Fungal Proteins Research Articles

Analysis of Trichoderma harzianum TR 274 secretome to assign candidate proteins involved in symbiotic interactions with Phaseolusvulgaris

Trichoderma spp can colonize host plants protecting them from pathogen infection. This association is accomplished by an exchange of molecules secreted by both the host plant and symbiotic fungus. In the present work, using LC-MS/MS analysis, our research group described a list of proteins secreted by T. harzianum TR274 during association with common bean (Phaseolus vulgaris). The main goal is to describe candidate proteins critical for the formerly mentioned association and understand mechanisms related to hosting plant tissue's colonization and modulation of bean plant defense response or metabolism. T. harzianum TR 274 could colonize common bean roots, increasing the transcript levels of defense-related genes (chit, glu1, and pal). Secretomes were obtained from culture filtrates harvested after the growth of T. harzianum TR 274 in the presence (Secretome of co-cultivation-SCC) or absence (Secretome of fungus condition-SFC) of the host plant. We identified 124 and 190 fungal proteins in SCC and SFC, respectively. A total of 30 proteins were detected only in SCC, and 94 were detected in both secretomes (SCC and SFC). The host plant presence decreases the number and diversity of proteins secreted by T. harzianum. The main functional categories represented are glycoside hydrolases, proteases, oxidoreductases, and SSCPs (Small soluble cysteine-rich secreted proteins). Our results provide a list of protein candidates for functional gene studies and validate their role in interactions between T. harzianum and P. vulgaris. Therefore, it contributes to understanding the main mechanisms of T. harzianum host plant colonization and the modulation of defense response.

Stable isotope fingerprinting traces essential amino acid assimilation and multichannel feeding in a vertebrate consumer

Abstract Animals often consume resources from multiple energy channels, thereby connecting food webs and driving trophic structure. Such ‘multichannel feeding’ can dictate ecosystem function and stability, but tools to quantify this process are lacking. Stable isotope ‘fingerprints’ are unique patterns in essential amino acid (EAA) δ13C values that vary consistently between energy channels like primary production and detritus, and they have emerged as a tool to trace energy flow in wild systems. Because animals cannot synthesize EAAs de novo and must acquire them from dietary proteins, ecologists often assume δ13C fingerprints travel through food webs unaltered. Numerous studies have used this approach to quantify energy flow and multichannel feeding in animals, but δ13C fingerprinting has never been experimentally tested in a vertebrate consumer. We tested the efficacy of δ13C fingerprinting using captive deer mice Peromyscus maniculatus raised on diets containing bacterial, fungal and plant protein, as well as a combination of all three sources. We measured the transfer of δ13C fingerprints from diet to consumer liver, muscle and bone collagen, and we used linear discriminant analysis (LDA) and isotopic mixing models to estimate dietary proportions compared to known contributions. Lastly, we tested the use of published δ13C source fingerprints previously used to estimate energy flow and multichannel feeding by consumers. We found that EAA δ13C values exhibit significant isotopic (i.e. trophic) fractionation between consumer tissues and diets. Nevertheless, LDA revealed that δ13C fingerprints are consistently routed and assimilated into consumer tissues, regardless of isotopic incorporation rate. Isotopic mixing models accurately estimated the proportional diets of consumers, but all models overestimated plant‐based protein contributions, likely due to the digestive efficiencies of protein sources. Lastly, we found that δ13C source fingerprints from published literature can lead to erroneous diet reconstruction. We show that δ13C fingerprints accurately measure energy flow to vertebrate consumers across tissues with different isotopic incorporation rates, thereby enabling the estimation of multichannel feeding at various temporal scales. Our findings illustrate the power of δ13C fingerprinting for quantifying food web dynamics, but also reveal that careful selection of dietary source data is critical to the accuracy of this emerging technique.

Effector-GAN: prediction of fungal effector proteins based on pretrained deep representation learning methods and generative adversarial networks.

