Endophytic Fungal Strains Research Articles

Growth Stimulation, Phosphate Resolution, and Resistance to Fungal Pathogens of Some Endogenous Fungal Strains in the Rhizospheres of Medicinal Plants in Vietnam.

Endophytic fungi are recognized for their many potential applications in agriculture, such as supporting cropland expansion and increasing the yield and resistance of plants by creating antibiotics that inhibit the growth of pathogenic microorganisms. In addition, they can produce enzymes that break down hard-to-solubilize substances within soil, dissolve phosphates, fix nitrogen, reduce metals, and produce hormones that promote plant growth (auxin, cytokinin, and gibberellins) to keep crops healthy. In this report, three strains of endophytic fungi, namely, N1, N2, and N3, were isolated from the roots of Stevia rebaudiana (Bert.) Hemsl., Polyscias fruticosa, and Angelica dahurica in some localities in Vietnam. Through a screening process, it was found that they can produce high levels of indole acetic acid (IAA), resolve phosphates, and resist disease, and they were selected to as an alternative to chemical fertilizers to make probiotics in order to increase medicinal plant yields. The results show that the three strains of fungi have the ability to degrade phosphate to 341.90, 1498.46, and 390.79 ppm; the content of IAA produced in the culture medium reached 49.00, 52.35, and 33.34 ppm. Based on some morphological characteristics and an internal transcribed spacer gene sequence analysis of the fungal strains, N1, N2, and N3 were named Penicillium simplicissimum CN7, Talaromyces flavus BC1, and Trichoderma konilangbra DL3, respectively, which have the ability to inhibit the growth of pathogenic fungal strains, such as fungus C. gloeosporioides (CD1), fungus F. oxysporum, fungus L. theobromae N13, and N. dimidiatum. They grow significantly over a period of 5 to 6 days.

Diversity of endophytic fungal community in Huperzia serrata from different ecological areas and their correlation with Hup A content

BackgroundHuperzine A (Hup A) has attracted considerable attention as an effective therapeutic candidate drug used to treat Alzheimer’s disease. Whereas, the production of Hup A from wild plants faced a major challenge, which is the wild Huperzia Serrata harbor a low Hup A content, has a long-life cycle, and has a small yield. At present, several reports showed that Hup A is produced by various endophytic fungal strains isolated from H. serrata, thereby providing an alternative method to produce the compound and reduce the consumption of this rare and endangered plant. However, till now, very few comprehensive studies are available on the biological diversity and structural composition of endophytic fungi and the effects of endophytic fungi on the Hup A accumulation in H. serrata.ResultsIn this research, the composition and diversity of fungal communities in H. serrata were deciphered based on high-throughput sequencing technology of fungal internal transcribed spacer regions2 (ITS2). The correlation between endophytic fungal community and Hup A content was also investigated. Results revealed that the richness and the diversity of endophytic fungi in H. serrata was various according to different tissues and different ecological areas. The endophytic fungal communities of H. serrata exhibit species-specific, ecological-specific, and tissue-specific characteristics. There are 6 genera (Ascomycota_unclassified, Cyphellophora, Fungi_unclassified, Sporobolomyces, and Trichomeriaceae_unclassified) were significantly positively correlated with Hup A content in all two areas, whereas, there are 6 genera (Auricularia, Cladophialophora, Cryptococcus, Mortierella, and Mycena) were significantly negatively correlated with Hup A content of in all two areas.ConclusionsThis study indicated a different composition and diverse endophytic fungal communities in H. serrata from different organs and ecological areas. The current study will provide the realistic basis and theoretical significance for understanding the biological diversity and structural composition of endophytic fungal communities in H. serrata, as well as providing novel insights into the interaction between endophytic fungi and Hup A content.

Light enhanced the antimicrobial, anticancer, and catalytic activities of selenium nanoparticles fabricated by endophytic fungal strain, Penicillium crustosum EP-1

