploring the Advantages of Blastospores Versus Mycelia

The extraction of high-quality DNA from fungi remains a significant challenge due to the structural complexity and resilience of fungal cell walls. This study presents the first comprehensive comparison of DNA extraction efficiency between blastospores (BS) and mycelial cells (MCs) in dimorphic fungi. We evaluated six DNA extraction procedures and two pre-treatment methods to determine their effectiveness in extracting DNA of high quality and yield from both forms. DNA quantification was performed using absolute RT-qPCR targeting the single-copy γ-Actin gene, with specificity and efficiency validated through standardized protocols. Our results showed that BS consistently yielded higher DNA quantity and quality across all conditions, with a mean antilog DNA copy concentration of 5.03 ± 0.20, compared to 2.51 ± 0.20 for MC. DNA quality was superior in BS, as indicated by significantly better 260/280 and 260/230 ratios (31.5% vs. 7.4% for MC, p value = 0.002). Additionally, BS produced higher molecular weight DNA (10,770.5 base pairs vs. 8139.0 base pairs for MC, p value < 0.001) and exhibited greater long-term stability at both 4°C and -20°C. The results demonstrate that BS serve as a more reliable source of high-quality DNA compared to MC. This finding enhances current methodologies in molecular biology and supports more accurate analyses, particularly in studies involving dimorphic fungi.

Chitosan hydrogels: Versatile platforms for drug delivery in cancer treatment, wound dressing, and 3D bioprinting applications

Chitosan, derived from chitin, is frequently employed in various applications, including hydrogels. In cancer treatment, chitosan serves as a drug carrier, enhancing drug bioavailability while reducing side effects. Additionally, its inherent antibacterial properties and ability to maintain a moist environment facilitate faster wound healing. Its capacity for controlled drug release also ensures prolonged delivery of therapeutic agents. Furthermore, its biocompatibility and biodegradability present substantial advantages. Beyond conventional methods, chitosan is now being utilized as a bioink in 3D printing technologies. This innovation enables personalized treatments, leveraging the advantages of chitosan. However, certain challenges must be addressed to ensure the proper application of this technology. This review not only provides comprehensive insights into the synthesis and biomedical applications of chitosan hydrogels but also summarizes recent studies from the past five years, focusing on their roles in wound healing, cancer treatment, and 3D printing applications.

Serum-Stable, Cationic, α-Helical AMPs to Combat Infections of ESKAPE Pathogens and C. albicans

Expedition in the rate of development of antimicrobial resistance accompanied by the slowdown in the development of new antimicrobials has led to a dire necessity to develop an alternate class of antimicrobial agents. Antimicrobial peptides (AMPs), available in nature, are effective molecules that can combat microbial infections. However, due to several inherent shortcomings such as salt sensitivity of their potency, short systemic half-lives owing to protease and serum degradation, and cytotoxicity, their commercial success is limited. Inspired by α helical AMPs present in nature, here in this work, we have developed two short, cationic, helical AMPs RR-12 and FL-13. Both peptides exhibited high broad-spectrum antimicrobial activity, salt tolerance, prompt bactericidal activity, considerable serum stability, remaining non-cytotoxic and non-hemolytic at relevant microbicidal concentrations. The designed AMPs were membranolytic toward the microbial strains, though there were subtle differences in the mechanism owing to the variation in the composition of the cell membranes in different microbes. Rigorous experimental techniques and molecular dynamics (MD) simulations were performed to understand the structure, activity, and their mechanisms in detail. Positive charge, balanced hydrophobicity-hydrophilicity, and helical conformation were the different attributes that led to the development of the superior performance of the AMPs, making them valuable additions to the repertoire of therapeutically promising antimicrobials.

PEG-Mediated Protoplast Transformation of Penicillium sclerotiorum (scaumcx01): Metabolomic Shifts and Root Colonization Dynamics

Protoplast-based transformation is a vital tool for genetic studies in fungi, yet no protoplast method existed for P. sclerotiorum-scaumcx01 before this study. Here, we optimized protoplast isolation, regeneration, and transformation efficiency. The highest protoplast yield (6.72 × 106 cells/mL) was obtained from liquid mycelium after 12 h of enzymatic digestion at 28 °C using Lysing Enzymes, Yatalase, cellulase, and pectinase. Among osmotic stabilizers, 1 M MgSO4 yielded the most viable protoplasts. Regeneration occurred via direct mycelial outgrowth and new protoplast formation, with a 1.02% regeneration rate. PEG-mediated transformation with a hygromycin resistance gene and GFP tagging resulted in stable GFP expression in fungal spores and mycelium over five generations. LC/MS-based metabolomic analysis revealed significant changes in glycerophospholipid metabolism, indicating lipid-related dynamics influenced by GFP tagging. Microscopy confirmed successful colonization of tomato roots by GFP-tagged scaumcx01, with GFP fluorescence observed in cortical tissues. Enzymatic (cellulase) seed pretreatment enhanced fungal colonization by modifying root surface properties, promoting plant-fungal interaction. This study establishes an efficient protoplast transformation system, reveals the metabolic impacts of genetic modifications, and demonstrates the potential of enzymatic seed treatment for enhancing plant-fungal interactions.

Advanced droplet microfluidic platform for high-throughput screening of industrial fungi

Industrial fungi are pivotal candidates for the production of a diverse array of bioproducts. To enhance their productivity, these strains are frequently subjected to genetic modifications. Following transformation, the selection of optimal production strains is critical; however, traditional screening methods often suffer from limitations in throughput and sensitivity. This article explores the transformative potential of Droplet Microfluidic Technology (DMFS) for high-throughput screening of industrial fungi. DMFS enables real-time monitoring and precise single-cell analysis by encapsulating individual fungal spores or cells within droplets, ranging from picoliters to nanoliters, functioning as isolated microreactors. This technology effectively addresses the challenges posed by conventional methods, such as agar plate assays and fluorescence-activated cell sorting. Key advancements discussed include microfluidic chip fabrication, droplet generation and regulation techniques, and multimodal signal detection methods-encompassing fluorescence, Raman spectroscopy, and mass spectrometry. Notably, strategies to mitigate droplet breakage in filamentous fungi, including physical constraints, bionic core-shell hydrogels, and genetic engineering approaches, are analyzed to prolong stable culture times. Future developments will likely emphasize interdisciplinary applications, including automation driven by artificial intelligence and label-free detection methods. We anticipate that this review will catalyze further research into high-quality industrial fungi, thereby promoting sustainable biomanufacturing through enhanced throughput, cost-effectiveness, and scalability.

Synergistic effect of synthetic derivatives of 1,3,4-thiadiazole with amphotericin B in antifungal therapy

Amphotericin B (AmB) is a potent antifungal agent with minimal resistance among clinical isolates, but its use is limited by severe side effects. Reducing its toxicity through combination therapy with synergistic compounds is a promising strategy. This study investigates the antifungal potential of 1,3,4-thiadiazole derivatives, focusing on AT2 and AT10, against Candida species. AT2 demonstrated the highest activity, achieving complete inhibition at 128 µg/mL and notable suppression at lower concentrations. The combination of AT2 and AT10 with amphotericin B exhibited synergistic effects, leading to significant structural alterations in the fungal cell wall, including reduced β-glucan levels and increased synthesis of mannan and phosphomannan. These modifications correlated with enhanced antifungal efficacy without exacerbating cytotoxicity toward human fibroblasts and renal epithelial cells. The spectroscopic analysis suggested that the synergy arose from both cell wall disruptions and amphotericin B disaggregation. These findings highlight the potential of thiadiazole-based combination therapies for combating resistant fungal infections.

Investigating endophytic fungi of Calotropis procera for novel bioactive compounds: molecular docking and bioactivity insights

BACKGROUND

The rising danger of antibiotic resistance and the increasing burden of cancer worldwide have highlighted the necessity for a constant supply of new antimicrobial drugs and anticancer therapies. Endophytic fungi, recognized as a rich supplier of secondary metabolites with novel bioactivities that have shown promising antimicrobial and anticancer potential, were isolated from the medicinal plant Calotropis procera. Approximately 70 segments from the leaves and stems of the C. procera plant were evaluated for endophytic colonization, resulting in the isolation and identification of five fungal species based on morphological characteristics.

