Mildew Resistance Research Articles

Microstructural and physicochemical quality maintenance in green bell pepper infected with Botrytis cinerea and treated with thyme essential oil combined with carnauba wax.

Bell pepper presents rapid weight loss and is highly susceptible to gray mold caused by the fungus Botrytis cinerea. The most employed method to control this disease is the application of synthetic fungicides such as thiabendazole (TBZ); however, its continued use causes resistance in fungi as well as environmental problems. For these reasons, natural alternatives arise as a more striking option. Currently, bell pepper fruits are coated with carnauba wax (CW) to prevent weight loss and improve appearance. Moreover, CW can be used as a carrier to incorporate essential oils, and previous studies have shown that thyme essential oil (TEO) is highly effective against B. cinerea. Therefore, this study aimed to evaluate the effect of CW combined with TEO on the development of gray mold and maintenance of microestructural and postharvest quality in bell pepper stored at 13°C. The minimal inhibitory concentration of TEO was 0.5%. TEO and TBZ provoked the leakage of intracellular components. TEO and CW+TEO treatments were equally effective to inhibit the development of gray mold. On the quality parameters, firmness and weight loss were ameliorated with CW and CW+TEO treatments; whereas lightness increased in these treatments. The structural analysis showed that CW+TEO treatment maintained the cell structure reducing the apparition of deformities. The results suggest that CW+TEO treatment could be used as a natural and effective antifungal retarding the appearance of gray mold and maintaining the postharvest quality of bell pepper. PRACTICAL APPLICATION: CW and TEO are classified as generally recognized as safe (GRAS) by the US Food and Drug Administration (FDA). This combination can be employed on the bell pepper packaging system to extend shelf life and oppose gray mold developments. Bell pepper fruits are normally coated with lipid-base coatings such as CW before commercialization; therefore, TEO addition would represent a small investment without any changes on the packaging system infrastructure.

Camellia meal-based adhesive with synergistic crosslinking of physical and chemical interaction for preparing aldehyde-free, anti-mildew, water-resistant wood-based composites

Wood adhesives containing toxic aldehyde-based adhesives play a vital role in the performance of wood-based panels, while the mechanical properties and water and mildew resistance of aldehyde-free adhesives are lacking. In this study, a high-strength aldehyde-free adhesive was constructed via a combination of physical and chemical crosslinks. Inexpensive alum was used to ensure a high degree of crosslinking and to increase the crystallinity. Metal ions in alum opened the protein helix, exposed the active groups, increased the number of hydrogen bonds, and ultimately improved the internal physical crosslinking ability of the adhesive. The compound formed by the Schiff base reaction formed coordination bonds with metal ions, thus forming a covalently-crosslinked network. The high-strength polymer produced in this study contained multiple physical and covalent crosslinks, resulting in significantly improved mechanical properties of the adhesive. Its water-resistant adhesive strength reached 1.96 MPa, which was 180.2% higher than that of ordinary phytogenic protein adhesive (0.69 MPa), and it can still reach 1.28 MPa after hot water circulation soaking experiment. The adhesive also possessed antifungal properties and flame-retardant capabilities, achieving a V-1 rating in the UL-94 test. This strategy expanded the application of phytogenic protein adhesives in environmentally friendly wood composite materials by replacing synthetic resins that released formaldehyde and provided an economical and feasible industrial scale production method for the preparation of high strength, water, and mildew resistant, flame retardant indoor and outdoor wood-based panels.

Phaseolus vulgaris STP13.1 is an H+-coupled monosaccharide transporter, present in source leaves and seed coats, with higher substrate affinity at depolarized potentials.

Sugar transport proteins (STPs) are high-affinity H+-coupled hexose symporters. Recently, the contribution of STP13 to bacterial and fungal pathogen resistance across multiple plant species has garnered significant interest. Quantitative PCR analysis of source leaves, developing embryos, and seed coats of Phaseolus vulgaris L. (common bean) revealed that PvSTP13.1 was expressed in source leaves and seed coats throughout seed development. In contrast, PvSTP13.1 transcripts were detected at exceedingly low levels in developing embryos. To characterize the transport mechanism, PvSTP13.1 was expressed in Xenopus laevis oocytes, and inward-directed currents were analyzed using two-electrode voltage clamping. PvSTP13.1 was shown to function as an H+-coupled monosaccharide symporter exhibiting a unique high affinity for hexoses and aldopentoses at depolarized membrane potentials. Specifically, of the 31 assessed substrates, which included aldohexoses, deoxyhexoses, fructose, 3-O-methyl-D-glucose, aldopentoses, polyols, glycosides, disaccharides, trisaccharides, and glucuronic acid, PvSTP13.1 displayed the highest affinity (K 0.5) for glucose (43 μM), mannose (92 μM), galactose (145 μM), fructose (224 μM), xylose (1.0mM), and fucose (3.7mM) at pH5.6 at a depolarized membrane potential of -40 mV. The results presented here suggest PvSTP13.1 contributes to retrieval of hexoses from the apoplasmic space in source leaves and coats of developing seeds.

