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

Peanut Rhizosphere Achromobacter xylosoxidans Inhibits Aspergillus flavus Development and Aflatoxin Synthesis by Inducing Apoptosis through Targeting the Cell Membrane

Contamination of crop seeds and feed with Aspergillus flavus and its associated aflatoxins presents a significant threat to human and animal health due to their hepatotoxic and carcinogenic properties. To address this challenge, researchers have screened for potential biological control agents in peanut soil and pods. This study identified a promising candidate, a strain of the nonpigmented bacterium, Achromobacter xylosoxidans ZJS2-1, isolated from the peanut rhizosphere in Zhejiang Province, China, exhibiting notable antifungal and antiaflatoxin activities. Further investigations demonstrated that ZJS2-1 active substances (ZAS) effectively inhibited growth at a MIC of 60 μL/mL and nearly suppressed AFB1 production by 99%. Metabolomic analysis revealed that ZAS significantly affected metabolites involved in cell wall and membrane biosynthesis, leading to compromised cellular integrity and induced apoptosis in A. flavus through the release of cytochrome c. Notably, ZAS targeted SrbA, a key transcription factor involved in ergosterol biosynthesis and cell membrane integrity, highlighting its crucial role in ZJS2-1's biocontrol mechanism. Moreover, infection of crop seeds and plant wilt caused by A. flavus can be efficiently alleviated by ZAS. Additionally, ZJS2-1 and ZAS demonstrated significant inhibitory effects on various Aspergillus species, with inhibition rates ranging from 80 to 99%. These findings highlight the potential of ZJS2-1 as a biocontrol agent against Aspergillus species, offering a promising solution to enhance food safety and protect human health.

A comparative cell wall analysis of Trichoderma spp. confirms a conserved polysaccharide scaffold and suggests an important role for chitosan in mycoparasitism

Fungal cell walls are dynamic extracellular matrices that enable efficient adaptation to changing environments. While the cell wall compositions of yeasts, human, and plant pathogenic fungi have been studied to some extent, the cell walls of mycoparasites remain poorly characterized. Trichoderma species comprise a diverse group of soil fungi with different survival strategies and lifestyles. The comparative study of cell wall carbohydrate-active enzymes in 13 Trichoderma spp. revealed that the types of enzymes involved in chitin and chitosan metabolism are phylogenetically distant between mycoparasitic and saprotrophic species. Here, we compare the carbohydrate composition and function of the cell wall of a saprotrophic strain Trichoderma reesei with that of the mycoparasitic, biological control agent Trichoderma atroviride. Monosaccharide and glycosidic linkage analyses as well as dual in situ interaction assays showed that the cell wall polysaccharide composition is conserved between both species, except for the amounts of chitin detected. The results suggest that the observed accumulation of chitosan during mycoparasitism may prevent host recognition. Remarkably, Trichoderma atroviride undergoes dynamic cell wall adaptations during both vegetative development and mycoparasitism, which appears to be confirmed by an evolutionarily expanded group of specialized enzymes. Overall, our analyses support the notion that habitat specialization is reflected in cell wall architecture and that plastic chitin remodeling may confer an advantage to mycoparasites, ultimately enabling the successful invasion and parasitism of plant pathogens. This information may potentially be exploited for the control of crop diseases using biological agents.

IMPORTANCE

Trichoderma species are emerging model fungi for the development of biocontrol agents and are used in industrial biotechnology as efficient enzyme producers. Fungal cell walls are complex structures that differ in carbohydrate, protein, and enzyme composition across taxa. Here, we present a chemical characterization of the cell walls of two Trichoderma spp., namely the predominantly saprotrophic Trichoderma reesei and the mycoparasite Trichoderma atroviride. Chemical profiling revealed that Trichoderma spp. remodel their cell wall to adapt to particular lifestyles, with dynamic changes during vegetative development. Importantly, we found that chitosan accumulation during mycoparasitism of a fungal host emerged as a sophisticated strategy underpinning an effective attack. These insights shed light on the molecular mechanisms that allow mycoparasites to overcome host defenses and can be exploited to improve the application of T. atroviride in biological pest control. Moreover, our results provide valuable information for targeting the fungal cell wall for therapeutic purposes.

Unveiling the structural properties and induced resistance activity in rice of Chitin/Chitosan-Glucan Complex of Rhizoctonia solani AG1 IA inner cell wall

Phytopathogen cell wall polysaccharides have important physiological functions. In this study, we isolated and characterized the alkali-insoluble residue on the inner layers of the Rhizoctonia solani AG1 IA cell wall (RsCW-AIR). Through chemical composition and structural analysis, RsCW-AIR was mainly identified as a complex of chitin/chitosan and glucan (ChCsGC), with glucose and glucosamine were present in a molar ratio of 2.7:1.0. The predominant glycosidic bond linkage of glucan in ChCsGC was β-1,3-linked Glcp, both the α and β-polymorphic forms of chitin were presented in it by IR, XRD, and solid-state NMR, and the ChCsGC exhibited a degree of deacetylation measuring 67.08 %. RsCW-AIR pretreatment effectively reduced the incidence of rice sheath blight, and its induced resistance activity in rice was evaluated, such as inducing a reactive oxygen species (ROS) burst, leading to the accumulation of salicylic acid (SA) and the up-regulation of SA-related gene expression. The recognition of RsCW-AIR in rice is partially dependent on CERK1.

Tyrosol-gold nanoparticle functionalized acacia gum-PVA nanofibers for mitigation of Candida biofilm

Increasing incidences of fungal infections and prevailing antifungal resistance in healthcare settings has given rise to an antifungal crisis on a global scale. The members of the genus Candida, owing to their ability to acquire sessile growth, are primarily associated with superficial to invasive fungal infections, including the implant-associated infections. The present study introduces a novel approach to combat the sessile/biofilm growth of Candida by fabricating nanofibers using a nanoencapsulation approach. This technique involves the synthesis of tyrosol (TYS) functionalized chitosan gold nanocomposite, which is then encapsulated into PVA/AG polymeric matrix using electrospinning. The FESEM, FTIR analysis of prepared TYS-AuNP@PVA/AG NF suggested the successful encapsulation of TYS into the nanofibers. Further, the sustained and long-term stability of TYS in the medium was confirmed by drug release and storage stability studies. The prepared nanomats can absorb the fluid, as evidenced by the swelling index of the nanofibers. The growth and biofilm inhibition, as well as the disintegration studies against Candida, showed 60-70 % biofilm disintegration when 10 mg of TYS-AuNP@PVA/AG NF was used, hence confirming its biological effectiveness. Subsequently, the nanofibers considerably reduced the hydrophobicity index and ergosterol content of the treated cells. Considering the challenges associated with the inhibition/disruption of fungal biofilm, the fabricated nanofibers prove their effectiveness against Candida biofilm. Therefore, nanocomposite-loaded nanofibers have emerged as potential materials that can control fungal colonization and could also promote healing.

Row1, a member of a new family of conserved fungal proteins involved in infection, is required for appressoria functionality in Ustilago maydis

The appressorium of phytopathogenic fungi is a specific structure with a crucial role in plant cuticle penetration. Pathogens with melanized appressoria break the cuticle through cell wall melanization and intracellular turgor pressure. However, in fungi with nonmelanized appressorium, the mechanisms governing cuticle penetration are poorly understood. Here we characterize Row1, a previously uncharacterized appressoria-specific protein of Ustilago maydis that localizes to membrane and secretory vesicles. Deletion of row1 decreases appressoria formation and plant penetration, thereby reducing virulence. Specifically, the Δrow1 mutant has a thicker cell wall that is more resistant to glucanase degradation. We also observed that the Δrow1 mutant has secretion defects. We show that Row1 is functionally conserved at least among Ustilaginaceae and belongs to the Row family, which consists of five other proteins that are highly conserved among Basidiomycota fungi and are involved in U. maydis virulence. We observed similarities in localization between Row1 and Row2, which is also involved in cell wall remodelling and secretion, suggesting similar molecular functions for members of this protein family. Our data suggest that Row1 could modify the chitin-glucan matrix of the fungal cell wall and may be involved in unconventional protein secretion, thereby promoting both appressoria maturation and penetration.

Adaptative survival of Aspergillus fumigatus to echinocandins arises from cell wall remodeling beyond β-1,3-glucan synthesis inhibition

Antifungal echinocandins inhibit the biosynthesis of β-1,3-glucan, a major and essential polysaccharide component of the fungal cell wall. However, the efficacy of echinocandins against the pathogen Aspergillus fumigatus is limited. Here, we use solid-state nuclear magnetic resonance (ssNMR) and other techniques to show that echinocandins induce dynamic changes in the assembly of mobile and rigid polymers within the A. fumigatus cell wall. The reduction of β-1,3-glucan induced by echinocandins is accompanied by a concurrent increase in levels of chitin, chitosan, and highly polymorphic α-1,3-glucans, whose physical association with chitin maintains cell wall integrity and modulates water permeability. The rearrangement of the macromolecular network is dynamic and controls the permeability and circulation of the drug throughout the cell wall. Thus, our results indicate that echinocandin treatment triggers compensatory rearrangements in the cell wall that may help A. fumigatus to tolerate the drugs' antifungal effects.