RESULTS

A total of five endophytic fungal species were isolated from Calotropis procera and identified, with Aspergillus versicolor exhibiting the highest frequency of occurrence (50%). In contrast, the remaining fungal species were found at a frequency of 25% each. The endophytic fungal filtrates were evaluated for antimicrobial efficacy against seven pathogens, demonstrating significant inhibition zones ranging from 7 to 25 mm. Additionally, the anticancer activity was assessed against two cell lines, MCF-7 and HCT-16, with IC50 ranging from 7.8 to 50.4 µg/mL. Among the isolates, the filtrate of Aspergillus niger (Accession number PQ568010) exhibited the highest antimicrobial and anticancer activities. The crude extract of A. niger was developed to identify the chemical constituents by gas chromatography. The most active component in the extract, as analyzed by 1H NMR, revealed that 2,2,4,4-tetramethylpentane was the primary compound responsible for these effects, which demonstrated significant inhibitory activity against Staphylococcus aureus and Bacillus cereus, with inhibition zones of 23 mm and 20 mm, respectively. Molecular docking studies were performed against Phenylalanine-tRNA ligase alpha subunit of Bacillus cereus (UniProt ID: Q633N4), GTPase Der of Escherichia coli (UniProt ID: P0A6P5), peptidoglycan-N-acetylglucosamine deacetylase of Listeria monocytogenes (UniProt ID: A0A3Q0NBH7), DNA gyrase subunit B of Salmonella typhimurium (UniProt ID: P0A2I3), Zinc metalloproteinase aureolysin of Staphylococcus aureus (UniProt ID: P81177), Agglutinin-like protein 2 of Candida albicans (UniProt ID: Q9URQ0), serine/threonine-protein kinase of Saccharomyces cerevisiae (UniProt ID: P32600).

CONCLUSION

The study highlights the potential of endophytic fungi Aspergillus niger as a promising source of novel antimicrobial and anticancer agents. The identification of 2,2,4,4-tetramethylpentane as the primary bioactive compound, combined with the molecular docking analyses, provides valuable insights into the mechanisms of action and potential therapeutic applications. These findings underscore the importance of exploring endophytic fungi for the development of new drugs to combat antibiotic resistance and cancer.

Production of β-Glucans from Rhizopus oryzae M10A1 by Optimizing Culture Conditions Using Liquid Potato Starch Waste

β-glucans from filamentous fungi are important for human health. There is limited research on polysaccharides from filamentous fungi, and no reports have been published regarding the optimization of culture media to produce β-glucans from Rhizopus oryzae using liquid waste from potato starch processing. In this regard, the fermentation conditions to produce β-glucans from Rhizopus oryzae M10A1 were optimized using the one variable at a time (OVAT) and response surface methodology (RSM). The β-glucans were chemically characterized by determining moisture, nitrogen, protein, fat, ash, and total carbohydrates. The color, molecular weight, β-glucan content, monosaccharide composition, and structural and conformational characteristics were assessed by colorimetry, gel permeation chromatography, high-performance liquid chromatography, and Fourier transform infrared spectroscopy, respectively. The microbial indicators, mesophilic aerobes, molds, yeasts, and Escherichia coli were quantified following ISO standard protocols. Optimization indicated that supplementation with 0.8% (w/v) glucose and ammonium sulfate enhanced heteroglycan production (3254.56 mg/100 g of biomass). The β-glucans exhibited high purity, a light brown color, a molecular weight of 450 kDa, and a composition predominantly consisting of glucose and galactose. These findings suggest that β-glucans from Rhizopus oryzae M10A1 could be used for food and health applications.

Atomic Insights Into Self-Assembly of Zingibroside R1 and its Therapeutic Action Against Fungal Diseases

Natural products are a crucial resource for drug discovery, but poor understanding of the molecular-scale mechanisms of their self-assembly into soluble, bioavailable hydrogels limits their applications and therapeutic potential. It is demonstrated that Zingibroside R1 (ZR1), derived from Panax notoginseng, undergoes spontaneous self-assemble into a hydrogel comprising helical nanofibrils with potent antifungal activity lacking in its monomeric state. Cryogenic electron microscopy (cryo-EM) revealed an intricate hydrogen-bonding network that facilitates ZR1 nanofibril formation, characterized by a hydrophobic core and hydrophilic exterior architecture, which underpin its binding activity with cell wall in the vulvovaginal candidiasis (VVC) pathogen, C. albicans. The hydrogen-bonding interface between ZR1 gel and glucan compromises membrane integrity, inhibiting C. albicans proliferation in vitro and in VVC model mice in vivo. ZR1 gel could also deliver probiotic Lactobacillus, synergistically inhibiting VVC and restoring the vaginal microenvironment. This study advances the mechanistic understanding of ZR1's structure-function relationships, offering valuable insights into the rational design and therapeutic optimization of natural product-based hydrogels.

Expression of endochitinase and exochitinase in lettuce chloroplasts increases plant biomass and kills fungal pathogen Candida albicans

Lettuce (Lactuca sativa) is a popular leafy vegetable with global production of ~28 million Mt, cultivated >1 million hectares, with a market value of US$ 4 billion in 2022. However, lettuce is highly susceptible to fungal pathogens that drastically reduce biomass and quality due to spoilage/rot. Therefore, in this study, we investigated the expression of chitinase genes via the lettuce chloroplast genome to enhance biomass and disease resistance. Site-specific integration of the expression cassette into chloroplast genomes was confirmed using two sets of PCR primers. Homoplasmy in transplastomic lines was confirmed in Southern blots by the absence of untransformed genomes. Maternal inheritance of transgenes was confirmed by the lack of segregation when seedlings were germinated in the selection medium. Chitinases expressed in chloroplasts are active in a broad range of pH (5-9) and temperatures (20-50 °C). Exochitinase expression significantly increased the number of leaves, root or shoot length and biomass throughout the growth cycle. Endochitinase expression reduced root/shoot biomass at early stages but recovered in older plants. Plant extracts expressing endochitinase/exochitinase showed activities as high as purified commercial enzymes. Antifungal activity in Candida albicans cultures inhibited growth up to 87%. A novel Carbotrace 680™ Optotracer binding to the ß-1,4 linkages of chitin, evaluated for the first time in plant systems, is highly sensitive to measure chitinase activity. To the best of our knowledge, this is the first report of chitinase expression via the chloroplast genomes of an edible plant, to confer desired agronomic traits or for biomedical applications.

Production of yeast cell wall polysaccharides-β-glucan and chitin by using food waste substrates: Biosynthesis, production, extraction, and purification methods

Food waste causes significant environmental and economic challenges worldwide, prompting many nations to prioritize its reduction and recycling. As a nutrient-rich material containing vitamins, proteins, and carbohydrates, it serves as a promising substrate for the cultivation of single-cell microorganisms like yeast. Yeast cell wall polysaccharides (YCWPs), particularly chitin and β-glucans, offer valuable applications in food, pharmaceuticals, and bioprocessing. This review highlights the biosynthesis, production, extraction, and purification of YCWP cultivated on food waste substrates. Key species including Saccharomyces cerevisiae, Pichia pastoris, and Candida spp. are discussed, with a focus on optimizing chitin and β-glucan yield through mechanical, chemical, and enzymatic extraction methods. In addition, the structural and functional properties of β-glucans and chitin in maintaining cell wall stability are explored, emphasizing their potential as prebiotics, dietary fibers, and biodegradable packaging materials. This review also examines the valorization of food waste in yeast cultivation, presenting a sustainable bioprocessing strategy for transforming waste into valuable bioproducts.