Phytopathogenic fungi secrete effector proteins to subvert host defenses and facilitate infection. Systematic analysis and prediction of candidate fungal effector proteins are crucial for experimental validation and biological control of plant disease. However, two problems are still considered intractable to be solved in fungal effector prediction: one is the high-level diversity in effector sequences that increases the difficulty of protein feature learning, and the other is the class imbalance between effector and non-effector samples in the training dataset. In our study, pretrained deep representation learning methods are presented to represent multiple characteristics of sequences for predicting fungal effectors and generative adversarial networks are adapted to create synthetic feature samples to address the data imbalance problem. Compared with the state-of-the-art fungal effector prediction methods, Effector-GAN shows an overall improvement in accuracy in the independent test set. Effector-GAN offers a user-friendly interface to inspect potential fungal effector proteins (http://lab.malab.cn/~wys/webserver/Effector-GAN). The Python script can be downloaded from http://lab.malab.cn/~wys/gitlab/effector-gan. Supplementary data are available at Bioinformatics online.

GMI, a protein from Ganoderma microsporum, induces ACE2 degradation to alleviate infection of SARS-CoV-2 Spike-pseudotyped virus

BackgroundSevere Acute Respiratory Syndrome Coronavirus Type 2 (SARS-CoV-2) induces a global serious pandemic and is responsible for over 4 million human deaths. Currently, although various vaccines have been developed, humans can still get SARS-CoV-2 infection after being vaccinated. Therefore, the blocking of SARS-CoV-2 infection may be potential therapeutic strategies. Ganoderma microsporum immunomodulatory protein (GMI), a small fungal protein, is cloned from Ganoderma microsporum. It exhibits anti-cancer and immunomodulatory functions. Currently, it is still unclear whether GMI involves in interfering with viral infection. PurposeThis study aimed to examine the potential functions and mechanisms of GMI on inhibiting SARS-CoV-2 pseudovirus infection. MethodsThe effects of GMI were examined in vitro on ACE2 overexpressing HEK293T (HEK293T/ACE2) cells exposed to SARS-CoV-2 Spike lentiviral pseudovirus encoding a green fluorescent protein (GFP) gene. The infection efficacy was determined using fluorescence microscopy and flow cytometry. The protein level of ACE2 was verified by Western blot. The effects of GMI on cell viability of HEK293T/ACE2 and lung epithelial WI38–2RA cells were determined by MTT assay. Mice received GMI via nebulizer. ResultsGMI did not affect the cell viability of HEK293T/ACE2, WI38–2RA and macrophages. Functional studies showed that GMI inhibited GFP expressing SARS-CoV-2 pseudovirus from infecting HEK293T/ACE2 cells. GMI slightly interfered the interaction between ACE2 and Spike protein. GMI interacted with S2 domain of Spike protein. Specifically, GMI dramatically reduced ACE2 expression in HEK293T/ACE2 and WI38–2RA cells. Mechanistically, GMI induced ACE2 degradation via activating protein degradation system, including proteasome and lysosome. Abolishing proteasome and lysosome by MG132 and bafilomycin A1, respectively, rescued GMI-reduced ACE2 levels. In addition, GMI triggered dynamin and lipid raft-mediated ACE2 endocytosis. ACE2 levels were downregulated in the lung tissue after the mice inhaling GMI. ConclusionsGMI prevents SARS-CoV-2 pseudovirus infection via induction of ACE2 degradation in host cells. Our findings suggest that GMI will be a potential prevention agent to alleviate SARS-CoV-2 infection.

Linking the thermostability of FIP-nha (Nectria haematococca) to its structural properties

Fungal immunomodulatory proteins (FIPs) have been investigated for their use as potential natural derived anti-tumor molecules. However, the stability of FIPs is critical for their preparation and storage. In this study, the correlation between thermal stability and protein structural features of rFIP-nha, with significant anti-tumor activity, has been evaluated. For comprehensive analysis, FIP-nha and its homologues FIP-gmi, FIP-fve, and LZ-8 were all recombinantly expressed in E. coli. In solution, rFIP-nha and rFIP-gmi formed tetramers; rFIP-fve and rLZ-8 appeared as dimers. Their melting temperatures were 85.1 °C, 77.8 °C, 66.5 °C, and 64.4 °C, respectively. Accordingly, their cytotoxicity was also temperature dependent. To investigate the underlying mechanism of their thermostability, we solved the crystal structure of FIP-nha. Detailed structure analysis, molecular dynamic simulation and mutagenesis studies indicated that a higher thermostability was correlated to higher oligomerization states, larger interface area, and more interactions. The structure property studies indicate that Y12, D61 and Y108 were critical for oligomerization and high thermostability of rFIP-nha, but the dimeric and tetrameric states of rFIP-nha exert similar cytotoxicity on A549 cells. Taken together, these findings reveal that thermostability of FIPs was dependent on their oligomerization state, and correlated with their cytotoxicity.