The sunflower jacalin Helja: biological and structural insights of its antifungal activity against Candida albicans

The limited availability of efficient treatments for Candida infections and the increased emergence of antifungal-resistant strains stimulates the search for new antifungal agents. We have previously isolated a sunflower mannose-binding lectin (Helja) with antifungal activity against Candida albicans, capable of binding mannose-bearing oligosaccharides exposed on the cell surface. This work aimed to investigate the biological and biophysical basis of Helja's binding to C. albicans cell wall mannans and its influence on the fungicidal activity of the lectin. We evaluated the interaction of Helja with the cell wall mannans extracted from the isogenic parental strain (WT) and a glycosylation-defective C. albicans with altered cell wall phosphomannosylation (mnn4∆ null mutants) and investigated its antifungal effect. Helja exhibited stronger antifungal activity on the mutant strain, showing greater inhibition of fungal growth, loss of cell viability, morphological alteration, and formation of clusters with agglutinated cells. This differential biological activity of Helja was correlated with the biophysical parameters determined by solid phase assays and isothermal titration calorimetry, which demonstrated that the lectin established stronger interactions with the cell wall mannans of the mnn4∆ null mutant than with the WT strain. In conclusion, our results provide new evidence on the nature of the Helja molecular interactions with cell wall components, i.e. phosphomannan, and its impact on the antifungal activity. This study highlights the relevance of plant lectins in the design of effective antifungal therapies.

Bioinformatics-Driven mRNA-Based Vaccine Design for Controlling Tinea Cruris Induced by Trichophyton rubrum

Tinea cruris, a dermatophyte fungal infection predominantly caused by Trichophyton rubrum and Epidermophyton floccosum, primarily affects the groin, pubic region, and adjacent thigh. Its recurrence is frequent, attributable to repeated fungal infections in susceptible individuals, especially those with onychomycosis or tinea pedis, which act as reservoirs for dermatophytes. Given the persistent nature of tinea cruris, vaccination emerges as a promising strategy for fungal infection management, offering targeted, durable protection against various fungal species. Vaccines stimulate both humoral and cell-mediated immunity and are administered prophylactically to prevent infections while minimizing the risk of antifungal resistance development. Developing fungal vaccines is challenging due to the thick fungal cell wall, similarities between fungal and human cells, antigenic variation, and evolutionary resemblance to animals, complicating non-toxic target identification and T-cell response variability. No prior research has shown an mRNA vaccine for T. rubrum. Hence, this study proposes a novel mRNA-based vaccine for tinea cruris, potentially offering long-term immunity and reducing reliance on antifungal medications. This study explores the complete proteome of T. rubrum, identifying potential protein candidates for vaccine development through reverse vaccinology. Immunogenic epitopes from these candidates were mapped and integrated into multitope vaccines and reverse translated to construct mRNA vaccines. Then, the mRNA was translated and computationally assessed for physicochemical, chemical, and immunological attributes. Notably, 1,3-beta-glucanosyltransferase, CFEM domain-containing protein, cell wall galactomannoprotein, and LysM domain-containing protein emerged as promising vaccine targets. Antigenic, immunogenic, non-toxic, and non-allergenic cytotoxic T lymphocyte, helper T lymphocyte, and B lymphocyte epitopes were selected and linked with appropriate linkers and Toll-like receptor (TLR) agonist adjuvants to formulate vaccine candidates targeting T. rubrum. The protein-based vaccines underwent reverse translation to construct the mRNA vaccines, which, after inoculation, were translated again by host ribosomes to work as potential components for triggering the immune response. After that, molecular docking, normal mode analysis, and molecular dynamic simulation confirmed strong binding affinities and stable complexes between vaccines and TLR receptors. Furthermore, immune simulations of vaccines with and without adjuvant demonstrated activation of immune responses, evidenced by elevated levels of IgG1, IgG2, IgM antibodies, cytokines, and interleukins. There was no significant change in antibody production between vaccines with and without adjuvants, but adjuvants are crucial for activating the innate immune response via TLRs. Although mRNA vaccines hold promise against fungal infections, further research is essential to assess their safety and efficacy. Experimental validation is crucial for evaluating their immunogenicity, effectiveness, and safety.

Surface-Charge Tuned Polymeric Nanoemulsions for Carvacrol Delivery in Interkingdom Biofilms

Biofilms, intricate microbial communities entrenched in extracellular polymeric substance (EPS) matrices, pose formidable challenges in infectious disease treatment, especially in the context of interkingdom biofilms prevalent in the oral environment. This study investigates the potential of carvacrol-loaded biodegradable nanoemulsions (NEs) with systematically varied surface charges─cationic guanidinium (GMT-NE) and anionic carboxylate (CMT-NE). Zeta potentials of +25 mV (GMT-NE) and -33 mV (CMT-NE) underscore successful nanoemulsion fabrication (∼250 nm). Fluorescent labeling and dynamic tracking across three dimensions expose GMT-NE's superior diffusion into oral biofilms, yielding a robust antimicrobial effect with 99.99% killing for both streptococcal and Candida species and marked reductions in bacterial cell viability compared to CMT-NE (∼4-log reduction). Oral mucosa tissue cultures affirm the biocompatibility of both NEs with no morphological or structural changes, showcasing their potential for combating intractable biofilm infections in oral environment. This study advances our understanding of NE surface charges and their interactions within interkingdom biofilms, providing insights crucial for addressing complex infections involving bacteria and fungi in the demanding oral context.

All hands on Dec: Treating cryptococcosis with dectin decorated liposomes loaded with antifungals

Systemic cryptococcosis is often fatal even with the current antifungal therapy and there is no vaccine available. Induction therapy with amphotericin B (AmB) is essential for its treatment, which can be either in the form of AmB deoxycholate at 1 mg/kg/day for 7 days or a single dose of liposomal AmB (AmB-LLs) at 10 mg/kg, both in combination with flucytosine. AmB is highly toxic and it is imperative to further increase its efficacy without increasing its toxicity. Previously, we developed a targeted antifungal drug delivery system (DectiSome) that uses liposomes decorated with host-pathogen receptor dectins to target AmB to fungal cells. Here, we showed that a single dose of Dectin-2 coated liposomal AmB, relative to AmB-LLs, reduced fungal burden and prolonged animal survival in the murine model of systemic cryptococcosis. Our results demonstrate that DectiSomes are a promising antifungal delivery system that could improve cryptococcosis therapy in the future.

Smart proteins as a new paradigm for meeting dietary protein sufficiency of India: a critical review on the safety and sustainability of different protein sources

India, a global leader in agriculture, faces sustainability challenges in feeding its population. Although primarily a vegetarian population, the consumption of animal derived proteins has tremendously increased in recent years. Excessive dependency on animal proteins is not environmentally sustainable, necessitating the identification of alternative smart proteins. Smart proteins are environmentally benign and mimic the properties of animal proteins (dairy, egg and meat) and are derived from plant proteins, microbial fermentation, insects and cell culture meat (CCM) processes. This review critically evaluates the technological, safety, and sustainability challenges involved in production of smart proteins and their consumer acceptance from Indian context. Under current circumstances, plant-based proteins are most favorable; however, limited land availability and impending climate change makes them unsustainable in the long run. CCM is unaffordable with high input costs limiting its commercialization in near future. Microbial-derived proteins could be the most sustainable option for future owing to higher productivity and ability to grow on low-cost substrates. A circular economy approach integrating agri-horti waste valorization and C1 substrate synthesis with microbial biomass production offer economic viability. Considering the use of novel additives and processing techniques, evaluation of safety, allergenicity, and bioavailability of smart protein products is necessary before large-scale adoption.

Rapid Classification and Differentiation of Sepsis-Related Pathogens Using FT-IR Spectroscopy

Sepsis is a life-threatening condition arising from a dysregulated host immune response to infection, leading to a substantial global health burden. The accurate identification of bacterial pathogens in sepsis is essential for guiding effective antimicrobial therapy and optimising patient outcomes. Traditional culture-based bacterial typing methods present inherent limitations, necessitating the exploration of alternative diagnostic approaches. This study reports the successful application of Fourier-transform infrared (FT-IR) spectroscopy in combination with chemometrics as a potent tool for the classification and discrimination of microbial species and strains, primarily sourced from individuals with invasive infections. These samples were obtained from various children with suspected sepsis infections with bacteria and fungi originating at different sites. We conducted a comprehensive analysis utilising 212 isolates from 14 distinct genera, comprising 202 bacterial and 10 fungal isolates. With the spectral analysis taking several weeks, we present the incorporation of quality control samples to mitigate potential variations that may arise between different sample plates, especially when dealing with a large sample size. The results demonstrated a remarkable consistency in clustering patterns among 14 genera when subjected to principal component analysis (PCA). Particularly, Candida, a fungal genus, was distinctly recovered away from bacterial samples. Principal component discriminant function analysis (PC-DFA) allowed for distinct discrimination between different bacterial groups, particularly Gram-negative and Gram-positive bacteria. Clear differentiation was also observed between coagulase-negative staphylococci (CNS) and Staphylococcus aureus isolates, while methicillin-resistant S. aureus (MRSA) was also separated from methicillin-susceptible S. aureus (MSSA) isolates. Furthermore, highly accurate discrimination was achieved between Enterococcus and vancomycin-resistant enterococci isolates with 98.4% accuracy using partial least squares-discriminant analysis. The study also demonstrates the specificity of FT-IR, as it effectively discriminates between individual isolates of Streptococcus and Candida at their respective species levels. The findings of this study establish a strong groundwork for the broader implementation of FT-IR and chemometrics in clinical and microbiological applications. The potential of these techniques for enhanced microbial classification holds significant promise in the diagnosis and management of invasive bacterial infections, thereby contributing to improved patient outcomes.