Altering the ligand specificity of DectiSomes

DectiSomes are drug-loaded liposomes coated with pathogen receptors, such as the C-type lectins (CTL) Dectin-2 (D2) and Dectin-3 (D3, MCL). Floating on the surface of DectiSomes, the carbohydrate recognition domains (CRDs) of these CTLs form dimers that bind their cognate oligoglycan ligands. We have shown previously that amphotericin B (AmB)-loaded DectiSomes, D2-AmB-LLs and D3-AmB-LLs, are effective at binding and killing diverse pathogenic fungi. The best-known ligands of Dectin-2 and Dectin-3 in the Candida albicans cell wall and exopolysaccharide matrix include a wide variety of oligomannans. When D2-AmB-LLs or D3-AmB-LLs were labeled in their lumen with complementary green and red fluorescent proteins, Venus and mCherry, they bound the same overlapping regions of oligoglycans in C. albicans colonies. By contrast, when D2-AmB-LLs and D3-AmB-LLs were labeled on their membrane surfaces with complementary pairs of the small fluorophores FITC and Rhodamine B or with Venus and mCherry, they bound mostly non-overlapping sets of ligands. When the Dectin-2 and Dectin-3 proteins were labeled with the complementary pairs of FITC and Rhodamine, they also bound primarily distinct ligands. We proposed several models to explain these alterations in Dectin and DectiSome ligand specificity. These findings also raise important questions about the ligand binding properties of immuno-liposomes.

Simple growth conditions improve targeted gene deletion in Cryptococcus neoformans

Cryptococcus neoformans infections are a significant cause of morbidity and mortality among AIDS patients and the third most common invasive fungal infection in organ transplant recipients. The cryptococcal cell wall is very dynamic and can be modulated depending on growth conditions. It was reported that when C. neoformans is grown in unbuffered yeast nitrogen base (YNB) for 48 hours, the pH of the media drastically drops, and the cells start to shed their cell walls. With this observation, we sought to determine if YNB-grown cells could be used directly for genetic transformation. To test this, we targeted ADE2 using TRACE (transient CRISPR-Cas9 coupled with electroporation) in YNB-grown or competent cells. Deletion of the ADE2 gene results in red-pigmented colonies, allowing visual confirmation of disruption. We were able to successfully delete ADE2 in YNB-grown cells with better efficiency compared to competent cells. Recent studies have shown that gene deletion can be accomplished using short (50  bp) homology arms in place of the normal long arms (~1 kb). However, it was inefficient, leading to more insertions and gene disruption than gene deletions. We tested short homology with YNB-grown cells vs. competent cells and found that gene deletion was significantly improved in YNB-grown cells, at around 60% compared to 6% in competent cells. This was also observed when we deleted LAC1 with the short arms. Altogether, using simple growth conditions, we have greatly improved the speed and efficiency of cryptococcal genetic transformations.IMPORTANCEThe World Health Organization recently ranked C. neoformans as the highest-priority fungal pathogen based on unmet research and development needs and its public health importance. Understanding cryptococcal pathogenicity is key for developing treatments. We found that using simple growth conditions can greatly improve the speed and efficiency of cryptococcal genetic transformations. This finding will advance the field by expanding the ease of cryptococcal genetic manipulations.

The Antifungal Effects of Equol Against Candida albicans Involve Mitochondrial Dysfunction

Novel antifungal agents are urgently needed because of the increasing number of drug-resistant Candida strains encountered in clinical practice and the limited variety of available antifungal drugs. Equol, a metabolite of soy isoflavone glycosides, exhibits antifungal activities. In this study, Equol had good inhibitory activity against Candida species. The lowest inhibitory concentration of 125-500 μg/mL was confirmed by the gradient dilution method. In addition, transmission electron microscopy and the relative content assay showed that Equol altered the cell wall and membrane of Candida albicans. Further studies found that Equol treatment increased the intracellular levels of reactive oxygen species and Ca2+. Subsequent experiments suggested that Equol treatment depolarized the membrane potential of C. albicans and up-regulated the expression of the apoptosis-inducing factor gene. These results confirmed that Equol damaged the cell wall and membrane, dysregulated the intracellular components, induced oxidative stress and Ca2+ accumulation, and ultimately resulted in mitochondrial dysfunction. Collectively, these findings demonstrated that Equol is a potential antifungal agent.

Intratumor fungi specific mechanisms to influence cell death pathways and trigger tumor cell apoptosis

Cancer, uncontrolled cell growth due to the loss of cell cycle regulation, is often found to be associated with viral infections and, as recent studies show, with bacterial infections as well. Emerging reports also suggest a strong link between fungi and cancer. The crucial virulence trait of fungi, the switch from yeast (Y) to hyphal (H) form, is found to be associated with carcinogenesis. The physicochemical properties and signal transduction pathways involved in the switch to the hyphal form overlap with those of tumor cell formation. Inhibiting differentiation causes apoptosis in fungi, whereas preventing apoptosis leads to cancer in multicellular organisms. Literature on the fungi-cancer linkage, though limited, is increasing rapidly. This review examines cancer-specific fungal communities, the impact of fungal microbiome on cancer cell progression, similarities between fungal differentiation and cells turning cancerous at biochemical and molecular levels, including the overlaps in signal transduction pathways between fungi and cancer. Based on the available evidence, we suggest that molecules inhibiting the yeast-hyphal transition in fungi can be combined with those targeting tumor cell apoptosis for effective cancer treatment. The review points out fertile research areas where mycologists and cancer researchers can collaborate to unravel common molecular mechanisms. Moreover, antibodies targeting fungal-specific chitin and glucan can be used for the selective neutralization of tumor cells. These new combinations of potential therapies are expected to facilitate the development of target-specific, less harmful and commercially feasible anticancer therapies. We bring together available evidence to argue that fungal infections could either trigger cancer or have a significant role in the development and progression of cancer. Hence, cancer-associated fungal populations could be utilized as a target for a combination therapy involving the integration of anticancer and antifungal drugs as well as inhibitors of fungal morphogenesis to develop more effective anticancer therapies.

Expanding the Variety of Pyridinium-Based Bis-QACs with Antimicrobial Properties: Investigation into Linker Structure-Activity Correlation

For decades quaternary ammonium compounds (QACs) have served as main component of a top antiseptic and disinfectant compositions. Among them, bis-QACs are the most prominent and effective class of biocides. Although mono-QACs still dominate the antiseptic market, their activity against Gram-negative bacteria is largely inferior to bis-QACs. Moreover, the new wave of bacterial resistance during the COVID-19 pandemic is threatening the efficiency of popular antiseptics. Therefore, the requirement for novel biocides is urgent. Reported here is a unified and simple two-step synthesis to achieve novel biocide's architectures with aromatic linkers. Thus, a series of 14 bis-QACs have been prepared using an Ullman-type reaction following by N-alkylation. The most prominent compounds showed strong bioactivity against a panel of nineteen microbial pathogens, multi-resistant bacterial ESKAPEE strains, fungi and biofilms, including strains, which acquired resistance during COVID-19 in 2021. Moreover, significant improvements in antibiofilm action were observed, where bis-QACs 5 c and 6 a outperformed gold standard pyridinium antiseptic octenidine. These findings will serve as a good basis for further studies of bis-QACs architectures as highly effective biocides.

Occurrence of Moulds and Yeasts in the Slaughterhouse: The Underestimated Role of Fungi in Meat Safety and Occupational Health

Despite their potential impact on meat safety and occupational health, fungi are often underestimated contaminants in slaughterhouses. Moulds and yeasts may be associated with meat contamination in multiple processing stages, and mycotoxigenic species, such as Aspergillus, Fusarium, and Penicillium, pose food safety concerns. Bioaerosols may carry infectious fungi at the slaughterhouse that are capable of causing respiratory conditions and allergies. Chronic exposure to mycotoxins can have hepatotoxic, nephrotoxic, and carcinogenic effects in humans. While bacterial contamination in meat has been widely studied, fungal contamination remains overlooked due to limited evidence of immediate disease and the perception that its risks are lower than those of bacteria, which may contribute to insufficient research, awareness, and standardised surveillance protocols. This review compiles published data on the occurrence of fungi in slaughterhouses over the past twenty-five years. It highlights the primary mould and yeast isolated species, mainly identified based on morphological and microscopic characteristics, providing context for their role in meat safety and occupational health. The findings emphasise the need for improved risk assessment and fungal monitoring in meat plants. Standardised fungal detection and control protocols are also suggested for implementation to enhance meat safety and workplace conditions.