QTL Mapping of Adult Plant Resistance to Powdery Mildew in Chinese Wheat Landrace Baidatou.

Wheat powdery mildew, caused by the biotrophic fungus Blumeria graminis f. sp. tritici (Bgt), is one of the most devastating diseases affecting wheat throughout the world. Breeding and growing resistant wheat cultivars is one of the most economic and effective methods to control the disease, and as such, identifying and mapping the new and effective resistance genes is critical. Baidatou, a Chinese wheat landrace, shows excellent field resistance to powdery mildew. To identify the resistance gene(s) in Baidatou, 170 F7:8 recombinant inbred lines (RILs) derived from the cross Mingxian 169/Baidatou were evaluated for powdery mildew response at the adult-plant stage in the experimental fields in Yangling (YL) of Shaanxi Province and Tianshui (TS) in Gansu Province in 2019, 2020, and 2021. The relative area under disease progress curve (rAUDPC) of Mingxian 169/Baidatou F7:8 RILs indicated that the resistance of Baidatou to powdery mildew was controlled by quantitative trait loci (QTLs). Based on bulk segregation analysis combined with the 660K single nucleotide polymorphism (SNP) array and genotyping by target sequencing (16K SNP) of the entire RIL population, two QTLs, QPmbdt.nwafu-2AS and QPmbdt.nwafu-3AS, were identified, and these accounted for up to 44.5% of the phenotypic variation. One of the QTLs was located on the 3.32 cM genetic interval on wheat chromosome 2AS between the kompetitive allele-specific PCR markers AX-111012288 and AX_174233809, and another was located on the 9.6 cM genetic interval on chromosome 3AS between the SNP markers 3A_684044820 and 3A_686681822. These markers could be useful for successful breeding of powdery mildew resistance in wheat.

Phytolacca tetramera berries extracts and its main constituents as potentiators of antifungal drugs against Candida spp.

BackgroundExtensive antifungal drug use has enhanced fungal resistance, resulting in persistent mycoses. Combining antifungal plant extracts/compounds with these drugs offers good alternatives to increase the activity of both partners, minimize side effects, and overcome drug resistance. In our previous study, Phytolacca tetramera berries extracts demonstrated activity against Candida spp., correlating with the amount of the main constituent phytolaccoside B and its genin, phytolaccagenin. The extracts and phytolaccagenin altered the fungal plasma membrane by binding to ergosterol, whereas phytolaccoside B increased chitin synthase activity. However, the presence of triterpenoid saponins in Phytolacca spp. has been linked to acute toxicity in humans. PurposeThis study aimed to evaluate combinations of P. tetramera berries extracts, phytolaccoside B and phytolaccagenin, together with commercial antifungals [amphotericin B, fluconazole, itraconazole, posaconazole, and caspofungin] against Candida albicans and Candida glabrata, to find synergistic effects with multi-target actions, in which the doses of both partners are reduced, and therefore their toxicity. Additionally, we intended to explore their anti-virulence capacity, thereby hindering the development of drug-resistant strains. MethodsThe effects of these combinations were evaluated using both the checkerboard and isobologram methods. Fractional Inhibitory Concentration Index and Dose Reduction Index were calculated to interpret the combination results. To confirm the multi-target effect, studies on mechanisms of action of synergistic mixtures were performed using ergosterol-binding and quantification assays. The ability to inhibit Candida virulence factors, including biofilm formation and eradication from inert surfaces, was also evaluated. Quantification of active markers was performed using a validated UHPLC-ESI-MS method. ResultsEight synergistic combinations of P. tetramera extracts or phytolaccagenin (but not phytolaccoside B) with itraconazole or posaconazole were obtained against C. albicans, including a resistant strain. These mixtures acted by binding to ergosterol, decreasing its whole content, and inhibiting Candida biofilm formation in 96-well microplates and feeding tubes in vitro, but were unable to eradicate preformed biofilms. ConclusionsThis study demonstrated the synergistic and anti-virulence effects of P. tetramera berries extracts and phytolaccagenin with antifungal drugs against Candida spp., providing novel treatment avenues for fungal infections with reduced doses of both natural products and commercial antifungals, thereby mitigating potential human toxicity concerns.