Chemical composition and molecular docking studies of Cyamopsis tetragonoloba (L.) Taub. leaves and fruits extracts as antifungal agents against rice phytopathogenic fungi

The present study investigates the chemical composition of Cyamopsis tetragonoloba (L.) Taub. leaves and fruits extracts and their molecular docking studies as antifungal agents against rice phytopathogenic fungi. The extracts were prepared by using Soxhlet apparatus taking ethyl acetate, ethanol and methanol as solvents. These extracts were characterized by GC-MS analysis and were evaluated for their antifungal potential against Rhizoctonia solani and Drechslera oryzae. Maximum antifungal activity was shown by ethyl acetate fruits extract with minimum EC50 values. All the major compounds in guar extracts were subjected to molecular docking studies against the fungal target protein, i.e. lanosterol 14α- demethylase to find their potential binding mode and binding affinity. Among the six compounds, stigmasterol and γ-sitosterol bound most strongly with the receptor through the involvement of single-residue interactions. Hence, both these sterols present in ethyl acetate fruits extract can be effectively used to control these phytopathogenic fungi.

The Identification and Characterization of Immunoreactive Fungal Proteins Recognized by Sera from Zimbabweans Sensitized to Fungi

Background: Exposure to fungal allergens poses a serious threat to human health, especially to mould-allergic individuals. The prevalence of fungal allergic disease is increasing globally but is poorly studied in Africa. Here, we aimed to identify and characterize fungal proteins that were immunoreactive against serum samples from fungal-sensitized Zimbabweans from Shamva district to inform the development of diagnostics and therapeutics. Methods: Crude protein extracts of the Ascomycota Aspergillus fumigatus, Alternaria alternata, Cladosporium herbarum, Epicoccum nigrum, Penicillium chrysogenum, and Saccharomyces cerevisiae as well as mucoromycota Rhizopus nigricans were individually separated by one-dimensional gel electrophoresis for protein staining and immunoblotting. A pool of eight sera from fungi-sensitive Zimbabwean children aged 3–5 years was used to screen the crude extracts to determine their immunoreactivity. Protein bands recognized by the sera were subjected to mass spectrometry to identify the individual proteins reactive with the sera. Results: The pooled serum sample reacted with 20 bands, which resolved to 34 distinct proteins, most of which were novel immunogens. The pool was most reactive to A. alternata. The proteins identified included peptidases (8/34), hydrolases (6/34), oxidoreductases (5/34), and glucosidases (4/34), while 11/34 were unknown. Eight of the proteins were predicted to be allergens using the Structural Database of Allergenic Proteins (SDAP). Conclusions: We identified novel immunogens from fungi expanding the number of known fungal allergens. These form a potential basis for diagnostics specific for the Zimbabwean population. Validation assays will now need to be carried out to further evaluate the cross-reactivity of the identified allergen candidates as well as investigate their potential recognition in a larger cohort of patients. Furthermore, there is now a need to conduct studies relating sensitization to these immunogens and clinical diseases in the population.

T-cell epitope-based vaccine prediction against Aspergillus fumigatus: a harmful causative agent of aspergillosis