Candida albicans: the current status regarding vaginal infections

Vaginal infections caused by Candida albicans are a significant global health concern due to their recurrence and negative impact on quality of life. This review examines the pathogenesis of C. albicans infections, emphasizing critical virulence factors such as biofilm formation, adherence, and phenotypic switching. Risk factors include immune system suppression, antibiotic use, and hormonal changes, all of which can lead to fungal overgrowth and infection. Current prevention and/or treatment strategies primarily rely on antifungal therapies, personal hygiene practices, and probiotics. However, challenges like antifungal resistance, recurrence, and limited treatment efficacy highlight the need for innovative approaches. Therefore, emerging methods such as novel antifungal agents, vaccines, and nanotechnology-based delivery systems offer promising advancements to improve infection control. Additionally, the immune system plays a key role in preventing C. albicans infections, with both innate and adaptive immunity acting to restrict fungal colonization and growth. Commercially available products, such as antifungal creams, vaginal probiotics, and hygiene solutions, are practical options but often lack long-term efficacy. Persistent challenges, including resistance, patient noncompliance, and restricted access to emerging therapies, hinder comprehensive prevention and treatment efforts. Thus, future research should focus on promoting interdisciplinary approaches, integrating personalized medicine, and enhancing healthcare accessibility. This review intends to present the current state of the art within the abovementioned issues and to enhance the understanding of the multifactorial nature of C. albicans infections and advanced prevention strategies, which are essential to reduce the burden of vaginal candidiasis worldwide and improve patient quality of life outcomes. KEY POINTS: • Candida albicans pathogenesis involves biofilms, adherence, and phenotypic switching. • Vaccines, nanotechnology, and new drugs offer improved prevention and treatment. • Addressing antifungal resistance and patient compliance is key for prevention success.

Self-disassembling nanoparticles as oral nanotherapeutics targeting intestinal microenvironment

Inspired by the survival strategies of pyomelanin-producing microbes, we synthesize pyomelanin nanoparticles (PMNPs) from homogentisic acid- γ-lactone via auto-oxidation and investigate their biomedical potential. PMNPs possess distinct physicochemical properties, including reactive oxygen species scavenging and microenvironment-responsive self-disassembly. Under intestinal conditions, PMNPs self-disassemble and penetrate the nanoscale pores of the mucin layer. In an inflammatory bowel disease model, orally administered PMNPs withstand gastric acidity and, in their solubilized form, interact with macrophages and epithelial cells. They significantly reduce reactive oxygen species levels, exert anti-inflammatory effects, and restore gut microbiota composition. Compared to conventional nanoparticles and 5-aminosalicylic acid, PMNPs exhibit greater therapeutic efficacy. Clinical symptoms and intestinal inflammation are alleviated, and the gut microbiota is restored to near-normal levels. These findings underscore the therapeutic potential of PMNPs for inflammatory bowel disease treatment and suggest broader biomedical applications.

Exploring Broad-Spectrum Antimicrobial Nanotopographies: Implications for Bactericidal, Antifungal, and Virucidal Surface Design

Inspired by the natural defense strategies of insect wings and plant leaves, nanostructured surfaces have emerged as a promising tool in various fields, including engineering, biomedical sciences, and materials science, to combat bacterial contamination and disrupt biofilm formation. However, the development of effective antimicrobial surfaces against fungal and viral pathogens presents distinct challenges, necessitating tailored approaches. Here, we aimed to review the recent advancements of the use of nanostructured surfaces to combat microbial contamination, particularly focusing on their mechano-bactericidal and antifungal properties, as well as their potential in mitigating viral transmission. We comparatively analyzed the diverse geometries and nanoarchitectures of these surfaces and discussed their application in various biomedical contexts, such as dental and orthopedic implants, drug delivery systems, and tissue engineering. Our review highlights the importance of preventing microbial attachment and biofilm formation, especially in the context of rising antimicrobial resistance and the economic impact of biofilms. We also discussed the latest progress in materials science, particularly nanostructured surface engineering, as a promising strategy for reducing viral transmission through surfaces. Overall, our findings underscore the significance of innovative strategies to mitigate microbial attachment and surface-mediated transmission, while also emphasizing the need for further interdisciplinary research in this area to optimize antimicrobial efficacy and address emerging challenges.

Optimizing fungal DNA extraction and purification for Oxford Nanopore untargeted shotgun metagenomic sequencing from simulated hemoculture specimens

Long-read metagenomics provides a promising alternative approach to fungal identification, circumventing methodological biases, associated with DNA amplification, which is a prerequisite for DNA barcoding/metabarcoding based on the primary fungal DNA barcode (Internal Transcribed Spacer (ITS) region). However, DNA extraction for long-read sequencing-based fungal identification poses a significant challenge, as obtaining long and intact fungal DNA is imperative. Comparing different lysis methods showed that chemical lysis with CTAB/SDS generated DNA from pure fungal cultures with high yields (ranging from 11.20 ± 0.17 µg to 22.99 ± 2.22 µg depending on the species) while preserving integrity. Evaluating the efficacy of human DNA depletion protocols demonstrated an 88.73% reduction in human reads and a 99.53% increase in fungal reads compared to the untreated yeast-spiked human blood control. Evaluation of the developed DNA extraction protocol on simulated clinical hemocultures revealed that the obtained DNA sequences exceed 10 kb in length, enabling a highly efficient sequencing run with over 80% active pores. The quality of the DNA, as indicated by the 260/280 and 260/230 ratios obtained from NanoDrop spectrophotometer readings, exceeded 1.8 and 2.0, respectively. This demonstrated the great potential of the herein optimized protocol to extract high-quality fungal DNA from clinical specimens enabling long-read metagenomics sequencing.

IMPORTANCE

A novel streamlined DNA extraction protocol was developed to efficiently isolate high molecular weight fungal DNA from hemoculture samples, which is crucial for long-read sequencing applications. By eliminating the need for labor-intensive and shear-force-inducing steps, such as liquid nitrogen grinding or bead beating, the protocol is more user-friendly and better suited for clinical laboratory settings. The automation of cleanup and extraction steps further shortens the overall turnaround time to under 6 hours. Although not specifically designed for ultra-long DNA extraction, this protocol effectively supports fungal identification through Oxford Nanopore Technology (ONT) sequencing. It yields high molecular weight DNA, resulting in longer sequence fragments that improve the number of fungal reads over human reads. Future improvements, including adaptive sampling technology, could further simplify the process by reducing the need for human DNA depletion, paving the way for more automated, bioinformatics-driven workflows.

MNN45 is involved in Zcf31-mediated cell surface integrity and chitosan susceptibility in Candida albicans

Candida albicans is a major human fungal pathogen; however, limited antifungal agents, undesirable drug side effects, and ineffective prevention of drug-resistant strains have become serious problems. Chitosan is a nontoxic, biodegradable, and biocompatible linear polysaccharide made from the deacetylation of chitin. In this study, a ZCF31 putative transcription factor gene was selected from a previous mutant library screen, as zcf31Δ strains exhibited defective cell growth in response to chitosan. Furthermore, chitosan caused notable damage to zcf31Δ cells; however, ZCF31 expression was not significantly changed by chitosan, suggesting that zcf31Δ is sensitive to chitosan could be due to changes in the physical properties of C. albicans. Indeed, zcf31Δ cells displayed significant increases in cell wall thickness. Consistent with the previous study, zcf31Δ strains were resistant to calcofluor white but highly susceptible to SDS (sodium dodecyl sulfate). These results implied that chitosan mainly influences membrane function, as zcf31Δ strengthens the stress resistance of the fungal cell wall but lessens cell membrane function. Interestingly, this effect on the cell surface mechanics of the C. albicans zcf31Δ strains was not responsible for the virulence-associated function. RNA-seq analysis further revealed that six mannosyltransferase-related genes were upregulated in zcf31Δ. Although five mannosyltransferase-related mutant strains in the zcf31Δ background partially reduced the cell wall thickness, only zcf31Δ/mnn45Δ showed the recovery of chitosan resistance. Our findings suggest that Zcf31 mediates a delicate and complicated dynamic balance between the cell membrane and cell wall architectures through the mannosyltransferase genes in C. albicans, leading to altered chitosan susceptibility.