Near-infrared spectroscopy and multivariate analysis as effective, fast, and cost-effective methods to discriminate Candida auris from Candida haemulonii

Candida auris and Candida haemulonii are two emerging opportunistic pathogens that have caused an increase in clinical cases in the recent years worldwide. The differentiation of some Candida species is highly laborious, difficult, costly, and time-consuming depending on the similarity between the species. Thus, this study aimed to develop a new, faster, and less expensive methodology for differentiating between C. auris and C. haemulonii based on near-infrared (NIR) spectroscopy and multivariate analysis. C. auris CBS10913 and C. haemulonii CH02 were separated in 15 plates per species, and three isolated colonies of each plate were selected for Fourier transform near-infrared (FT-NIR) analysis, totaling 90 spectra. Subsequently, principal component analysis (PCA) and variable selection algorithms, including the successive projections algorithm (SPA) and genetic algorithm (GA) coupled with linear discriminant analysis (LDA), were employed to discern distinctive patterns among the samples. The use of PCA, SPA, and GA algorithms associated with LDA achieved 100% sensitivity and specificity for the discriminations. The SPA-LDA and GA-LDA algorithms were essential in selecting the variables (infrared wavelengths) of most importance for the models, which could be attributed to binding of cell wall structures such as polysaccharides, peptides, proteins, or molecules resulting from yeasts' metabolism. These results show the high potential of combined FT-NIR and multivariate analysis techniques for the classification of Candida-like fungi, which can contribute to faster and more effective diagnosis and treatment of patients affected by these microorganisms.

Polyphasic identification of Rhizopus oryzae and evaluation of physical fermentation parameters in potato starch processing liquid waste for β-glucan production

Β-glucans are polysaccharide macromolecules that can be found in the cell walls of molds, such as Rhizopus oryzae. They provide functional properties in food systems and have immunomodulatory activity, anticancer, and prebiotic effects; reduce triglycerides and cholesterol; and prevent obesity, among others benefits. Furthermore, potato starch production requires a large amount of water, which is usually discharged into the environment, creating problems in soils and bodies of water. The physical parameters to produce β-glucans were determined, liquid waste from potato starch processing was used and native Rhizopus oryzae was isolated and identified from cereal grains. The isolates grew quickly on the three types of agars used at 25 °C and 37 °C, and they did not grow at 45 °C. Rhizopus oryzae M10A1 produced the greatest amount of β-glucans after six days of culture at 30 °C, pH 6, a stirring rate of 150 rpm and a fermentation volume of 250 mL. By establishing the physical fermentation parameters and utilizing the liquid waste from potato starch, Rhizopus oryzae M10A1 yielded 397.50 mg/100 g of β-glucan was obtained.

The MYB-like protein MylA contributes to conidiogenesis and conidial germination in Aspergillus nidulans

Myeloblastosis (MYB)-like proteins are a family of highly conserved transcription factors in animals, plants, and fungi and are involved in the regulation of mRNA expression of genes. In this study, we identified and characterized one MYB-like protein in the model organism Aspergillus nidulans. We screened the mRNA levels of genes encoding MYB-like proteins containing two MYB repeats in conidia and found that the mRNA levels of four genes including flbD, cicD, and two uncharacterized genes, were high in conidia. To investigate the roles of two uncharacterized genes, AN4618 and AN10944, deletion mutants for each gene were generated. Our results revealed that AN4618 was required for fungal development. Therefore, we further investigated the role of AN4618, named as mylA, encoding the MYB-like protein containing two MYB repeats. Functional studies revealed that MylA was essential for normal fungal growth and development. Phenotypic and transcriptomic analyses demonstrated that deletion of mylA affected stress tolerance, cell wall integrity, and long-term viability in A. nidulans conidia. In addition, the germination rate of the mylA deletion mutant conidia was decreased compared with that of the wild-type conidia. Overall, this study suggests that MylA is critical for appropriate development, conidial maturation, dormancy, and germination in A. nidulans.

Rhein Inhibits Cell Development and Aflatoxin Biosynthesis via Energy Supply Disruption and ROS Accumulation in Aspergillus flavus

Aspergillus flavus and its carcinogenic secondary metabolites, aflatoxins, not only cause serious losses in the agricultural economy, but also endanger human health. Rhein, a compound extracted from the Chinese herbal medicine Rheum palmatum L. (Dahuang), exhibits good anti-inflammatory, anti-tumor, and anti-oxidative effects. However, its effect and underlying mechanisms against Aspergillus flavus have not yet been fully illustrated. In this study, we characterized the inhibition effect of rhein on A. flavus mycelial growth, sporulation, and aflatoxin B1 (AFB1) biosynthesis and the potential mechanism using RNA-seq analysis. The results indicate that A. flavus mycelial growth and AFB1 biosynthesis were significantly inhibited by 50 μM rhein, with a 43.83% reduction in colony diameter and 87.2% reduction in AFB1 production. The RNA-seq findings demonstrated that the differentially expressed genes primarily participated in processes such as spore formation and development, the maintenance of cell wall and membrane integrity, management of oxidative stress, the regulation of the citric acid cycle, and the biosynthesis of aflatoxin. Biochemical verification experiments further confirmed that 50 μM rhein effectively disrupted cell wall and membrane integrity and caused mitochondrial dysfunction through disrupting energy metabolism pathways, leading to decreased ATP synthesis and ROS accumulation, resulting in impaired aflatoxin biosynthesis. In addition, a pathogenicity test showed that 50 μM rhein inhibited A. flavus spore growth in peanut and maize seeds by 34.1% and 90.4%, while AFB1 biosynthesis was inhibited by 60.52% and 99.43%, respectively. In conclusion, this research expands the knowledge regarding the antifungal activity of rhein and provides a new strategy to mitigate A. flavus contamination.

Antifungal resistance: why are we losing this battle?

The emergence of fungal pathogens and changes in the epidemiological landscape are prevalent issues in clinical mycology. Reports of resistance to antifungals have been reported. This review aims to evaluate molecular and nonmolecular mechanisms related to antifungal resistance. Mutations in the ERG genes and overexpression of the efflux pump (MDR1, CDR1 and CDR2 genes) were the most reported molecular mechanisms of resistance in clinical isolates, mainly related to Azoles. For echinocandins, a molecular mechanism described was mutation in the FSK genes. Furthermore, nonmolecular virulence factors contributed to therapeutic failure, such as biofilm formation and selective pressure due to previous exposure to antifungals. Thus, there are many public health challenges in treating fungal infections.

Terpinen-4-ol from tea tree oil prevents Aspergillus flavus growth in postharvest wheat grain

Plant volatile organic compounds (PVOCs) have gained increasing attention for their role in preventing fungal spoilage and insect contamination in postharvest agro-products owing to their effectiveness and sustainability. In this study, the essential oil was extracted from fresh M. alternifolia (tea tree) leaves, and the fumigation vapor of tea tree oil (TTO) completely inhibited the growth of Aspergillus flavus on agar plates at a concentration of 1.714 μL/mL. Terpinen-4-ol was identified as the major component (40.76 %) of TTO volatiles analyzed using headspace gas chromatography-mass spectrometry. Terpinen-4-ol vapor completely inhibited the A. flavus growth on agar plates and 20 % moisture wheat grain at 0.556 and 1.579 μL/mL, respectively, indicating that terpinen-4-ol serves as the main antifungal constituent in TTO volatiles. The minimum inhibitory concentration of terpinen-4-ol in liquid-contact culture was 1.6 μL/mL. Terpinen-4-ol treatment caused depressed, wrinkled, and punctured mycelial morphology and destroyed the plasma membrane integrity of A. flavus. Metabolomics analysis identified significant alterations in 93 metabolites, with 79 upregulated and 14 downregulated in A. flavus mycelia exposed to 1.6 μL/mL terpinen-4-ol for 6 h, involved in multiple cellular processes including cell membrane permeability and integrity, the ABC transport system, pentose phosphate pathway, and the tricarboxylic acid cycle. Biochemical analysis and 2,7-dichlorofluorescein diacetate staining showed that terpinen-4-ol induced oxidative stress and mitochondrial dysfunction in A. flavus mycelia. This study provides new insights into the antifungal effects of the main TTO volatile compounds terpinen-4-ol on the growth of A. flavus.