BackgroundAmong the most common causes of invasive aspergillosis and acute bronchopulmonary aspergillosis is Aspergillus fumigatus. Transmission with A. fumigatus produces aggressive aspergillosis in allogeneic haematopoietic stem cell transplant recipients, HIV patients, and cancer patients. Asthmatics and cystic fibrosis patients are allergic to A. fumigatus. MHC class-II binding epitopes can initiate immunogenic responses in patients. In this study, we deployed immunoinformatic study to reveal epitopes from fungal proteins. ResultsIn modern research, we found multiple epitopes ITLKLLHRYSYKLAG, KLVLRAFPNHFRGDS, RYSYKLAGVNQVDVV, GKSFELNQAARAVTQ, and LHRYSYKLAGVNQVD from crucial proteins of A. fumigatus 5,8-linoleate diol synthase (ACO55067.2) and ChainB-chitinase A1 (2XVN_B). RYSYKLAGVNQVDVV, GKSFELNQAARAVTQ, and LHRYSYKLAGVNQVD epitopes interact with HLA-DRB01_0101, while ITLKLLHRYSYKLAG and KLVLRAFPNHFRGDS epitopes interact with HLA-DRB01_1501. Molecular docking analysis reveals atomic contact energy (ACE) value for these five epitopes shown below −5 Kcal/mol in docked state. ConclusionsThe invasive aspergillosis and acute bronchopulmonary aspergillosis are caused by harmful fungal pathogen Aspergillus fumigatus. Our modern immunoinformatic research shows ITLKLLHRYSYKLAG, KLVLRAFPNHFRGDS, RYSYKLAGVNQVDVV, GKSFELNQAARAVTQ, and LHRYSYKLAGVNQVD epitopes could bind to MHC-II HLA allelic determinants and can initiate immunogenic response in patients affected by Aspergillus fumigatus.

FIP-fve Stimulates Cell Proliferation and Enhances IL-2 Release by Activating MAP2K3/p38α (MAPK14) Signaling Pathway in Jurkat E6-1 Cells.

FIP-fve, a fungal fruiting body protein from Flammulina velutipes, has potential immunomodulatory properties. Here, we investigated the immunomodulation mechanism of FIP-fve in Jurkat E6-1 cells by conducting a cell viability assay and IL-2 release assay. Kinase inhibitors experiment and proteomics analysis were also involved in the mechanism study. It was found that FIP-fve stimulated cell proliferation and enhanced IL-2 secretion in a dose-dependent manner in Jurkat E6-1 cells. Unbiased high-throughput proteomics analysis showed that 4 T cell immune activation markers, including ZAP-70, CD69, CD82, and KIF23, were upregulated in response to FIP-fve treatment. Further pathway analysis indicated that MAP2K3/p38 pathway-related proteins, including MAP2K, p38, ELK, AATF, FOS, and JUN-B, were unregulated. In addition, losmapimod (p38 inhibitor) and gossypetin (MAP2K3 inhibitor) inhibited FIP-fve enhanced cell proliferation and IL-2 release in Jurkat E6-1 cells. Our results demonstrate that FIP-fve stimulates cell proliferation and enhances IL-2 secretion through MAP2K3/p38α activation.

Systematic contributions of CFEM domain-containing proteins to iron acquisition are essential for interspecies interaction of the filamentous pathogenic fungus Beauveria bassiana.

Common in fungal extracellular membrane (CFEM) domain is unique in fungal proteins and some of which contribute to iron acquisition in yeast. However, their roles in iron acquisition remain largely unknown in filamentous fungi. In this study, 12 CFEM-containing proteins were bioinformatically identified in the filamentous entomopathogenic fungus Beauveria bassiana, and the roles of 11 genes were genetically characterized. Transmembrane helices were critical for their association with intracellular membranes, and their number varied among proteins. Eleven CFEM genes significantly contribute to vegetative growth under iron starvation and virulence. Notably, the virulence of most disruptants could be significantly weakened by a decrease in iron availability, in which the virulence of ΔBbcfem7 and 8 strains was partially recovered by exogenous hemin. ΔBbcfem7 and 8 mutants displayed defective competitiveness against the sister entomopathogenic fungus Beauveria brongniartii. All 11 disruptants displayed impaired growth in the antagonistic assay with the saprotrophic fungus Aspergillus niger, which could be repressed by exogenous ferric ions. These findings not only reveal the systematic contributions of CFEM proteins to acquire two forms of iron (i.e. heme and ferric ion) in the entire lifecycle of entomopathogenic fungi but also help to better understand the mechanisms of fungus-host and inter-fungus interactions.

The Velvet Protein UvVEA Regulates Conidiation and Chlamydospore Formation in Ustilaginoidea virens.