Glucuronoxylomannan (GXM) modulates macrophage proliferation and apoptosis through the STAT1 signaling pathway

cryptococcus neoformans (C. neoformans) is a crucial opportunistic fungus that possesses an encapsulated fungal pathogen. The cryptococcal capsule is mainly composed of the polysaccharide glucuronoxylomannan (GXM). Macrophages form the first-line innate defense against cryptococcosis; however, the underlying mechanism remains unclear. In this study, GXM-treated RAW264.7 macrophages showed a notably reduced survival rate and increased apoptosis, accompanied by the promoted inducible nitric oxide synthase (iNOS) expression and NO production. Signal transducer and activator of transcription 1 (STAT1) expression was also found to be directly proportional to GXM concentration; STAT1 knockdown could alleviate GXM-induced proliferation decrease and apoptosis increase of macrophages, as well as reduce M1 polarization, iNOS expression and NO release. In conclusion, this study concluded that GXM was the main virulence factor of C. neoformans, which is critical in determining the mechanism of GXM-mediated protective immune response postinfection. The STAT1 signal pathway mediates the effect of GXM stimulation on macrophages, potentially providing a reference for further understanding the biological role of GXM.

Chitin estimation in agricultural soils

The present scientific report has been elaborated in the context of the European Commission mandate requesting for an opinion according to Article 23(6) of Regulation (EC) No 1107/2009 regarding the approved plant protection uses of chitosan and chitosan hydrochloride as basic substances. This scientific report focused on estimating the amount of chitin present in an average agricultural soil, aiming to establish a baseline for its natural availability. Understanding the source and concentration of biotic chitin in soil assisted the estimation of chitosan potentially available in the environment, as requested in one of terms of reference of the concerned EC mandate. Chitin in soil was estimated to range from 27 to 280 kg/ha in the first 0-5 cm layer and 99 to 901 kg/ha in the 0-20 cm layer. Fungi are the main chitin producer followed by insects and nematodes. Soil crustaceans could not be considered in the assessment due to the lack of necessary information and the variability of their presence. The development of a polynomial function to estimate the amount of chitin in such biome can also identify the main predictors of chitin content in similar biomes. This estimate was based on the available scientific literature, and it would require additional validation using field measurements and error analysis on different soil types and conditions, to become a generalised model. Lack of information alongside related uncertainties have also been identified.

The brightness of lectins conjugated to quantum dots

One of the main focuses of glycobiology is investigating the synthesis and modification of carbohydrates in biological systems, due to their involvement in various processes such as cell recognition, differentiation, and immune response. Since the study of these glycans contributes to the understanding of complex biological functions, these biochemical compounds can be analyzed using lectins, which are ubiquitous proteins in nature capable of specifically recognizing carbohydrates. In addition, lectin-carbohydrate interaction can be visualized by conjugating these proteins with quantum dots (QDs), which are fluorescent nanoprobes with advantageous properties, including photostability and size-tunable emission. QDs also possess chemically active surfaces that enable the attachment of biomolecules, such as lectins. In this review, we provide detailed reports of studies involving QD-lectin conjugates conducted by the Biomedical Nanotechnology Group at the Federal University of Pernambuco (UFPE/Brazil) and its collaborators. An integrated perspective on the use of QD-lectin conjugates to study saccharides in a range of biological systems, from bacteria and fungi to red blood cells and cancer tissues, is also presented. We hope this comprehensive review inspires further studies exploring the brightness of lectins upon conjugation with QDs to unravel glycobiological processes.

Resilience in Resistance: The Role of Cell Wall Integrity in Multidrug-Resistant Candida

The Candida species cell wall plays a pivotal role as a structural and functional barrier against external aggressors and as an intermediary in host-pathogen interactions. Candida species exhibit unique adaptations in their cell wall composition, with varying proportions of chitin, mannans, and β-glucans influenced by the environmental conditions and the morphological states. These components not only maintain cellular viability under osmotic, thermal, and chemical stress, but also serve as the key targets for novel antifungal strategies. MAPK signaling pathways, like the cell wall integrity pathway and the high-osmolarity glycerol pathway, play a crucial role in responding to cell wall stressors. Due to the rise of antifungal resistance and its clinical challenges, there is a need to identify new antifungal targets. This review discusses the recent advances in understanding the mechanisms underlying cell wall integrity, their impact on antifungal resistance and virulence, and their potential as therapeutic targets of C. albicans, N. glabratus, and C. auris.

Unveiling the fungal frontier: mycological insights into inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic recurrent gastrointestinal disease that seriously affects the quality of life of patients around the world. It is characterized by recurrent abdominal pain, diarrhea, and mucous bloody stools. There is an urgent need for more accurate diagnosis and effective treatment of IBD. Accumulated evidence suggests that gut microbiota plays an important role in the occurrence and development of gut inflammation. However, most studies on the role of gut microbiota in IBD have focused on bacteria, while fungal microorganisms have been neglected. Fungal dysbiosis can activate the host protective immune pathway related to the integrity of the epithelial barrier and release a variety of pro-inflammatory cytokines to trigger the inflammatory response. Dectin-1, CARD9, and IL-17 signaling pathways may be immune drivers of fungal dysbacteriosis in the development of IBD. In addition, fungal-bacterial interactions and fungal-derived metabolites also play an important role. Based on this information, we explored new strategies for IBD treatment targeting the intestinal fungal group and its metabolites, such as fungal probiotics, antifungal drugs, diet therapy, and fecal microbiota transplantation (FMT). This review aims to summarize the fungal dysbiosis and pathogenesis of IBD, and provide new insights and directions for further research in this emerging field.

An innovative high-throughput genome releaser for rapid and efficient PCR screening

High-throughput PCR screening is vital in synthetic biology and metabolic engineering, enabling rapid and precise analysis of genetic modifications. However, current methods face challenges including inefficient DNA extraction, high variability across sample types, scalability limitations, and the high cost of template DNA extraction. To address these common challenges, we developed a High-Throughput Genome Releaser (HTGR). This innovative device utilizes a squash-based method for rapid, cost-effective, and efficient DNA extraction, optimized for subsequent PCR reactions. After testing various synthetic materials, we selected a plastic that closely mimics the smooth surface and compression properties of microscope slides, ensuring reliable and consistent performance. The device comprises a 96-well plate and a Shear Applicator, designed for both manual and automated operation, and is compatible with standard liquid-handling robotic platforms. This compatibility simplifies integration into high-throughput PCR workflows. Additionally, we developed software to support its automated functions. Our results demonstrated that the specially engineered 96-well plate and HTGR effectively squash fungal spores, releasing sufficient genomic DNA for PCR screening with 100% efficiency. The genome releaser enables the preparation of PCR-ready genomic DNA from 96 samples within minutes, eliminating the need for an extraction buffer. Its adaptability to a wide range of microorganisms and cell types makes it a versatile tool that could significantly advance biomanufacturing processes.