A commensal-derived sugar protects against metabolic disease

Obesity is a worsening global epidemic that is regulated by the microbiota through unknown bacterial factors. We discovered a human-derived commensal bacterium, Clostridium immunis , that protects against metabolic disease by secreting a phosphocholine-modified exopolysaccharide. Genetic interruption of the phosphocholine biosynthesis locus ( licABC ) results in a functionally inactive exopolysaccharide, which demonstrates the critical requirement for this phosphocholine moiety. This C. immunis exopolysaccharide acts via group 3 innate lymphoid cells and modulating IL-22 levels, which results in a reduction in serum triglycerides, body weight, and visceral adiposity. Importantly, phosphocholine biosynthesis genes are less abundant in humans with obesity or hypertriglyceridemia, findings that suggest the role of bacterial phosphocholine is conserved across mice and humans. These results define a bacterial molecule-and its key structural motif-that regulates host metabolism. More broadly, they highlight how small molecules, such as phosphocholine, may help fine-tune microbiome- immune-metabolism interactions.

Identification of Yeast and Yeast-Like Fungi at a Tertiary Care Center: A Retrospective Study

Background Fungal infections pose a significant global health challenge. Despite their substantial impact, these ubiquitous fungi can become pathogenic but have not received adequate attention in public health, leading to infections that are often underestimated by the general public and healthcare professionals. Candida species and Cryptococcus species play a key role in these infections, with emerging multidrug resistance in Candida species posing considerable challenges. This study aimed to understand the prevalence of yeast and yeast-like infections, particularly in the COVID-19 era, and to assess the antifungal susceptibility pattern. Methodology A retrospective observational study was conducted at a rural tertiary care medical college in Maharashtra, India. Retrospective records of samples processed for fungal culture were analyzed in the microbiology department. Yeast identification and antifungal susceptibility were performed using the VITEK-2 automated system. Results Among 95 fungal isolates, 86 (90.52%) were yeast isolates, primarily non-albicans Candida (NAC) species. Candida albicans accounted for 41 (47.67%) yeast isolates. In 14 isolates, NAC species were not identified by the VITEK-2 system up to the species level. Isolates from urine samples contributed the highest percentage of 61% (58) of yeast isolates. C. albicans showed high sensitivity to most antifungal agents. Other Candida species, such as Candida famata, Candida parapsilosis, and Candida guilliermondii, were sensitive to all antifungal agents. Candida auris showed complete resistance to amphotericin B and fluconazole but sensitivity to other agents. Mixed sensitivity patterns were observed in Candida ciferri and Candida lusitaniae, with some resistance to voriconazole, caspofungin, and micafungin. Conclusions This study shows the increasing prevalence of yeast and yeast-like infections, particularly NAC, during the COVID-19 era. Improved yeast identification and susceptibility testing are crucial for guiding the appropriate treatment and mitigating the impact of these infections, emphasizing the need for comprehensive future studies in this area.

Cell envelope and stress-responsive pathways underlie an evolved oleaginous Rhodotorula toruloides strain multi-stress tolerance

BACKGROUND

The red oleaginous yeast Rhodotorula toruloides is a promising cell factory to produce microbial oils and carotenoids from lignocellulosic hydrolysates (LCH). A multi-stress tolerant strain towards four major inhibitory compounds present in LCH and methanol, was derived in our laboratory from strain IST536 (PYCC 5615) through adaptive laboratory evolution (ALE) under methanol and high glycerol selective pressure.

RESULTS

Comparative genomic analysis suggested the reduction of the original strain ploidy from triploid to diploid, the occurrence of 21,489 mutations, and 242 genes displaying copy number variants in the evolved strain. Transcriptomic analysis identified 634 genes with altered transcript levels (465 up, 178 down) in the multi-stress tolerant strain. Genes associated with cell surface biogenesis, integrity, and remodelling and involved in stress-responsive pathways exhibit the most substantial alterations at the genome and transcriptome levels. Guided by the suggested stress responses, the multi-stress tolerance phenotype was extended to osmotic, salt, ethanol, oxidative, genotoxic, and medium-chain fatty acid-induced stresses.

CONCLUSIONS

The comprehensive analysis of this evolved strain provided the opportunity to get mechanistic insights into the acquisition of multi-stress tolerance and a list of promising genes, pathways, and regulatory networks, as targets for synthetic biology approaches applied to promising cell factories, toward more robust and superior industrial strains. This study lays the foundations for understanding the mechanisms underlying tolerance to multiple stresses in R. toruloides, underscoring the potential of ALE for enhancing the robustness of industrial yeast strains.

Ibrexafungerp: A narrative overview

Ibrexafungerp (IBX) is a new antifungal drug that recently entered the antifungal landscape. It disrupts fungal cell wall synthesis by non-competitive inhibition of the β-(1,3)-D-glucan (BDG) synthase enzyme. It has demonstrated activity against a range of pathogens including Candida and Aspergillus spp., as well as retaining its activity against azole-resistant and echinocandin-resistant strains. It also exhibits anti-biofilm properties. Pharmacokinetic (PK) studies revealed favorable bioavailability, high protein binding, and extensive tissue distribution with a low potential for CYP-mediated drug interactions. It is characterized by the same mechanism of action of echinocandins with limited cross-resistance with other antifungal agents. Resistance to this drug can arise from mutations in the FKS genes, primarily FKS2 mutations in Nakaseomyces glabrata. In vivo, IBX was found to be effective in murine models of invasive candidiasis (IC) and invasive pulmonary aspergillosis (IPA). It also showed promising results in preventing and treating Pneumocystis jirovecii infections. Clinical trials showed that IBX was effective and non-inferior to fluconazole in treating vulvovaginal candidiasis (VVC), including complicated cases, as well as in preventing its recurrence. These trials positioned it as a Food and Drug Administration (FDA)-approved option for the treatment and prophylaxis of VVC. Trials showed comparable responses to standard-of-care in IC, with favorable preliminary results in C. auris infections in terms of efficacy and tolerability as well as in refractory cases of IC. Mild adverse reactions have been reported including gastrointestinal symptoms. Overall, IBX represents a significant addition to the antifungal armamentarium, with its unique action, spectrum of activity, and encouraging clinical trial results warranting further investigation.

Mitigating candidiasis with acarbose by targeting Candida albicans α-glucosidase: in-silico, in-vitro and transcriptomic approaches

Biofilm-associated candidiasis poses a significant challenge in clinical settings due to the limited effectiveness of existing antifungal treatments. The challenges include increased pathogen virulence, multi-drug resistance, and inadequate penetration of antimicrobials into biofilm structures. One potential solution to this problem involves the development of novel drugs that can modulate fungal virulence and biofilm formation, which is essential for pathogenesis. Resistance in Candida albicans is initiated by morphological changes from yeast to hyphal form. This transition triggers a series of events such as cell wall elongation, increased adhesion, invasion of host tissues, pathogenicity, biofilm formation, and the initiation of an immune response. The cell wall is a critical interface for interactions with host cells, primarily through various cell wall proteins, particularly mannoproteins. Thus, cell wall proteins and enzymes are considered potential antifungal targets. In this regard, we explored α-glucosidase as our potential target which plays a crucial role in processing mannoproteins. Previous studies have shown that inhibition of α-glucosidase leads to defects in cell wall integrity, reduced adhesion, diminished secretion of hydrolytic enzymes, alterations in immune recognition, and reduced pathogenicity. Since α-glucosidase, primarily converts carbohydrates, our study focuses on FDA-approved carbohydrate mimic drugs (Glycomimetics) with well-documented applications in various biological contexts. Through virtual screening of 114 FDA-approved carbohydrate-based drugs, a pseudo-sugar Acarbose, emerged as a top hit. Acarbose is known for its pharmacological potential in managing type 2 diabetes mellitus by targeting α-glucosidase. Our preliminary investigations indicate that Acarbose effectively inhibits C. albicans biofilm formation, reduces virulence, impairs morphological switching, and hinders the adhesion and invasion of host cells, all at very low concentrations in the nanomolar range. Furthermore, transcriptomic analysis reveals the mechanism of action of Acarbose, highlighting its role in targeting α-glucosidase.

A novel functionalized CuTi hybrid nanocomposites: facile one-pot mycosynthesis, characterization, antimicrobial, antibiofilm, antifouling and wastewater disinfection performance

BACKGROUND

The continuous progress in nanotechnology is rapid and extensive with overwhelming futuristic aspects. Through modernizing inventive synthesis protocols, a paradigm leapfrogging in novelties and findings are channeled toward fostering human health and sustaining the surrounding environment. Owing to the overpricing and jeopardy of physicochemical synthesizing approaches, the quest for ecologically adequate schemes is incontestable. By developing environmentally friendly strategies, mycosynthesis of nanocomposites has been alluring.