Antimicrobial resistance as a global public health threat: the way forward

Increased antimicrobial resistance (AMR) of bacterial and fungal pathogens pose a significant threat to public health, as it reduces the effectiveness of antibiotic and other antimicrobial drugs, making the control of infections difficult or almost impossible. This condition arises when microorganisms evolve and develop adaptive mechanisms to withstand the effects of the drugs which are designed to kill them. The emergence and spread of these antimicrobial pathogens that have acquired new resistance mechanisms continue to endanger and undermine efforts to treat common infections. As a result, an increase in morbidity and mortality due to bacterial and fungal infections has been observed with a ripple effect of economic hardship. The primary drivers of AMR include misuse and abuse in human, animal and the environment. To address this threat, it is important to have a good understanding of the cause, consequences, as well as the potential control strategies. Due to the cause and nature of AMR, a multidisciplinary approach is necessary in combating the threat posed by this condition. Some of the strategies through which AMR can be combatted include public health awareness, proper antibiotic use, accurate diagnosis, and research into the development of newer antimicrobial agents and alternative treatments. Additionally, the use of improved surveillance and monitoring systems are important in tracking patterns of resistance and provide guide towards the development of effective intervention strategies. Hence, this review focused on bacterial and fungal resistance to increase awareness and the way forward on this growing threat to human existence

Drug Design: Do Not Forget the Supramolecular Factor.

A major challenge currently facing medicinal chemists is designing agents that can selectively destroy drug resistant fungi and bacteria that have begun to emerge. One factor that has been overlooked by virtually all drug discovery/development approaches is the supramolecular factor, in which aggregated forms of a drug candidate exhibit low selectivity in destroying targeted cells while the corresponding monomers exhibit high selectivity. This Perspective discusses how we were led to the supramolecular factor through fundamental studies with simple model systems, how we reasoned that the selectivity of monomers of the antifungal agent amphotericin B should be much greater than the selectivity of the corresponding aggregates, and how we confirmed this hypothesis using derivatives of amphotericin B. In a broader context, these findings provide a strong rationale for considering the supramolecular factor in the design of new drug candidates and the testing of virtually all of them.

A diverse panel of 755 bread wheat accessions harbors untapped genetic diversity in landraces and reveals novel genetic regions conferring powdery mildew resistance

Key message A bread wheat panel reveals rich genetic diversity in Turkish, Pakistani and Iranian landraces and novel resistance loci to diverse powdery mildew isolates via subsetting approaches in association studies.Wheat breeding for disease resistance relies on the availability and use of diverse genetic resources. More than 800,000 wheat accessions are globally conserved in gene banks, but they are mostly uncharacterized for the presence of resistance genes and their potential for agriculture. Based on the selective reduction of previously assembled collections for allele mining for disease resistance, we assembled a trait-customized panel of 755 geographically diverse bread wheat accessions with a focus on landraces, called the LandracePLUS panel. Population structure analysis of this panel based on the TaBW35K SNP array revealed an increased genetic diversity compared to 632 landraces genotyped in an earlier study and 17 high-quality sequenced wheat accessions. The additional genetic diversity found here mostly originated from Turkish, Iranian and Pakistani landraces. We characterized the LandracePLUS panel for resistance to ten diverse isolates of the fungal pathogen powdery mildew. Performing genome-wide association studies and dividing the panel further by a targeted subsetting approach for accessions of distinct geographical origin, we detected several known and already cloned genes, including the Pm2a gene. In addition, we identified 22 putatively novel powdery mildew resistance loci that represent useful sources for resistance breeding and for research on the mildew-wheat pathosystem. Our study shows the value of assembling trait-customized collections and utilizing a diverse range of pathogen races to detect novel loci. It further highlights the importance of integrating landraces of different geographical origins into future diversity studies.