The role of Npt1 in regulating antifungal protein activity in filamentous fungi

Pathogenic filamentous fungi pose a significant threat to global food security and human health. The limitations of available antifungal agents, including resistance and toxicity, highlight the need for developing innovative antifungal strategies. Antifungal proteins (AFPs) are a class of secreted small proteins that exhibit potent antifungal activity against filamentous fungi, yet the underlying mechanism remains partially understood. In this study, we investigate the molecular and cellular effects of two AFPs, PgAFP and AfAFP, on Aspergillus flavus, a representative filamentous fungus. These AFPs affect various fungal phenotypes and exert an intracellular effect by interacting with Ntp1, a fungi exclusive protein modulating diverse fungal traits. We find that Ntp1 amino acids 417-588 are critical for AFP binding and play a role in regulating growth, development, sporulation, sclerotia formation, toxin synthesis, and pathogenicity. Results generated from this study will help to control pathogenic fungi.

Solid-state NMR observation of chitin in whole cells by indirect 15N detection with NC, NCC, CNC and CNCC polarization transfers

Chitin is the most important nitrogen-containing polysaccharide found on Earth. This polysaccharide is a polymer of an N-acetylglucosamine and it is a crucial structural component of fungal cell walls and crustaceans. Magic-angle spinning solid-state NMR is emerging as a powerful analytical approach to study polysaccharides in the context of intact cell walls and whole cells. The presence of an acetamido group in chitin is attractive for 15N solid-state NMR. Here we investigate the use of various multi-step polarization transfer experiments incorporating indirect 15N detection at moderate spinning frequency, adapted from pulse sequences commonly employed for residue resonance assignment in biosolid proteins. The 13C,15N chitin spin topology slightly differs from amino acids, and we discussed the use of frequency-selective 15N-13C cross-polarization transfers followed by broadband or frequency-selective homonuclear 13C-13C transfers to detect chitin resonances. Demonstrated here for chitin found in the cell wall of the fungus Aspergillus fumigatus, the use of indirect 15N detection through multi-step polarization transfers could be advantageous to investigate more complex nitrogen-containing polysaccharides found in whole cells and peptidoglycan samples.

Gfa1 (glutamine fructose-6-phosphate aminotransferase) is essential for Aspergillus fumigatus growth and virulence

BACKGROUND

Aspergillus fumigatus, the primary etiological agent of invasive aspergillosis, causes over 1.8 million deaths annually. Targeting cell wall biosynthetic pathways offers a promising antifungal strategy. Gfa1, a rate-limiting enzyme in UDP-GlcNAc synthesis, plays a pivotal role in the hexosamine biosynthetic pathway (HBP).

RESULTS

Deletion of gfa1 (Δgfa1) results in auxotrophy for glucosamine (GlcN) or N-acetylglucosamine (GlcNAc). Under full recovery (FR) conditions, where minimal medium is supplemented with 5 mM GlcN as the sole carbon source, the Δgfa1 mutant shows growth comparable to the wild-type (WT). However, when supplemented with 5 mM GlcN and 55 mM glucose, growth is partially repressed, likely due to carbon catabolite repression, a condition termed partial repression (PR). Under PR conditions, Δgfa1 exhibits compromised growth, reduced conidiation, defective germination, impaired cell wall integrity, and increased sensitivity to endoplasmic reticulum (ER) stress and high temperatures. Additionally, Δgfa1 demonstrates disruptions in protein homeostasis and iron metabolism. Transcriptomic analysis of the mutant under PR conditions reveals significant alterations in carbohydrate and amino acid metabolism, unfolded protein response (UPR) processes, and iron assimilation. Importantly, Gfa1 is essential for A. fumigatus virulence, as demonstrated in Caenorhabditis elegans and Galleria mellonella infection models.

CONCLUSIONS

These findings underscore the critical role of Gfa1 in fungal pathogenicity and suggest its potential as a therapeutic target for combating A. fumigatus infections.

Natural synthesis of β-glucan nanoparticles via microwave for breast cancer prevention: a study on oats-derived nanoparticles

This study investigates the antibacterial and cancer-preventive properties of β-glucan nanoparticles (GNP) synthesised from oats using microwave energy, sodium tripolyphosphate (TPP), and silver (Ag). UV-visible spectroscopy indicated a strong surface plasmon resonance peak between 220 and 250 nm for GNP. FTIR analysis identified a band at 609 cm-1, signifying β linkage and confirming the presence of β-glucans. SEM imaging showed that the nanoparticles have smooth surfaces with various forms and sizes ranging from 67 to 129 nm, which aligns with the average size of 76-115 nm determined by particle size analysis. The disc diffusion method revealed significant antibacterial activity of GNP and DNA fragmentation confirmed that GNP induced apoptosis in MCF-7 cell lines. The observed IC50 value (50.41-59.34 µg/ml) indicated the dose at which GNP effectively triggers apoptosis highlighting their potent anticancer effects. The selective cytotoxicity towards cancer cells emphasises the need for further exploration of these nanoparticles for targeted cancer therapy.

Synthesis, characterizations and disinfection potency of gelatin based Gum Arabic antagonistic films

Water-borne infections are considered as one of the major risky concerns regarding the sanitary state of water bodies dedicated to drinking water supply. Therefore, the employment of environmentally benign materials in water/wastewater treatment is an indispensable aspect to solve the water crisis problem in an eco-friendly and economic manner. This study describes the synthesis, characterization, and disinfection potency of different formulas of gelatin-based Gum Arabic composites, for the first time. SEM, XRD, FTIR, ζ-potential, and swelling tests were used to assess their physicochemical properties, which revealed the enhanced compatibility and miscibility with increasing Gum Arabic concentration. The formula of GEL/50%GA showed more homogenously distributed pores as visualized by SEM with noticeable shifts in the characteristic FTIR-band and more negatively charged surface, reflecting the considerable stability as indicated by ζ-potential. Besides, it also had superior hydrophilic and swellability levels. Interestingly, the results of antimicrobial activity showed the susceptibility of broad-spectrum microbes against examined composites, especially with elevating the concentration of Gum Arabic incorporated in the composite. As a natural alternative disinfectant, the as-prepared composites (3 and 10% W/V) were evaluated in the disinfection of real wastewater samples. The results revealed that GEL/50%GA (10% W/V) exhibited a noticeable reduction in total plate count by 45.62 ± 1.48% and 37.48 ± 1.63% and in coliforms by 58.43 ± 2.07% and 40.88 ± 2.24% for municipal and industrial effluents, respectively. However, the microbial metabolic activity via MTT assay was diminished by more than 50% in both effluents; denoting the efficient inhibiting capability of GEL supplemented with GA films in restricting microbial viability even in unculturable microbes. Overall, the antagonistic activity of examined composites offers promising insights for recruitment in different disciplines such as anti-biofouling membranes, food coating, dietary supplements, wound healing, and drug delivery.

Spray-induced gene silencing to control plant pathogenic fungi: A step-by-step guide

RNA interference (RNAi)-based control technologies are gaining popularity as potential alternatives to synthetic fungicides in the ongoing effort to manage plant pathogenic fungi. Among these methods, spray-induced gene silencing (SIGS) emerges as particularly promising due to its convenience and feasibility for development. This approach is a new technology for plant disease management, in which double-stranded RNAs (dsRNAs) targeting essential or virulence genes are applied to plants or plant products and subsequently absorbed by plant pathogens, triggering a gene silencing effect and the inhibition of the infection process. Spray-induced gene silencing has demonstrated efficacy in laboratory settings against various fungal pathogens. However, as research progressed from the laboratory to the greenhouse and field environments, novel challenges arose, such as ensuring the stability of dsRNAs and their effective delivery to fungal targets. Here, we provide a practical guide to SIGS for the control of plant pathogenic fungi. This guide outlines the essential steps and considerations needed for designing and assessing dsRNA molecules. It also addresses key challenges inherent to SIGS, including delivery and stability of dsRNA molecules, and how nanoencapsulation of dsRNAs can aid in overcoming these obstacles. Additionally, the guide underscores existing knowledge gaps that warrant further research and aims to provide assistance to researchers, especially those new to the field, encouraging the advancement of SIGS for the control of a broad range of fungal pathogens.