RESULTS

Herein, a novel architecture of binary CuO and TiO2 in nanocomposites form was fabricated using bionanofactory Candida sp., for the first time. For accentuating the structural properties of CuTi nanocomposites (CuTiNCs), various characterization techniques were employed. UV-Vis spectroscopy detected SPR at 350 nm, and XRD ascertained the crystalline nature of a hybrid system. However, absorption peaks at 8, 4.5, and 0.5 keV confirmed the presence of Cu, Ti and oxygen, respectively, in an undefined assemblage of polygonal-spheres of 15-75 nm aggregated in the fungal matrix of biomolecules as revealed by EDX, SEM and TEM. However, FTIR, ζ-potential and TGA reflected long-term stability (- 27.7 mV) of self-functionalized CuTiNCs. Interestingly, a considerable and significant biocide performance was detected at 50 µg/mL of CuTiNCs against some human and plant pathogens, compared to monometallic counterparts. Further, CuTiNCs (200 µg/mL) ceased significantly the development of Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans biofilms by 80.3 ± 1.4, 68.7 ± 3.0 and 55.7 ± 3.0%, respectively. Whereas, 64.63 ± 3.5 and 89.82 ± 4.3% antimicrofouling potentiality was recorded for 100 and 200 µg/ml of CuTiNCs, respectively; highlighting their destructive effect against marine microfoulers cells and decaying of their extracellular polymeric skeleton as visualized by SEM. Moreover, CuTiNCs (100 and 200 µg/ml) exerted significantly outstanding disinfection potency within 2 h by reducing the microbial load (i.e., total plate count, mold & yeast, total coliforms and faecal Streptococcus) in domestic and agricultural effluents reached >50%.

CONCLUSION

The synergistic efficiency provided by CuNPs and TiNPs in mycofunctionalized CuTiNCs boosted its recruitment as antiphytopathogenic, antibiofilm, antimicrofouling and disinfectant agent in various realms.

Environmental Sustainability and Physicochemical Property Screening of Chitin and Chitin-Glucan from 22 Fungal Species

Thanks to its biobased character with embedded biogenic carbon, chitin can aid in the transition to a sustainable circular economy by replacing fossil carbon from the geosphere. However, meeting current demands for material availability and environmental sustainability requires alternative methods limiting conventional chemical and energy-consuming chitin extraction from crustaceans. To assist future chitinous bioproduct development, this work analyzes the physicochemical properties and potential environmental sustainability of fungal chitin-glucan complexes. A conventional isolation procedure using sodium hydroxide, a weak acid, and short reaction times are applied to the fruiting body of 22 fungal species. Besides, the valorization of underutilized waste streams including Agaricus bisporus and Agaricus brunnescens stipes is investigated. The carbohydrate analysis renders chitin fractions in the range of 9.5-63.5 wt %, while yields vary from 4.2 to 29.9%, and the N-acetylation degree in found in between 53.0 and 98.7%. The sustainability of the process is analyzed using life cycle assessment (LCA), providing impact quantification for global warming potential, terrestrial acidification, freshwater eutrophication, and water use. With 87.5-589.3 kg·CO2-equiv per kilo, potentially lower global warming potential values in comparison to crustacean chitin are achieved. The crystallinity degree ranged from 28 to 78%, while the apparent chitin crystalline size (L020) is between 2.3 and 5.4 nm. Ten of the species yield α-chitin coexisting with semicrystalline glucans. Zwitterionic properties are observed in aqueous solutions, shifting from cationic to anionic at pH 4.5. With its renewable carbon content, fungal chitin is an environmentally sustainable alternative for high-value applications due to its balance of minimal treatment, low carbon footprint, material renewability, ease of isolation, thermal stability, zwitterionic behavior, biodegradability, and noncytotoxicity.

An improved expression and purification protocol enables the structural characterization of Mnt1, an antifungal target from Candida albicans

BACKGROUND

Candida albicans is one of the most prevalent fungi causing infections in the world. Mnt1 is a mannosyltransferase that participates in both the cell wall biogenesis and biofilm growth of C. albicans. While the cell wall performs crucial functions in pathogenesis, biofilm growth is correlated with sequestration of drugs by the extracellular matrix. Therefore, antifungals targeting CaMnt1 can compromise fungal development and potentially also render Candida susceptible to drug therapy. Despite its importance, CaMnt1 has not yet been purified to high standards and its biophysical properties are lacking.

RESULTS

We describe a new protocol to obtain high yield of recombinant CaMnt1 in Komagataella phaffii using methanol induction. The purified protein's identity was confirmed by MALDI-TOF/TOF mass spectroscopy. The Far-UV circular dichroism (CD) spectra demonstrate that the secondary structure of CaMnt1 is compatible with a protein formed by α-helices and β-sheets at pH 7.0. The fluorescence spectroscopy results show that the tertiary structure of CaMnt1 is pH-dependent, with a greater intensity of fluorescence emission at pH 7.0. Using our molecular modeling protocol, we depict for the first time the ternary complex of CaMnt1 bound to its two substrates, which has enabled the identification of residues involved in substrate specificity and catalytic reaction. Our results corroborate the hypothesis that Tyr209 stabilizes the formation of an oxocarbenium ion-like intermediate during nucleophilic attack of the acceptor sugar, opposing the double displacement mechanism proposed by other reports.

CONCLUSIONS

The methodology presented here can substantially improve the yield of recombinant CaMnt1 expressed in flask-grown yeasts. In addition, the structural characterization of the fungal mannosyltransferase presents novelties that can be exploited for new antifungal drug's development.

Natural Substances as Valuable Alternative for Improving Conventional Antifungal Chemotherapy: Lights and Shadows

Fungi are eukaryotic organisms with relatively few pathogenic members dangerous for humans, usually acting as opportunistic infections. In the last decades, several life-threatening fungal infections have risen mostly associated with the worldwide extension of chronic diseases and immunosuppression. The available antifungal therapies cannot combat this challenge because the arsenal of compounds is scarce and displays low selective action, significant adverse effects, and increasing resistance. A growing isolation of outbreaks triggered by fungal species formerly considered innocuous is being recorded. From ancient times, natural substances harvested from plants have been applied to folk medicine and some of them recently emerged as promising antifungals. The most used are briefly revised herein. Combinations of chemotherapeutic drugs with natural products to obtain more efficient and gentle treatments are also revised. Nevertheless, considerable research work is still necessary before their clinical use can be generally accepted. Many natural products have a highly complex chemical composition, with the active principles still partially unknown. Here, we survey the field underlying lights and shadows of both groups. More studies involving clinical strains are necessary, but we illustrate this matter by discussing the potential clinical applications of combined carnosic acid plus propolis formulations.

Chitin-induced disease resistance in plants: A review

Chitin is composed of N-acetylglucosamine units. Chitin a polysaccharide found in the cell walls of fungi and exoskeletons of insects and crustaceans, can elicit a potent defense response in plants. Through the activation of defense genes, stimulation of defensive compound production, and reinforcement of physical barriers, chitin enhances the plant's ability to defend against pathogens. Chitin-based treatments have shown efficacy against various plant diseases caused by fungal, bacterial, viral, and nematode pathogens, and have been integrated into sustainable agricultural practices. Furthermore, chitin treatments have demonstrated additional benefits, such as promoting plant growth and improving tolerance to abiotic stresses. Further research is necessary to optimize treatment parameters, explore chitin derivatives, and conduct long-term field studies. Continued efforts in these areas will contribute to the development of innovative and sustainable strategies for disease management in agriculture, ultimately leading to improved crop productivity and reduced reliance on chemical pesticides.

Nutritive profile, pharmaceutical potentials, and structural analysis of multifunctional bioactive fungal polysaccharides-A review

Asian nations have long used edible fungi as food and medicine. Polysaccharides are among the main building units of the cell walls of fungi. Fungal polysaccharides have been documented in the medicinal and industrial sectors as products with a vast array of various biological activities and applications such as antitumor, antioxidant, anticancer, immunomodulation, and antiviral activities, etc. The goal of this review is to give insights into the various biological activities of mushroom polysaccharides and their potential as a medicine for human health. The extraction, purity, and structural analysis of fungal polysaccharides were also reviewed in this work. Also, future prospective, and challenges for fungal polysaccharides in pharmaceutical applications can be found in this review. Overall, this review serves as a valuable resource in exploring the therapeutic potential and applications of fungal polysaccharides. By building upon the existing knowledge base and addressing critical research gaps, researchers can find new opportunities for utilizing fungal polysaccharides as valuable therapeutic agents and functional ingredients in pharmaceuticals, nutraceuticals, and biotechnology.

Structural and biochemical analysis of family 92 carbohydrate-binding modules uncovers multivalent binding to β-glucans

Carbohydrate-binding modules (CBMs) are non-catalytic proteins found appended to carbohydrate-active enzymes. Soil and marine bacteria secrete such enzymes to scavenge nutrition, and they often use CBMs to improve reaction rates and retention of released sugars. Here we present a structural and functional analysis of the recently established CBM family 92. All proteins analysed bind preferentially to β-1,6-glucans. This contrasts with the diversity of predicted substrates among the enzymes attached to CBM92 domains. We present crystal structures for two proteins, and confirm by mutagenesis that tryptophan residues permit ligand binding at three distinct functional binding sites on each protein. Multivalent CBM families are uncommon, so the establishment and structural characterisation of CBM92 enriches the classification database and will facilitate functional prediction in future projects. We propose that CBM92 proteins may cross-link polysaccharides in nature, and might have use in novel strategies for enzyme immobilisation.