Rice false smut, caused by Ustilaginoidea virens, is a serious disease of rice worldwide, severely reducing the quantity and quality of rice production. The conserved fungal velvet proteins are global regulators of diverse cellular processes. We identified and functionally characterized two velvet genes, UvVEA and UvVELB, in U. virens. The deletion of these genes affected the conidiation of U. virens but had no effect on the virulence of this pathogen. Interestingly, the ΔUvVEA mutants appeared in the form of smaller false smut balls with a reduced number of chlamydospores compared with the wide-type strains. In addition, the deletion of UvVEA affected the expression of some transmembrane transport genes during chlamydospore formation and rice false smut balls development. Furthermore, the ΔUvVEA mutants were shown to be defective in the utilization of glucose. These findings proved the regulatory mechanism underlying the formation of rice false smut balls and chlamydospores and provided a basis for the further exploration of the mechanism of these processes.

New strategies for combating fungal infections: Inhibiting inositol lipid signaling by targeting Sec14 phosphatidylinositol transfer proteins.

Virulent fungi represent a particularly difficult problem in the infectious disease arena as these organisms are eukaryotes that share many orthologous activities with their human hosts. The fact that these activities are often catalyzed by conserved proteins places additional demands on development of pharmacological strategies for specifically inhibiting target fungal activities without imposing undesirable secondary effects on the host. While deployment of a limited set of anti-mycotics has to date satisfied the clinical needs for treatment of fungal infections, the recent emergence of multi-drug resistant fungal 'superbugs' now poses a serious global health threat with rapidly diminishing options for treatment. This escalating infectious disease problem emphasizes the urgent need for development of new classes of anti-mycotics. In that regard, Sec14 phosphatidylinositol transfer proteins offer interesting possibilities for interfering with fungal phosphoinositide signaling with exquisite specificity and without targeting the highly conserved lipid kinases responsible for phosphoinositide production. Herein, we review the establishment of proof-of-principle that demonstrates the feasibility of such an approach. We also describe the lead compounds of four chemotypes that directly target fungal Sec14 proteins. The rules that pertain to the mechanism(s) of Sec14 inhibition by validated small molecule inhibitors, and the open questions that remain, are discussed - as are the challenges that face development of next generation Sec14-directed inhibitors.

Cocaprins, β-Trefoil Fold Inhibitors of Cysteine and Aspartic Proteases from Coprinopsis cinerea.

We introduce a new family of fungal protease inhibitors with β-trefoil fold from the mushroom Coprinopsis cinerea, named cocaprins, which inhibit both cysteine and aspartic proteases. Two cocaprin-encoding genes are differentially expressed in fungal tissues. One is highly transcribed in vegetative mycelium and the other in the stipes of mature fruiting bodies. Cocaprins are small proteins (15 kDa) with acidic isoelectric points that form dimers. The three-dimensional structure of cocaprin 1 showed similarity to fungal β-trefoil lectins. Cocaprins inhibit plant C1 family cysteine proteases with Ki in the micromolar range, but do not inhibit the C13 family protease legumain, which distinguishes them from mycocypins. Cocaprins also inhibit the aspartic protease pepsin with Ki in the low micromolar range. Mutagenesis revealed that the β2-β3 loop is involved in the inhibition of cysteine proteases and that the inhibitory reactive sites for aspartic and cysteine proteases are located at different positions on the protein. Their biological function is thought to be the regulation of endogenous proteolytic activities or in defense against fungal antagonists. Cocaprins are the first characterized aspartic protease inhibitors with β-trefoil fold from fungi, and demonstrate the incredible plasticity of loop functionalization in fungal proteins with β-trefoil fold.