Synthesis and antifungal activity of novel amide derivatives from quinic acid against the sweet potato pathogen Ceratocystis fimbriata

BACKGROUND

Ceratocystis fimbriata is a fungal pathogen that infects sweet potato roots, producing enormous economic losses. Cyclic polyhydroxy compound quinic acid is a common metabolite synthesized in plant tissues, including sweet potato tubers, showing weak antifungal properties. Although several O-acylated quinic acid derivatives have been synthesized and found in nature and their antifungal properties have been explored, derivatives based on modification of the carboxylic acid have never been evaluated.

RESULTS

In this study, amide derivatives were synthesized via linkage of amines with the carboxylic acid moiety of quinic acid. Derivatives with high dipolar moments and a low number of rotatable bonds showed greater antifungal activities toward C. fimbriata in vitro than quinic and chlorogenic acids. Derivative 5b, which was synthesized by coupling p-aminobenzoic acid (pABA) with quinic acid, had the greatest antifungal activity. 5b showed iron(II)-chelating properties and reduced ergosterol content in C. fimbriata cells, causing irregularities in the fungal cell wall and inhibiting conidia agglutination. Application of 3 mm 5b reduced black rot symptoms in sweet potatoes by 70.1%.

CONCLUSIONS

Collectively, derivatization of the carboxylic acid from quinic acid was demonstrated to be a suitable strategy to improve the antifungal properties of this compound. This study reveals a new efficient strategy for management of the sweet potato pathogen C. fimbriata. © 2024 Society of Chemical Industry.

From glycans to green biotechnology: exploring cell wall dynamics and phytobiota impact in plant glycopathology

Filamentous plant pathogens, including fungi and oomycetes, pose significant threats to cultivated crops, impacting agricultural productivity, quality and sustainability. Traditionally, disease control heavily relied on fungicides, but concerns about their negative impacts motivated stakeholders and government agencies to seek alternative solutions. Biocontrol agents (BCAs) have been developed as promising alternatives to minimize fungicide use. However, BCAs often exhibit inconsistent performances, undermining their efficacy as plant protection alternatives. The eukaryotic cell wall of plants and filamentous pathogens contributes significantly to their interaction with the environment and competitors. This highly adaptable and modular carbohydrate armor serves as the primary interface for communication, and the intricate interplay within this compartment is often mediated by carbohydrate-active enzymes (CAZymes) responsible for cell wall degradation and remodeling. These processes play a crucial role in the pathogenesis of plant diseases and contribute significantly to establishing both beneficial and detrimental microbiota. This review explores the interplay between cell wall dynamics and glycan interactions in the phytobiome scenario, providing holistic insights for efficiently exploiting microbial traits potentially involved in plant disease mitigation. Within this framework, the incorporation of glycobiology-related functional traits into the resident phytobiome can significantly enhance the plant's resilience to biotic stresses. Therefore, in the rational engineering of future beneficial consortia, it is imperative to recognize and leverage the understanding of cell wall interactions and the role of the glycome as an essential tool for the effective management of plant diseases.

Molecular Distinction of Cell Wall and Capsular Polysaccharides in Encapsulated Pathogens by In Situ Magic-Angle Spinning NMR Techniques

Pathogenic fungal and bacterial cells are enveloped within a cell wall, a molecular barrier at their cell surface, and a critical architecture that constantly evolves during pathogenesis. Understanding the molecular composition, structural organization, and mobility of polysaccharides constituting this cell envelope is crucial to correlate cell wall organization with its role in pathogenicity and to identify potential antifungal targets. For the fungal pathogen Cryptococcus neoformans, the characterization of the cell envelope has been complexified by the presence of an additional external polysaccharide capsular shell. Here, we investigate how magic-angle spinning (MAS) solid-state NMR techniques increase the analytical capabilities to characterize the structure and dynamics of this encapsulated pathogen. The versatility of proton detection experiments, dynamic-based filters, and relaxation measurements facilitate the discrimination of the highly mobile external capsular structure from the internal rigid cell wall of C. neoformans. In addition, we report the in situ detection of triglyceride molecules from lipid droplets based on NMR dynamic filters. Together, we demonstrate a nondestructive technique to study the cell wall architecture of encapsulated microbes using C. neoformans as a model, an airborne opportunistic fungal pathogen that infects mainly immunocompromised but also competent hosts.

Cryptococcus neoformans: Brain Preference, Gender Bias, and Interactions with Mycobacterium tuberculosis and Toxoplasma gondii in HIV-Positive Patients

Cryptococcus neoformans, a high-priority pathogen (WHO, 2022) and ubiquitous fungus, is responsible for hundreds of thousands of meningoencephalitis cases annually, with a high fatality rate. Its distribution is uneven: it primarily affects immunocompromised individuals (especially HIV-positive patients). Our study aims to explore the Cryptococcus' brain tropism in immunosuppressed patients, its gender preference and the possible interactions with other opportunistic neurotropic microorganisms, such as Mycobacterium tuberculosis (MTB) and the brain microbiota, with a particular focus on Toxoplasma gondii (T. gondii).

METHODS

We conducted a retrospective descriptive analysis of all cases diagnosed with central nervous system cryptococcosis (Crypto-CNS) in HIV-positive patients admitted over 10 years (2010-2019) in a tertiary Romanian hospital. We examined their demographic, clinical, immunobiological, and imaging data, as well as their medical history, comorbidities, and coinfections.

RESULTS

Forty-two cases were admitted, with a male predominance (3.6:1) and a mean age of 33.3 years; 24% were diagnosed concomitantly with HIV infection and Crypto-CNS. All patients were severely immunosuppressed, with CD4 counts <200 cells/mm3 (median = 20.5 [1-163], mean = 31.6). Recent/concomitant tuberculosis was found in 10 (27.7%). T. gondii-seropositive patients developed Crypto-CNS at a lower immunological state than seronegative ones (27.1 CD4 cells/mm3 vs. 46.7 cells/mm3, means). Of 25 cases with available brain imagery, 28% had high intracranial pressure. Twelve patients (28.5%) died during the hospitalization within 26.3 days (mean, SD = 21.4); 1-year mortality increased to 50%. In-hospital mortality was associated with lower CD4 counts, increased intracranial pressure, and T. gondii-seropositivity.

CONCLUSIONS

Crypto-CNS in HIV-positive patients mainly affects men and may be promoted by concomitant or recent tuberculosis. T. gondii may confer some protection even at low immune levels but increases mortality when immunity is critically low.

Transcription Factors Fzc9 and Pdr802 Regulate ATP Levels and Metabolism in Cryptococcus neoformans

Transcription factors Fzc9 and Pdr802, characterized by their Zn2Cys6 DNA-binding domain, are essential for the virulence of Cryptococcus neoformans in lung and brain infections. Notably, the in vivo roles of Fzc9 and Pdr802 in contributing to the pathogenicity of C. neoformans are not adequately reflected by the phenotypic characteristics observed in vitro. This study investigates the effects of gene deletion of FZC9 or PDR802 on the proteomic and metabolomic profiles of C. neoformans. Using mass spectrometry analysis, we identified significant changes in protein abundance and metabolite levels, particularly in pathways related to ATP synthesis. These findings deepen our understanding of the metabolic roles of Fzc9 and Pdr802, suggesting potential targets for the development of novel therapeutic strategies against C. neoformans infections.

The curtain model as an alternative and complementary to the classic turgor concept of filamentous fungi

Turgor pressure is critically important for all organisms with the cell wall. In fungi, turgor is involved in the apical growth of hyphae, affects cell size, provides tension to the plasma membrane, creates the necessary rigidity for hyphae to penetrate the substrate, and has many other functions. However, there is increasing evidence that turgor pressure is not always the sole or main factor influencing some of these processes. This review characterizes the curtain model, previously proposed to describe the regulation of plasma membrane tension in the hyphae of basidiomycetes. The current understanding of the four main components of the model is outlined: the driving actin cytoskeleton, the elastic cell wall, tight adhesion of the plasma membrane to the cell wall, and macroinvaginations of the plasma membrane. All four elements, as a single model, complement or replace some physiological functions of turgor and allow us to understand how a non-apical fungal cell maintains its physiological functionality under changing environmental conditions. Further experimental confirmation of this model is fundamentally important for mycology and applied sciences.