Biochemical Changes: Their Potential Role against Fungal Disease Resistance Development in Mustard

Rape-seed mustard is an imperative edible oilseed crop which is adversely affected by different biotic stresses causing import of edible oils from abroad. The experiment was carried out for screening mustard genotypes based on disease indexing and putative role of diverse biochemical parameters in development of resistant against three major fungal diseases. A modified 0-9 scale was used for rating of disease indicators to calculate disease incident (DI). In disease indexing, mustard genotypes L-4, GSC-7 and PC-6 were considered as immune against Alternaria brassicae, Maya, L-4, China, GSL-1, GSC-7, PC-5, PC-6 and RP-9 were classified as immune against Albugo candida while L-4 and PC-5 were found immune against Erysiphe cruciferarum. The study of biochemical constituents demonstrated that these immune genotypes accumulated higher osmolytes content including free proline content and total phenol under diseased condition showing their tolerance ability against these pathogens. The tolerant genotypes also had lesser lipid peroxidation rate as indicated by malondialdehyde content analysis to induce lesser effect on total chlorophyll, amino acids, proteins and soluble sugars including reducing and non-reducing sugars. These identified genotypes have wider scope for further phyto-pathological studies and utilization in development of fungal resistance breeding.

Characterization of the powdery mildew resistance locus in wheat breeding line Jimai 809 and its breeding application.

The online version contains supplementary material available at 10.1007/s11032-024-01467-8.

Identification and Transfer of a New Powdery Mildew Resistance Gene PmCAHM from Landrace Changanhongmai into Common Wheat

Powdery mildew is a severe wheat disease that causes substantial yield losses in wheat production worldwide. The Chinese wheat landrace Changanhongmai (CAHM) exhibits high resistance to the physiological race E09 of powdery mildew. In this study, we characterized the powdery mildew resistance gene in CAHM, and developed molecular markers for wheat marker-assisted selection. To investigate the genetic characteristics of this resistant gene, we developed F1 plants, F2 generation population, and F2:3 families by crossing CAHM with SY225 (Shaanyou ‘225’ as susceptible male parent). Genetic analysis demonstrated that all F1 plants were resistant to the disease, while the ratio of resistant to susceptible plants was 3: 1 in both the F2 population and F2:3 families, indicating that CAHM is inherited in a manner of a single dominant powdery mildew resistance gene, which was tentatively designated as PmCAHM. By using bulk segregation analysis, we constructed a genetic map encompassing Xgwm273, Xwmc626, Xgwm11, Xgwm18, Xgdm28, Xgpw7812, Xgpw5195, Xwmc694, and PmCAHM. Among these markers, Xgpw7812 and Xgpw5195 are flanking markers that are tightly linked to PmCAHM at a genetic distance of 2.5 cM and 8.4 cM, respectively. Furthermore, nullisomic-tetrasomic analysis revealed that PmCAHM is located on chromosome 1B. These results indicate that PmCAHM differs from the internationally recognized powdery mildew resistance genes in both location and source. In addition, a new germplasm/line NW1748 with stronger powdery mildew resistance and large grains was developed from the cross and backcross populations of Fengyou1718 (FY1718)/CAHM/5/FY 1718. Therefore, PmCAHM can serve as a novel powdery mildew resistance source for breeding of wheat by using NW1748 as the donor in the future.

Enzymes with Lactonase Activity against Fungal Quorum Molecules as Effective Antifungals.

Since the growing number of fungi resistant to the fungicides used is becoming a serious threat to human health, animals, and crops, there is a need to find other effective approaches in the eco-friendly suppression of fungal growth. One of the main mechanisms of the development of resistance in fungi, as well as in bacteria, to antimicrobial agents is quorum sensing (QS), in which various lactone-containing compounds participate as signaling molecules. This work aimed to study the effectiveness of action of enzymes exhibiting lactonase activity against fungal signaling molecules. For this, the molecular docking method was used to estimate the interactions between these enzymes and different lactone-containing QS molecules of fungi. The catalytic characteristics of enzymes such as lactonase AiiA, metallo-β-lactamase NDM-1, and organophosphate hydrolase His6-OPH, selected for wet experiments based on the results of computational modeling, were investigated. QS lactone-containing molecules (butyrolactone I and γ-heptalactone) were involved in the experiments as substrates. Further, the antifungal activity of the enzymes was evaluated against various fungal and yeast cells using bioluminescent ATP-metry. The efficient hydrolysis of γ-heptalactone by all three enzymes and butyrolactone I by His6-OPH was demonstrated for the first time. The high antifungal efficacy of action of AiiA and NDM-1 against most of the tested fungal cells was revealed.

Chimeric mutations in grapevine ENHANCED DISEASE RESISTANCE1 improve resistance to powdery mildew without growth penalty.