Effect of tryptophan position and lysine/arginine substitution in antimicrobial peptides on antifungal action

Every year, the overprescription, misuse, and improper disposal of antibiotics have led to the rampant development of drug-resistant pathogens and, in turn, a significant increase in the number of patients who die of drug-resistant fungal infections. Recently, researchers have begun investigating the use of antimicrobial peptides (AMPs) as next-generation antifungal agents to inhibit the growth of drug-resistant fungi. The antifungal activity of alpha-helical peptides designed using the cationic amino acids containing lysine and arginine and the hydrophobic amino acids containing isoleucine and tryptophan were evaluated using 10 yeast and mold fungi. Among these peptides, WIK-14, which is composed of a 14-mer with tryptophan sequences at the amino terminus, showed the best antifungal activity via transient pore formation and ROS generation. In addition, the in vivo antifungal effects of WIK-14 were investigated in a mouse model infected with drug-resistant Candida albicans. The results demonstrate the potential of AMPs as antifungal agents.

Unveiling the complexity of early childhood caries: Candida albicans and Streptococcus mutans cooperative strategies in carbohydrate metabolism and virulence

Objective

To explore the mechanisms underlying the virulence changes in early childhood caries (ECC) caused by Candida albicans (C. albicans) and Streptococcus mutans (S. mutans), with a focus on carbohydrate metabolism and environmental acidification.

Methods

A review of literature was conducted to understand the symbiotic relationship between C. albicans and S. mutans, and their role in the pathogenesis of ECC. The review also examined how their interactions influence carbohydrate metabolism and environmental acidification in the oral cavity.

Results

C. albicans and S. mutans play crucial roles in the onset and progression of ECC. C. albicans promotes the adhesion and accumulation of S. mutans, while S. mutans creates an environment favorable for the growth of C. albicans. Their interactions, especially through carbohydrate metabolism, strengthen their pathogenic potential. The review highlights the importance of understanding these mechanisms for the development of effective management and treatment protocols for ECC.

Conclusion

The symbiotic relationship between C. albicans and S. mutans, and their interactions through carbohydrate metabolism and environmental acidification, are key factors in the pathogenesis of ECC. A comprehensive understanding of these mechanisms is crucial for developing effective strategies to manage and treat ECC.

Unravelling the effect of control agents on Gnomoniopsis smithogilvyi on a chestnut-based medium by proteomics

BACKGROUND

Gnomoniopsis smithogilvyi is the major chestnut pathogen, responsible for economic losses and recently described as a 3-nitropropionic acid and diplodiatoxin mycotoxin producer. Bacillus amyloliquefaciens QST 713 (Serenade® ASO), B. amyloliquefaciens CIMO-BCA1, and the fungicide Horizon® (tebuconazole) have been shown to reduce the growth of G. smithogilvyi. However, they enhanced mycotoxin production. Proteomics can clarify the mould's physiology and the impact of antifungal agents on the mould's metabolism. Thus, the aim of this study was to assess the impact of Horizon®, Serenade®, and B. amyloliquefaciens CIMO-BCA1 in the proteome of G. smithogilvyi to unveil their modes of action and decipher why the mould responds by increasing the mycotoxin production. For this, the mycelium close to the inhibition zone provoked by antifungals was macroscopically and microscopically observed. Proteins were extracted and analysed using a Q-Exactive plus Orbitrap.

RESULTS

The results did not elucidate specific proteins involved in the mycotoxin biosynthesis, but these agents provoked different kinds of stress on the mould, mainly affecting the cell wall structures and antioxidant response, which points to the mycotoxins overproduction as a defence mechanism. The biocontrol agent CIMO-BCA1 acts similar to tebuconazole. The results revealed different responses on the mould's metabolism when co-cultured with the two B. amyloliquefaciens, showing different modes of action of each bacterium, which opens the possibility of combining both biocontrol strategies.

CONCLUSION

These results unveil different modes of action of the treatments that could help to reduce the use of toxic chemicals to combat plant pathogens worldwide. © 2023 Society of Chemical Industry.

An update on alternative therapy for Escherichia coli causing urinary tract infections; a narrative review

BACKGROUND

Urinary tract infections (UTIs) are the most common type of nosocomial infection and severe health issues because of the difficulties and frequent recurrence. Today, alternative methods such as sonodynamic therapy (SDT), photodynamic therapy (PDT) and herbal materials use for treating infections like UTI in many countries.

METHOD

We conducted searches of the biomedical databases (Google Scholar, Scopus, PubMed, and Web of sciences) to identify related studies from 2008 to 2023.

RESULT

SDT aims to use ultrasound to activate a sonosensitizer, which causes a biological effect by raising reactive oxygen species (ROS). When bacteria are exposed to ROS, several important effects occur: oxidative damage, DNA damage, protein dysfunction etc. SDT with herbal medicine significantly reduced the number of colony-forming units and bactericidal activity for Klebsiella pneumonia and E. coli. PDT is a promising treatment for cancer and microbial infections, combining a photosensitiser, light and tissue molecular oxygen. It involves a photosensitizer, light source, and oxygen, with variations affecting microbial binding and bactericidal activity. Factors affecting antibacterial properties include plant type, growing conditions, harvesting, and processing. This review highlights the recent advancements in sonodynamic, photodynamic, herbal, and bio-material-based approaches in the treatment of E. coli infections.

CONCLUSIONS

These alternative therapies offer exciting prospects for addressing UTIs, especially in cases where traditional antibiotic treatments may be less effective. Further research and clinical studies are warranted to fully explore the potential of these innovative treatment modalities in combating UTIs and improving patient outcomes.

Targeting Fks1 proteins for novel antifungal drug discovery

Fungal infections are a major threat to human health. The limited availability of antifungal drugs, the emergence of drug resistance, and a growing susceptible population highlight the critical need for novel antifungal agents. The enzymes involved in fungal cell wall synthesis offer potential targets for antifungal drug development. Recent studies have enhanced our focus on the enzyme Fks1, which synthesizes β-1,3-glucan, a critical component of the cell wall. These studies provide a deeper understanding of Fks1's function in cell wall biosynthesis, pathogenicity, structural biology, evolutionary conservation across fungi, and interaction with current antifungal drugs. Here, we discuss the role of Fks1 in the survival and adaptation of fungi, guided by insights from evolutionary and structural analyses. Furthermore, we delve into the dynamics of Fks1 modulation with novel antifungal strategies and assess its potential as an antifungal drug target.

Interplay of Cytokines and Chemokines in Aspergillosis

Aspergillosis is a fungal infection caused by various species of Aspergillus, most notably A. fumigatus. This fungus causes a spectrum of diseases, including allergic bronchopulmonary aspergillosis, aspergilloma, chronic pulmonary aspergillosis, and invasive aspergillosis. The clinical manifestations and severity of aspergillosis can vary depending on individual immune status and the specific species of Aspergillus involved. The recognition of Aspergillus involves pathogen-associated molecular patterns (PAMPs) such as glucan, galactomannan, mannose, and conidial surface proteins. These are recognized by the pathogen recognition receptors present on immune cells such as Toll-like receptors (TLR-1,2,3,4, etc.) and C-type lectins (Dectin-1 and Dectin-2). We discuss the roles of cytokines and pathogen recognition in aspergillosis from both the perspective of human and experimental infection. Several cytokines and chemokines have been implicated in the immune response to Aspergillus infection, including interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), CCR4, CCR17, and other interleukins. For example, allergic bronchopulmonary aspergillosis (ABPA) is characterized by Th2 and Th9 cell-type immunity and involves interleukin (IL)-4, IL-5, IL-13, and IL-10. In contrast, it has been observed that invasive aspergillosis involves Th1 and Th17 cell-type immunity via IFN-γ, IL-1, IL-6, and IL-17. These cytokines activate various immune cells and stimulate the production of other immune molecules, such as antimicrobial peptides and reactive oxygen species, which aid in the clearance of the fungal pathogen. Moreover, they help to initiate and coordinate the immune response, recruit immune cells to the site of infection, and promote clearance of the fungus. Insight into the host response from both human and animal studies may aid in understanding the immune response in aspergillosis, possibly leading to harnessing the power of cytokines or cytokine (receptor) antagonists and transforming them into precise immunotherapeutic strategies. This could advance personalized medicine.

Heavy Metal Remediation by Dry Mycelium Membranes: Approaches to Sustainable Lead Remediation in Water

Lead contamination poses significant and lasting health risks, particularly in children. This study explores the efficacy of dried mycelium membranes, distinct from live fungal biomass, for the remediation of lead (Pb(II)) in water. Dried mycelium offers unique advantages, including environmental resilience, ease of handling, biodegradability, and mechanical reliability. The study explores Pb(II) removal mechanisms through sorption and mineralization by dried mycelium hyphae in aqueous solutions. The sorption isotherm studies reveal a high Pb(II) removal efficiency, exceeding 95% for concentrations below 1000 ppm and ∼63% above 1500 ppm, primarily driven by electrostatic interactions. The measured infrared peak shifts and the pseudo-second-order kinetics for sorption suggests a correlation between sorption capacity and the density of interacting functional groups. The study also explores novel surface functionalization of the mycelium network with phosphate to enhance Pb(II) removal, which enables remediation efficiencies >95% for concentrations above 1500 ppm. Scanning electron microscopy images show a pH-dependent formation of Pb-based crystals uniformly deposited throughout the entire mycelium network. Continuous cross-flow filtration tests employing a dried mycelium membrane demonstrate its efficacy as a microporous membrane for Pb(II) removal, reaching remediation efficiency of 85-90% at the highest Pb(II) concentrations. These findings suggest that dried mycelium membranes can be a viable alternative to synthetic membranes in heavy metal remediation, with potential environmental and water treatment applications.