Bio-orthogonal Labeling of Chitin in Native Pathogenic Candida Species via the Chitin Scavenge Pathway

The fungal cell wall is essential for the integrity of the cell, providing strength and shape, as well as protection against environmental stimuli. For pathogenic fungi, the cell wall is also the initial point of contact with the host. Specific cell wall features such as hypha tails and smaller glycan components modulate a wide range of fungal interactions with the immune defenses. Here, a bio-orthogonal labeling method utilizing N-acetyl-glucosamine (NAG) probes is developed to fluorescently label native, pathogenic yeast via the chitin scavenging pathway. A panel of NAG probes was assembled, synthesized, and characterized for the ability to label the chitin in pathogenic yeast. Enzymatic data show that the native scavenging biosynthetic enzyme, Hxk1, is promiscuous, permitting the labeling of the native chitin biopolymer. This chitin labeling method was validated via the development of mass spectrometry protocols. When compared to the current available labeling systems for chitin, the probes do not affect the integrity of the cell wall and do not interrupt cell growth. Furthermore, the NAG probes enabled multiple "click" platforms across pathogenic Candida species including Candida albicans and Candida tropicalis. Budding and filamentous hyphal states were observed. The results indicate the probes' utility for in vivo study of the morphological, pathogenic switch, and visualization of growth patterns. Thus, the use of these probes in pathogenic Candida strains is ideal for a variety of future applications including strain specific antifungals, diagnostic tools, and immunomodulators.

The antimicrobial activity of ETD151 defensin is dictated by the presence of glycosphingolipids in the targeted organisms

Fungal infections represent a significant global health concern, with a growing prevalence of antifungal drug resistance. Targeting glucosylceramides (GlcCer), which are functionally important glycosphingolipids (GSL) present in fungal membranes, represents a promising strategy for the development of antifungal drugs. GlcCer are associated with the antifungal activity of certain plant and insect defensins. The 44-residue ETD151 peptide, optimized from butterfly defensins, is active against several fungal pathogens. ETD151 has been shown to induce a multifaceted mechanism of action (MOA) in Botrytis cinerea, a multiresistant phytopathogenic fungus. However, the target has yet to be identified. Our findings demonstrate that the presence of GlcCer in membranes determines the susceptibility of Pichia pastoris and Candida albicans toward ETD151. To ascertain whether this is due to direct molecular recognition, we demonstrate that ETD151 selectively recognizes liposomes containing GlcCer from B. cinerea, which reveals a methylated-sphingoid base structure. The dissociation constant was estimated by microscale thermophoresis to be in the µM range. Finally, fluorescence microscopy revealed that ETD151 localizes preferentially at the surface of B. cinerea. Furthermore, the majority of prokaryotic cells do not contain GSL, which explains their resistance to ETD151. We investigated the susceptibility of Novosphingobium capsulatum, one of the rare GSL-containing bacteria, to ETD151. ETD151 demonstrated transient morphological changes and inhibitory growth activity (IC50 ~75 µM) with an affinity for the cell surface, emphasizing the critical importance of GSL as target. Understanding the MOA of ETD151 could pave the way for new perspectives in human health and crop protection.

Biogenic selenium nanoparticles: a comprehensive update on the multifaceted application, stability, biocompatibility, risk, and opportunity

Biogenic selenium nanoparticles (SeNPs) have emerged as promising area of research due to their unique properties and potential multifaceted applications. The biosynthesis of SeNPs through biological methods, such as using microorganism, plant extracts, etc., offers a safe, eco-friendly, and biocompatible approach, compared to traditional chemical synthesis. Recent several studies demonstrated that multifaceted application of SeNPs includes a broad area such as antibacterial, anticancer, antioxidant, antiviral, anti-inflammatory, antidiabetic, and excellent wound healing activity. On the other hand, SeNPs have also shown promising application in sensing of inorganic toxic metals, electrochemistry, agro-industries, aqua-cultures, and in fabrication of solar panels. Additionally, SeNPs capability to enhance the efficacy of traditional antibiotics and act as effective agents against multidrug-resistant pathogens has shown their potential in addressing critical health challenges. Although, the SeNPs exhibit wide applicability, the potential toxicity of Se, particularly in its various oxidative states, necessitates careful assessment of the environmental and health impacts associated with their use. Therefore, understanding the balance between their beneficial properties and potential risks is crucial for its safe applications. This review focuses exclusively on SeNPs synthesized via eco-friendly process, excluding research utilizing other synthesis processes. Moreover, this review aims to offer an overview of the diverse applications, potential risks, stability requirement, and cytocompatibility requirement, and multifaceted opportunities associated with SeNPs. Ultimately, the review bridges a gap in knowledge by providing an updated details of multifaceted applications of SeNPs.

Graveyard effects of antimicrobial nanostructured titanium over prolonged exposure to drug resistant bacteria and fungi

Innovations in nanostructured surfaces have found a practical place in the medical area with use in implant materials for post-operative infection prevention. These textured surfaces should be dual purpose: (1) bactericidal on contact and (2) resistant to biofilm formation over prolonged periods. Here, hydrothermally etched titanium surfaces were tested against two highly antimicrobial resistant microbial species, methicillin-resistant Staphylococcus aureus and Candida albicans. Two surface types - unmodified titanium and nanostructured titanium - were incubated in a suspension of each microbial strain for 1 day and 7 days. Surface topography and cross-sectional information of the microbial cells adhered to the surfaces, along with biomass volume and live/dead rate, showed that while nanostructured titanium was able to kill microbes after 1 day of exposure, after 7 days, the rate of death becomes negligible when compared to the unmodified titanium. This suggests that as biofilms mature on a nanostructured surface, the cells that have lysed conceal the nanostructures and prime the surface for planktonic cells to adhere, decreasing the possibility of structure-induced lysis. Synchrotron macro-attenuated total reflection Fourier transform infrared (macro ATR-FTIR) micro-spectroscopy was used to elucidate the biochemical changes occurring following exposure to differing surface texture and incubation duration, providing further understanding into the effects of surface morphology on the biochemical molecules (lipids, proteins and polysaccharides) in an evolving and growing microbial colony.

Anti-Mold Activities of Cationic Oligomeric Surfactants

Molds are persistent and harmful but receive far less research attention compared with pathogenic bacteria. With the increase in microbial resistance to single-chain surfactant antimicrobial agents, it is crucial to investigate how surfactant structures affect the antimicrobial activity of surfactants. Here, we have studied the antimold efficacy of a series of oligomeric cationic quaternary ammonium surfactants at varying oligomerization levels with or without dynamic covalent imine bonds. Four common molds are chosen as representatives: A. niger, T. viride, C. globosum, and P. funiculosum. The minimum fungicidal concentration (MFC) results indicate that the dynamic covalent surfactants in solution display stronger antimold activity than the surfactants of the same oligomerization degree without imine bonds, and the antimold activity decreases as the oligomerization degree increases. The superior fungicidal efficacy of imine-based surfactants in solution is attributed to their longer hydrophobic chains and benzene rings, which enhance the interactions with mold membranes, causing perforation and membrane disruption. Nonetheless, the higher oligomerization degree reduces antimold effectiveness due to the formation of overly stable aggregates, which lower the concentration of free molecular monomers released from aggregates and may accumulate on mold spore membranes. However, on fabric surfaces, the surfactants with a higher oligomerization degree show stronger antimold performance. The multiple hydrophobic chains and cationic headgroups result in greater surfactant adsorption and stronger antimildew activity. Moreover, the reversibility of the imine-based surfactants plays a significant role in reducing the likelihood of resistance. This work is helpful to construct antimicrobial agents with broad-spectrum activity and a weak resistance potential.