Grapevine (Vitis vinifera L.) incurs severe quality degradation and yield loss from powdery mildew, a major fungal disease caused by Erysiphe necator. ENHANCED DISEASE RESISTANCE1 (EDR1), a Raf-like mitogen-activated protein kinase kinase kinase, negatively regulates defense responses against powdery mildew in Arabidopsis (Arabidopsis thaliana). However, little is known about the role of the putatively orthologous EDR1 gene in grapevine. In this study, we obtained grapevine VviEDR1-edited lines using CRISPR/Cas9. Plantlets containing homozygous and bi-allelic indels in VviEDR1 developed leaf lesions shortly after transplanting into the soil and died at the seedling stage. Transgenic plants expressing wild-type VviEDR1 and mutant Vviedr1 alleles as chimera (designated as VviEDR1-chi) developed normally and displayed enhanced resistance to powdery mildew. Interestingly, VviEDR1-chi plants maintained a spatiotemporally distinctive pattern of VviEDR1 mutagenesis: while almost no mutations were detected from terminal buds, ensuring normal function of the apical meristem, mutations occurred in young leaves and increased as leaves matured, resulting in resistance to powdery mildew. Further analysis showed that the resistance observed in VviEDR1-chi plants was associated with callose deposition, increased production of salicylic acid and ethylene, H2O2 production and accumulation, and host cell death. Surprisingly, no growth penalty was observed with VviEDR1-chi plants. Hence, this study demonstrated a role of VviEDR1 in the negative regulation of resistance to powdery mildew in grapevine and provided an avenue for engineering powdery mildew resistance in grapevine.

Hsp90-Mediated Multi-Drug Resistance in DNA Polymerase-Defective Strains of Candida albicans.

The incidence of infections caused by Candida species, specifically by drug-resistant isolates, is a major health concern as they can disseminate to and colonize most vital organs, enhancing morbidity and mortality. Several molecular mechanisms have been reported to be involved in drug resistance. These are mostly drug- and isolate-specific. Here, we characterized three different genetically modified strains of C. albicans that were multi-drug-resistant (MDR) and deciphered a uniform mechanism responsible for resistance. DNA polymerase epsilon (Polε) is a leading strand-specific polymerase consisting of four subunits, namely, Pol2, Dpb2, Dpb3, and Dpb4. The deletion of one or both of the Dpb3 and Dpb4 subunits in C. albicans rendered multi-drug resistance. A detailed characterization of these strains revealed that acquired mutagenesis, drug efflux pumps, and other known mechanisms did not play a significant role because the complemented strain showed drug sensitivity. More importantly, the function of heat shock protein 90 (Hsp90) in these knockout strains is critical for reducing susceptibility to several antifungal drugs. Cell wall deformity and composition in these strains can add to such a phenotype. The inhibition of Hsp90 function by geldanamycin and tricostatin A sensitized the MDR strains to antifungals. Considering our earlier research and this report, we suggest that replication stress induces Hsp90 expression and activity in order to orchestrate a cellular stress response circuit and thus develop fungal drug resistance. Thus, Hsp90 is an important drug target for use in combinatorial therapy.

Wheat powdery mildew resistance gene Pm13 encodes a mixed lineage kinase domain-like protein

Wheat powdery mildew is one of the most destructive diseases threatening global wheat production. The wild relatives of wheat constitute rich sources of diversity for powdery mildew resistance. Here, we report the map-based cloning of the powdery mildew resistance gene Pm13 from the wild wheat species Aegilops longissima. Pm13 encodes a mixed lineage kinase domain-like (MLKL) protein that contains an N-terminal-domain of MLKL (MLKL_NTD) domain in its N-terminus and a C-terminal serine/threonine kinase (STK) domain. The resistance function of Pm13 is validated by mutagenesis, gene silencing, transgenic assay, and allelic association analyses. The development of introgression lines with significantly reduced chromosome segments of Ae. longissima encompassing Pm13 enables widespread deployment of this gene into wheat cultivars. The cloning of Pm13 may provide valuable insights into the molecular mechanisms underlying Pm13-mediated powdery mildew resistance and highlight the important roles of kinase fusion proteins (KFPs) in wheat immunity.

You don't win friends with bad salad! A gene editing approach to enhance the powdery mildew resistance in cucumber.

You don't win friends with bad salad! A gene editing approach to enhance the powdery mildew resistance in cucumber.