Proteomic Analysis of Cell Wall Proteins with Various Linkages in Fusarium graminearum

The fungal cell wall, primarily comprising a glucan-chitin matrix and cell wall proteins (CWPs), serves as a key mediator for fungal interactions with the environment and plays a pivotal role in virulence. In this study, we employed a comprehensive proteomics approach to analyze the CWPs in the plant pathogenic fungus Fusarium graminearum. Our methodology successfully extracted and identified 1373 CWPs, highlighting their complex linkages, including noncovalent bonds, disulfide bridges, alkali-sensitive linkages, and glycosylphosphatidylinositol (GPI) anchors. A significant subset of these proteins, enriched in Gene Ontology terms, suggest multifunctional roles of CWPs. Through the integration of transcriptomic and proteomic data, we observed differential expression patterns of CWPs across developmental stages. Specifically, we focused on two genes, Fca7 and Cpd1, which were upregulated in planta, and confirmed their localization predominantly outside the plasma membrane, primarily in the cell wall and periplasmic space. The disruption of FCA7 reduced virulence on wheat, aligning with previous findings and underscoring its significance. Overall, our findings offer a comprehensive proteomic profile of CWPs in F. graminearum, laying the groundwork for a deeper understanding of their roles in the development and interactions with host plants.

Cytotoxic rhamnolipid micelles drive acute virulence in Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic human pathogen that has developed multi- or even pan-drug resistance toward most frontline and last resort antibiotics, leading to increasing frequency of infections and deaths among hospitalized patients, especially those with compromised immune systems. Further complicating treatment, P. aeruginosa produces numerous virulence factors that contribute to host tissue damage and immune evasion, promoting bacterial colonization and pathogenesis. In this study, we demonstrate the importance of rhamnolipid production in host-pathogen interactions. Secreted rhamnolipids form micelles that exhibited highly acute toxicity toward murine macrophages, rupturing the plasma membrane and causing organellar membrane damage within minutes of exposure. While rhamnolipid micelles (RMs) were particularly toxic to macrophages, they also caused membrane damage in human lung epithelial cells, red blood cells, Gram-positive bacteria, and even noncellular models like giant plasma membrane vesicles. Most importantly, rhamnolipid production strongly correlated with P. aeruginosa virulence against murine macrophages in various panels of clinical isolates. Altogether, our findings suggest that rhamnolipid micelles are highly cytotoxic virulence factors that drive acute cellular damage and immune evasion during P. aeruginosa infections.

Antifungal activity of Fe3O4@SiO2/Schiff-base/Cu(II) magnetic nanoparticles against pathogenic Candida species

The antifungal efficacy and cytotoxicity of a novel nano-antifungal agent, the Fe3O4@SiO2/Schiff-base complex of Cu(II) magnetic nanoparticles (MNPs), have been assessed for targeting drug-resistant Candida species. Due to the rising issue of fungal infections, especially candidiasis, and resistance to traditional antifungals, there is an urgent need for new therapeutic strategies. Utilizing Schiff-base ligands known for their broad-spectrum antimicrobial activity, the Fe3O4@SiO2/Schiff-base/Cu(II) MNPs have been synthesized. The Fe3O4@SiO2/Schiff-base/Cu(II) MNPs was characterized by Fourier Transform-Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), Energy-dispersive X-ray (EDX), Vibrating Sample Magnetometer (VSM), and Thermogravimetric analysis (TGA), demonstrating successful synthesis. The antifungal potential was evaluated against six Candida species (C. dubliniensis, C. krusei, C. tropicalis, C. parapsilosis, C. glabrata, and C. albicans) using the broth microdilution method. The results indicated strong antifungal activity in the range of 8-64 μg/mL with the lowest MIC (8 μg/mL) observed against C. parapsilosis. The result showed the MIC of 32 μg/mL against C. albicans as the most common infection source. The antifungal mechanism is likely due to the disruption of the fungal cell wall and membrane, along with increased reactive oxygen species (ROS) generation leading to cell death. The MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay for cytotoxicity on mouse L929 fibroblastic cells suggested low toxicity and even enhanced cell proliferation at certain concentrations. This study demonstrates the promise of Fe3O4@SiO2/Schiff-base/Cu(II) MNPs as a potent antifungal agent with potential applications in the treatment of life-threatening fungal infections, healthcare-associated infections, and beyond.

Preliminary characterization of gut mycobiome enterotypes reveals the correlation trends between host metabolic parameter and diet: a case study in the Thai Cohort

The association between the gut mycobiome and its potential influence on host metabolism in the Thai Cohort was assessed. Two distinct predominant enterotypes, Saccharomyces (Sa) and Aspergillus/Penicillium (Ap/Pe) showed differences in gut mycobiota diversity and composition. Notably, the Sa enterotype exhibited lower evenness and richness, likely due to the prevalence of Saccharomyces, while both enterotypes displayed unique metabolic behaviors related to nutrient metabolism and body composition. Fiber consumption was positively correlated with adverse body composition and fasting glucose levels in individuals with the Sa enterotype, whereas in the Ap/Pe enterotype it was positively correlated with fat and protein intake. The metabolic functional analysis revealed the Sa enterotype associated with carbohydrate metabolism, while the Ap/Pe enterotype involved in lipid metabolism. Very interestingly, the genes involved in the pentose and glucuronate interconversion pathway, such as polygalacturonase and L-arabinose-isomerase, were enriched in the Sa enterotype signifying a metabolic capacity for complex carbohydrate degradation and utilization of less common sugars as energy sources. These findings highlight the interplay between gut mycobiome composition, dietary habits, and metabolic outcomes within the Thai cohort studies.

Exploring fungal bioemulsifiers: insights into chemical composition, microbial sources, and cross-field applications

The demand for emulsion-based products is crucial for economic development and societal well-being, spanning diverse industries such as food, cosmetics, pharmaceuticals, and oil extraction. Formulating these products relies on emulsifiers, a distinct class of surfactants. However, many conventional emulsifiers are derived from petrochemicals or synthetic sources, posing potential environmental and human health risks. In this context, fungal bioemulsifiers emerge as a compelling and sustainable alternative, demonstrating superior performance, enhanced biodegradability, and safety for human consumption. From this perspective, the present work provides the first comprehensive review of fungal bioemulsifiers, categorizing them based on their chemical nature and microbial origin. This includes polysaccharides, proteins, glycoproteins, polymeric glycolipids, and carbohydrate-lipid-protein complexes. Examples of particular interest are scleroglucan, a polysaccharide produced by Sclerotium rolfsii, and mannoproteins present in the cell walls of various yeasts, including Saccharomyces cerevisiae. Furthermore, this study examines the feasibility of incorporating fungal bioemulsifiers in the food and oil industries and their potential role in bioremediation events for oil-polluted marine environments. Finally, this exploration encourages further research on fungal bioemulsifier bioprospecting, with far-reaching implications for advancing sustainable and eco-friendly practices across various industrial sectors.

Effect of meso-substituents and medium properties on the photo- and pH-stability, penetration efficiency into bacterial and microscopic fungi cells of terpene-BODIPY conjugates

In order to expand the arsenal of tools and areas for practical use of BODIPY dyes as bifunctional fluorescent theranostics, we studied the effect of the meso-substituents nature and medium properties on photo- and pH-stability, efficiency of singlet oxygen generation, and affinity to biostructures of terpene-BODIPY conjugates. The BODIPYs fused with myrtenol or thiotherpenoid via carboxylic acid residues exhibit high stability over a wide pH range and the presence of a bulky substituent at the meso-position of BODIPY conjugates increases their photostability two-fold compared to structurally related meso-unsubstituted analogues. Furthermore, the photodegradation rate of the conjugates directly depends on their ability to generate singlet oxygen and the course probability of the corresponding red-ox reactions involving reactive oxygen species. The conjugate of BODIPY with a thiotherpenoid demonstrated high ability to penetrate the membranes of filamentous and yeast-like fungi and bind to membrane of organelles in the fungal cell. At the same time, this compound also had a high ability to penetrate into biofilms of Staphylococcus aureus and Klebsiella pneumoniae and into bacterial cells within the matrix, which makes this compound promising for staining intracellular structures of eukaryotic cells and bacteria embedded into biofilms.