Factors affecting consumer attitudes to fungi-based protein: A pilot study

Meat substitutes using alternative proteins can facilitate sustainable diets without compromising animal welfare. The fungal protein, also called mycoprotein is the biomass that results from the fermentation of a filamentous fungus. This paper reports the results of a consumer acceptance study of fungal protein-based meat substitutes using a mixed-method design with a web-based survey and a series of semi-structured interviews amongst European participants. Based on the description provided in the survey, 56% of participants were not directly familiar with fungal proteins but they understood its potential societal benefits. The overall Food Technology Neophobia Score (FTNS) of the sample was moderate (M = 40.0, range = 19–62), with more neophilic participants (52.9%) than neophobic (47.1%). FTN was a significant but weak predictor of Perceived Benefits (PB) and Purchase Intentions (PI). Younger participants perceived fungal proteins more positively, and city-dwellers had higher PI than rural dwellers. Reducetarians were more likely to purchase fungal proteins, compared to unrestricted omnivores. Participants with lower acceptance of fungal proteins’ association with mould had significantly lower PI than those who were comfortable with it. In turn, familiarity with fungal protein was positively associated with mould acceptance. The qualitative data suggested that the sensory attributes were the most important factor in the acceptance of meat substitutes. The participants also valued clean label products which were perceived as healthier. Familiarity with other products containing mould seemed to assuage concerns and drive acceptance of fungal protein. The findings suggest that the overall acceptance of fungal protein is still rather low. This may be attributed to the perceived low appeal and tastiness of available fungal protein products.

Efficacy of GMI, a fungal immunomodulatory protein, for head and neck cancer patients with chemotherapy-related oral mucositis: An open-labeled prospective single-arm study.

Background:Cancer patients usually suffer from intensive chemotherapy-related oral mucositis (OM), yet limited effective treatment can rapidly alleviate OM severity.Methods:This prospective study examined the efficacy of Reishimmune-S containing one fungal immunomodulatory protein, GMI on OM in patients with head and neck cancer. Patients with head and neck cancer and the diagnosis of chemotherapy-related OM were enrolled randomizedly to receive standard supportive care with/without Reishimmune-S 500 mg/day orally for consecutive 14 days. Due to intolerance to standard supportive care alone in the control arm, only the experimental arm with Reishimmune-S supplementation was analyzed in our trial. OM grading was evaluated as the primary outcome on day 1, 8, and 15. Secondary outcomes were absolute neutrophil counts and quality of life assessed by the EORTC-QLQ-H&N 35 questionnaire on day 1, 8, and 15.Results:Reishimmune-S supplement significantly reduced OM grading both at day 8 and 15. Trouble with social contact and weight loss conditions were also improved by Reishimmune-S. Reishimmune-S did not significantly affect absolute neutrophil counts during the 15-day follow-up.Conclusion:Reishimmune-S supplement potentially alleviates the severity of chemotherapy-mediated OM.

Impairment of the cellulose degradation machinery enhances Fusarium oxysporum virulence but limits its reproductive fitness.

Fungal pathogens grow in the apoplastic space, in constant contact with the plant cell wall (CW) that hinders microbe progression while representing a source of nutrients. Although numerous fungal CW modifying proteins have been identified, their role during host colonization remains underexplored. Here, we show that the root-infecting plant pathogen Fusarium oxysporum (Fo) does not require its complete arsenal of cellulases to infect the host plant. Quite the opposite: Fo mutants impaired in cellulose degradation become hypervirulent by enhancing the secretion of virulence factors. On the other hand, the reduction in cellulase activity had a severe negative effect on saprophytic growth and microconidia production during the final stages of the Fo infection cycle. These findings enhance our understanding of the function of plant CW degradation on the outcome of host-microbe interactions and reveal an unexpected role of cellulose degradation in a pathogen’s reproductive success.

Computational identification and characterization of vascular wilt pathogen (Fusarium oxysporum f. sp. lycopersici) CAZymes in tomato xylem sap

Fusarium oxysporum f. sp. lycopersici is a devastating plant pathogenic fungi known for wilt disease in the tomato plant and secrete cell wall degrading enzymes. These enzymes are collectively known as carbohydrate-active enzymes (CAZymes), crucial for growth, colonization and pathogenesis. Therefore, the present study was aimed to identify and annotate pathogen CAZymes in the xylem sap of a susceptible tomato variety using downstream proteomics and meta servers. Further, structural elucidation and conformational stability analysis of the selected CAZyme families were done through homology modeling and molecular dynamics simulation. Among all the fungal proteins identified, the carbohydrate metabolic process was found to be enriched. Most of the annotated CAZymes belonged to the hydrolase and oxidoreductase families, and 90% were soluble and extracellular. Moreover, using a publically available interactome database, interactions were observed between the families acting on chitin, hemicellulose and pectin. Subsequently, important catalytic residues were identified in the candidate CAZymes belonging to carbohydrate esterase (CE8) and glycosyl hydrolase (GH18 and GH28). Further, essential dynamics after molecular simulation of 100 ns revealed the overall behavior of these CAZymes with distinct global minima and transition states in CE8. Thus, our study identified some of the CAZyme families that assist in pathogenesis and growth through host cell wall deconstruction with further structural insight into the selected CAZyme families. Communicated by Ramaswamy H. Sarma