The efficacy of non-equilibrium dielectric barrier discharge in air on the elimination of phytopathogenic fungi from wooden surface

Despite the use of modern transport and storage techniques, post-harvest losses of fruit and vegetables due to diseases are a major global problem. Therefore, it is necessary to stop or prevent the development of infectious diseases at all stages of plant production. In response to this problem, we proposed an atmospheric plasma with a dielectric barrier discharge (DBD) in air as a biocidal technique for the eradication of phytopathogens: Fusarium oxysporum, Alternaria alternata, and Botrytis cinerea. The reactor used in our experiments generates UV photons, electrons, ions and reactive oxygen/nitrogen species, which are highly effective as biocidal agents. The effectiveness of eliminating these fungi using DBD plasma was initially studied on artificially inoculated wooden discs and it was shown that plasma treatment for 3 min (27 ± 13) s, 5 min (32 ± 7) s, and 9 min (53 ± 30) s resulted in the destruction of 90% of F. oxysporum, A. alternata, and B. cinerea, respectively. Extending the treatment time to 20 min was sufficient to cause a lethal effect on fungi naturally contaminating the surfaces of wooden storage boxes. Plasma treatment induced damage to the cell envelope and stimulated the formation of intracellular ROS, leading to leakage of cytoplasmic contents and ultimately cell death. It was confirmed that multiple exposures of these microorganisms to plasma did not induce fungal resistance to this disinfection method.

Copper Sulfate Combined with Photodynamic Therapy Enhances Antifungal Effect by Downregulating AIF1.

Candida albicans is a clinically significant opportunistic fungus that is generally treated with antifungal drugs such as itraconazole and fluconazole. However, the recent emergence of fungal resistance has made treatment increasingly difficult. Therefore, novel antifungal treatment methods are urgently required. Hexanol ethosome photodynamic therapy (HE-PDT) is a method that uses photosensitizers (PS), such as hexanol ethosome, to exert antifungal effects, and can be used to treat resistant fungal strains. However, due to the high dose of PS required for antifungal treatment, excess photosensitizers may remain. Furthermore, once exposed to light, normal tissues or cells are damaged after photodynamic therapy, which limits the clinical application of HE-PDT. Therefore, improving the efficacy without increasing the dose is the key to this treatment. In this study, the antifungal effect of copper sulfate combined with HE-PDT was investigated, and its mechanism was explored. The results suggested that exogenous copper sulfate significantly increased the antifungal effect of HE-PDT by enhancing the rate of C. albicans inhibition, increasing reactive oxygen species (ROS) accumulation, increasing the rate of apoptosis, and altering the mitochondrial membrane potential (MMP) and ATP concentration, which is related to the downregulation of apoptosis-inducing factor (AIF1) expression. In conclusion, copper sulfate combined with photodynamic therapy significantly inhibited the activity of C. albicans by inducing apoptosis. The combined approach reported herein provides new insights for future antifungal therapy.

Analysis of the complete genome sequence of Paenibacillus sp. lzh-N1 reveals its antagonistic ability

BackgroundPlant diseases caused by pathogenic fungi are devastating. However, commonly used fungicides are harmful to the environment, and some are becoming ineffective due to fungal resistance. Therefore, eco-friendly biological methods to control pathogenic fungi are urgently needed.ResultsIn this study, a strain, Paenibacillus sp. lzh-N1, that could inhibit the growth of the pathogenic fungus Mycosphaerella sentina (Fr) Schrorter was isolated from the rhizosphere soil of pear trees, and the complete genome sequence of the strain was obtained, annotated, and analyzed to reveal the genetic foundation of its antagonistic ability. The entire genome of this strain contained a circular chromosome of 5,641,488 bp with a GC content of 45.50%. The results of species identification show that the strain belongs to the same species as P. polymyxa Sb3-1 and P. polymyxa CJX518. Sixteen secondary metabolic biosynthetic gene clusters were predicted by antiSMASH, including those of the antifungal peptides fusaricidin B and paenilarvins. In addition, biofilm formation-related genes containing two potential gene clusters for cyclic lactone autoinducer, a gene encoding S-ribosylhomocysteine lyase (LuxS), and three genes encoding exopolysaccharide biosynthesis protein were identified.ConclusionsAntifungal peptides and glucanase biosynthesized by Paenibacillus sp. lzh-N1 may be responsible for its antagonistic effect. Moreover, quorum sensing systems may influence the biocontrol activity of this strain directly or indirectly.

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.