Expression of BSN314 lysozyme genes in Escherichia coli BL21: a study to demonstrate microbicidal and disintegarting potential of the cloned lysozyme

This study is an extension of our previous studies in which the lysozyme was isolated and purified from Bacillus subtilis BSN314 (Naveed et al., 2022; Naveed et al., 2023). In this study, the lysozyme genes were cloned into the E. coli BL21. For the expression of lysozyme in E. coli BL21, two target genes, Lyz-1 and Lyz-2, were ligated into the modified vector pET28a to generate pET28a-Lyz1 and pET28a-Lyz2, respectively. To increase the production rate of the enzyme, 0.5-mM concentration of IPTG was added to the culture media and incubated at 37 °C and 220 rpm for 24 h. Lyz1 was identified as N-acetylmuramoyl-L-alanine amidase and Lyz2 as D-alanyl-D-alanine carboxypeptidase. They were purified by multi-step methodology (ammonium sulfate, precipitation, dialysis, and ultrafiltration), and antimicrobial activity was determined. For Lyz1, the lowest MIC/MBC (0.25 μg/mL; with highest ZOI = 22 mm) were recorded against Micrococcus luteus, whereas the highest MIC/MBC with lowest ZOI were measured against Salmonella typhimurium (2.50 μg /mL; with ZOI = 10 mm). As compared with Aspergillus oryzae (MIC/MFC; 3.00 μg/mL), a higher concentration of lysozyme was required to control the growth of Saccharomyces cerevisiae (MIC/MFC; 50 μg/mL). Atomic force microscopy (AFM) was used to analyze the disintegrating effect of Lyz1 on the cells of selected Gram-positive bacteria, Gram-negative bacteria, and yeast. The AFM results showed that, as compared to Gram-negative bacteria, a lower concentration of lysozyme (Lyz1) was required to disintegrate the cell of Gram-positive bacteria.

Fungal Cell Wall-Associated Effectors: Sensing, Integration, Suppression, and Protection

The cell wall (CW) of plant-interacting fungi, as the direct interface with host plants, plays a crucial role in fungal development. A number of secreted proteins are directly associated with the fungal CW, either through covalent or non-covalent interactions, and serve a range of important functions. In the context of plant-fungal interactions many are important for fungal development in the host environment and may therefore be considered fungal CW-associated effectors (CWAEs). Key CWAE functions include integrating chemical/physical signals to direct hyphal growth, interfering with plant immunity, and providing protection against plant defenses. In recent years, a diverse range of mechanisms have been reported that underpin their roles, with some CWAEs harboring conserved motifs or functional domains, while others are reported to have novel features. As such, the current understanding regarding fungal CWAEs is systematically presented here from the perspective of their biological functions in plant-fungal interactions. An overview of the fungal CW architecture and the mechanisms by which proteins are secreted, modified, and incorporated into the CW is first presented to provide context for their biological roles. Some CWAE functions are reported across a broad range of pathosystems or symbiotic/mutualistic associations. Prominent are the chitin interacting-effectors that facilitate fungal CW modification, protection, or suppression of host immune responses. However, several alternative functions are now reported and are presented and discussed. CWAEs can play diverse roles, some possibly unique to fungal lineages and others conserved across a broad range of plant-interacting fungi. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Reshaping Echinocandin Antifungal Drugs To Circumvent Glucan Synthase Point-Mutation-Mediated Resistance

Echinocandins are a class of antifungal drugs that inhibit the activity of the β-(1,3)-glucan synthase complex, which synthesizes fungal cell wall β-(1,3)-glucan. Echinocandin resistance is linked to mutations in the FKS gene, which encodes the catalytic subunit of the glucan synthase complex. We present a molecular-docking-based model that provides insight into how echinocandins interact with the target Fks protein: echinocandins form a ternary complex with both Fks and membrane lipids. We used reductive dehydration of alcohols to generate dehydroxylated echinocandin derivatives and evaluated their potency against a panel of Candida pathogens constructed by introducing resistance-conferring mutations in the FKS gene. We found that removing the hemiaminal alcohol, which drives significant conformational alterations in the modified echinocandins, reduced their efficacy. Conversely, eliminating the benzylic alcohol of echinocandins enhanced potency by up to two orders of magnitude, in a manner dependent upon the resistance-conferring mutation. Strains that have developed resistance to either rezafungin, the most recently clinically approved echinocandin, or its dehydroxylated derivative RZF-1, exhibit high resistance to rezafungin while demonstrating moderate resistance to RZF-1. These findings provide valuable insight for combating echinocandin resistance through chemical modifications.

Innovations in Antifungal Drug Discovery among Cell Envelope Synthesis Enzymes through Structural Insights

Life-threatening systemic fungal infections occur in immunocompromised patients at an alarming rate. Current antifungal therapies face challenges like drug resistance and patient toxicity, emphasizing the need for new treatments. Membrane-bound enzymes account for a large proportion of current and potential antifungal targets, especially ones that contribute to cell wall and cell membrane biosynthesis. Moreover, structural biology has led to a better understanding of the mechanisms by which these enzymes synthesize their products, as well as the mechanism of action for some antifungals. This review summarizes the structures of several current and potential membrane-bound antifungal targets involved in cell wall and cell membrane biosynthesis and their interactions with known inhibitors or drugs. The proposed mechanisms of action for some molecules, gleaned from detailed inhibitor-protein studeis, are also described, which aids in further rational drug design. Furthermore, some potential membrane-bound antifungal targets with known inhibitors that lack solved structures are discussed, as these might be good enzymes for future structure interrogation.

Influence of Salinity on the Extracellular Enzymatic Activities of Marine Pelagic Fungi

Even though fungi are ubiquitous in the biosphere, the ecological knowledge of marine fungi remains rather rudimentary. Also, little is known about their tolerance to salinity and how it influences their activities. Extracellular enzymatic activities (EEAs) are widely used to determine heterotrophic microbes' enzymatic capabilities and substrate preferences. Five marine fungal species belonging to the most abundant pelagic phyla (Ascomycota and Basidiomycota) were grown under non-saline and saline conditions (0 g/L and 35 g/L, respectively). Due to their sensitivity and specificity, fluorogenic substrate analogues were used to determine hydrolytic activity on carbohydrates (β-glucosidase, β-xylosidase, and N-acetyl-β-D-glucosaminidase); peptides (leucine aminopeptidase and trypsin); lipids (lipase); organic phosphorus (alkaline phosphatase), and sulfur compounds (sulfatase). Afterwards, kinetic parameters such as maximum velocity (Vmax) and half-saturation constant (Km) were calculated. All fungal species investigated cleaved these substrates, but some species were more efficient than others. Moreover, most enzymatic activities were reduced in the saline medium, with some exceptions like sulfatase. In non-saline conditions, the average Vmax ranged between 208.5 to 0.02 μmol/g biomass/h, and in saline conditions, 88.4 to 0.02 μmol/g biomass/h. The average Km ranged between 1553.2 and 0.02 μM with no clear influence of salinity. Taken together, our results highlight a potential tolerance of marine fungi to freshwater conditions and indicate that changes in salinity (due to freshwater input or evaporation) might impact their enzymatic activities spectrum and, therefore, their contribution to the oceanic elemental cycles.

Chelation of Mitochondrial Iron as an Antiparasitic Strategy

Iron, as an essential micronutrient, plays a crucial role in host-pathogen interactions. In order to limit the growth of the pathogen, a common strategy of innate immunity includes withdrawing available iron to interfere with the cellular processes of the microorganism. Against that, unicellular parasites have developed powerful strategies to scavenge iron, despite the effort of the host. Iron-sequestering compounds, such as the approved and potent chelator deferoxamine (DFO), are considered a viable option for therapeutic intervention. Since iron is heavily utilized in the mitochondrion, targeting iron chelators in this organelle could constitute an effective therapeutic strategy. This work presents mitochondrially targeted DFO, mitoDFO, as a candidate against a range of unicellular parasites with promising in vitro efficiency. Intracellular Leishmania infection can be cleared by this compound, and experimentation with Trypanosoma brucei 427 elucidates its possible mode of action. The compound not only affects iron homeostasis but also alters the physiochemical properties of the inner mitochondrial membrane, resulting in a loss of function. Furthermore, investigating the virulence factors of pathogenic yeasts confirms that mitoDFO is a viable candidate for therapeutic intervention against a wide spectrum of microbe-associated diseases.

Efficacy of rhizobacteria Paenibacillus polymyxa SY42 for the biological control of Atractylodes chinensis root rot

Atractylodes chinensis is one of the most commonly used bulk herbs in East Asia; however, root rot can seriously affect its quality and yields. In contrast to chemical pesticides, biological control strategies are environmentally compatible and safe. For this study, 68 antagonistic bacterial strains were isolated from the rhizospheres of healthy Atractylodes chinensis. Strain SY42 exhibited the most potent fungicidal activities, with inhibition rates against F. oxysporum, F. solani, and F. redolens of 67.07 %, 63.40 % and 68.45 %, respectively. Through morphological observation and molecular characterization, strain SY42 was identified as Paenibacillus polymyxa. The volatile organic components (VOCs) produced by SY42 effectively inhibited the mycelial growth of pathogenic fungi through diffusion. SY42 significantly inhibited the germination of pathogenic fungal spores. Following co-culturing with SY42, the mycelium of the pathogenic fungus was deformed, folded, and even ruptured. SY42 could produce cellulases and proteases to degrade fungal cell walls. Pot experiments demonstrated the excellent biocontrol efficacy of SY42. This study revealed that P. polymyxa SY42 inhibited pathogenic fungi through multiple mechanisms, which verified its utility as a biocontrol agent for the control of A. chinensis root rot.