Inactivation of Escherichia coli Using Biogenic Silver Nanoparticles and Ultraviolet (UV) Radiation in Water Disinfection Processes

This work tested the antimicrobial activity of three different biogenic silver nanoparticles (AgNPs) against Escherichia coli (E. coli) for water disinfection processes. The influence of different AgNP capping or stabilizing agents (e.g., protein or carbohydrate capped) and the use of ultraviolet (UV) radiation on the disinfection process were also assessed. The use of UV radiation was found to enhance the antimicrobial effects of AgNPs on E. coli. The antibacterial effects of AgNPs depended on the type of the capping biomolecules. Protein-capped nanoparticles showed greater antimicrobial effects compared with carbohydrate-capped (cellulose nanofibers, CNF) nanoparticles. Those capped with the fungal secretome proteins were the most active in E. coli inactivation. The least E. coli inactivation was observed for CNF-capped AgNPs. The size of the tested AgNPs also showed an expected effect on their anti-E. coli activity, with the smallest particles being the most active. The antimicrobial effects of biogenic AgNPs on E. coli make them an effective, innovative, and eco-friendly alternative for water disinfection processes, which supports further research into their use in developing sustainable water treatment processes.

Adhesion as a Focus in Trichoderma-Root Interactions.

Fungal spores, germlings, and mycelia adhere to substrates, including host tissues. The adhesive forces depend on the substrate and on the adhesins, the fungal cell surface proteins. Attachment is often a prerequisite for the invasion of the host, hence its importance. Adhesion visibly precedes colonization of root surfaces and outer cortex layers, but little is known about the molecular details. We propose that by starting from what is already known from other fungi, including yeast and other filamentous pathogens and symbionts, the mechanism and function of Trichoderma adhesion will become accessible. There is a sequence, and perhaps functional, homology to other rhizosphere-competent Sordariomycetes. Specifically, Verticillium dahliae is a soil-borne pathogen that establishes itself in the xylem and causes destructive wilt disease. Metarhizium species are best-known as insect pathogens with biocontrol potential, but they also colonize roots. Verticillium orthologs of the yeast Flo8 transcription factor, Som1, and several other relevant genes are already under study for their roles in adhesion. Metarhizium encodes relevant adhesins. Trichoderma virens encodes homologs of Som1, as well as adhesin candidates. These genes should provide exciting leads toward the first step in the establishment of beneficial interactions with roots in the rhizosphere.

Secretome Analysis of Macrophomina phaseolina Identifies an Array of Putative Virulence Factors Responsible for Charcoal Rot Disease in Plants.

Macrophomina phaseolina is a global devastating necrotrophic fungal pathogen. It causes charcoal rot disease in more than 500 host plants including major food crops, pulse crops, fiber crops, and oil crops. Despite having the whole-genome sequence of M. phaseolina, understanding the M. phaseolina genome-based plant–pathogen interactions is limited in the absence of direct experimental proof of secretion. Thus, it is essential to understand the host–microbe interaction and the disease pathogenesis, which can ensure global agricultural crop production and security. An in silico–predicted secretome of M. phaseolina is unable to represent the actual secretome. We could identify 117 proteins present in the secretome of M. phaseolina using liquid chromatography–electrospray ionization–tandem mass spectrometry. Data are available via ProteomeXchange with identifier PXD032749. An array of putative virulence factors of M. phaseolina were identified in the present study using solid-state culture. Similar virulence factors have been reported in other plant pathogenic fungi also. Among the secretory fungal proteins with positive economic impacts, lignocellulolytic enzymes are of prime importance. Further, we validated our results by detecting the cell wall–degrading enzymes xylanase, endoglucanase, and amylase in the secretome of M. phaseolina. The present study may provide a better understanding about the necrotrophic fungi M. phaseolina, which modulate the host plant defense barriers using secretory proteins.