Selenium nanoparticles (Se-NPs) has recently received great attention over owing to their superior optical properties and wide biological and biomedical applications. Herein, crystallographic and dispersed spherical Se-NPs were green synthesized using endophytic fungal strain, Penicillium crustosum EP-1. The antimicrobial, anticancer, and catalytic activities of biosynthesized Se-NPs were investigated under dark and light (using Halogen tungsten lamp, 100 Watt, λ > 420 nm, and light intensity of 2.87 W m−2) conditions. The effect of Se-NPs was dose dependent and higher activities against Gram-positive and Gram-negative bacteria as well different Candida spp. were attained in the presence of light than obtained under dark conditions. Moreover, the viabilities of two cancer cells (T47D and HepG2) were highly decreased from 95.8 ± 2.9% and 93.4 ± 3.2% in dark than those of 84.8 ± 2.9% and 46.4 ± 3.3% under light-irradiation conditions, respectively. Significant decreases in IC50 values of Se-NPs against T47D and HepG2 were obtained at 109.1 ± 3.8 and 70.4 ± 2.5 µg mL−1, respectively in dark conditions than 19.7 ± 7.2 and 4.8 ± 4.2 µg mL−1, respectively after exposure to light-irradiation. The photoluminescence activity of Se-NPs revealed methylene blue degradation efficiency of 89.1 ± 2.1% after 210 min under UV-irradiation compared to 59.7 ± 0.2% and 68.1 ± 1.03% in dark and light conditions, respectively. Moreover, superior stability and efficient MB degradation efficiency were successfully achieved for at least five cycles.

Endophytic Fungi Associated with Coffee Leaves in China Exhibited In Vitro Antagonism against Fungal and Bacterial Pathogens.

Coffee endophytes have been studied for almost 74 years, and several studies have demonstrated coffee-endophytic fungi with antibacterial and antifungal potential for human and plant pathogens. In this study, we isolated and identified a total of 235 strains of endophytic fungi from coffee leaf tissues collected in four coffee plantations in Pu’er city, Yunnan province, China. Molecular identification was carried out using maximum likelihood phylogenetic analysis of nuclear ribosomal internal transcribed spacer (ITS1-5.8S rDNA-ITS2) sequences, while the colonization rate and the isolation frequency were also calculated. Two pathogenic fungi (Alternaria alternata and Penicillium digitatum) and two pathogenic bacteria (Pseudomonas syringae and Salmonella enterica subsp. enterica) were used for screening the antagonistic activities of 61 strains of coffee-endophytic fungi by a dual-culture test assay while maximum likelihood phylogenetic analysis confirmed their natural classification. This is the first study of coffee-leaf-endophytic fungal diversity in China, and the results revealed that coffee-endophytic fungi from this study belong to the Ascomycota, distributed among two classes, 10 orders, and 17 families. Concurrently, endophytic fungi isolates distributed in Arthrinium, Biscogniauxia, Daldinia, Diaporthe, and Nigrospora showed strong antagonistic activities against the pathogens. For the pathogens Alternaria alternata and Pseudomonas syringae, Nigrospora XCE-7 showed the best inhibitory effects with inhibition rates of 71.76% and 61.11%, respectively. For the pathogen Penicillium digitatum, Daldinia ME-9 showed the best inhibitory effect with a 74.67% inhibition rate, while Biscogniauxia PTE-7 and Daldinia T5E-1-3 showed the best inhibitory effect with a rate of 60.42% against the pathogen Salmonella enterica subsp. enterica. Overall, our study shows the diversity of coffee endophytes in four coffee-growing areas in Pu’er city, Yunnan province, China, and their potential use as biological control agents against two fungal and two bacterial pathogens.

Diversity and Antibacterial and Antioxidant Activities of Fungal Endophytes from the Roots of Eucalyptus deglupta

In this study, 45 endophytic fungal strains were isolated from the roots of Eucalyptus deglupta. Among them, 16 distinct strains were identified and classified into 14 different genera (Celoporthe, Aspergillus, Castanediella, Chaetomium, Biscogniauxia, Sordariales, Pestalotiopsis, Clitopilus, Cylindrocladiella, Calonectria, Trichoderma, Xylaria, Neofusicoccum and Pleosporales) according to their morphological characteristics and molecular information. The genera Aspergillus and Calonectria were the dominant endophytic fungi in the roots of E. deglupta. In addition, the antibacterial and antioxidant activities of the 16 endophytic fungi isolated from the roots of E. deglupta were evaluated. All the strains displayed inhibitory activities against Agrobacterium tumefaciens, Bacillus subtilis, Escherichia coli, and Xanthomonas vesicatoria. Strains Edf-1 to Edf-4, Edf-11 and Edf-12 demonstrated strong inhibitory activity against R. solanacearum with plaque diameters between 5 and 10 mm. The crude extract of Edf-14 had inhibitory activity against all tested bacteria. Five strains, Edf-1 to Edf-5, demonstrated a strong scavenging capacity for 2,2-diphenyl-1-picrylhydrazyl (DPPH), with IC50 values of 0.26 ± 0.04, 0.11 ± 0.03, 0.20 ± 0.05, 0.10 ± 0.04 and 0.14 ± 0.02 mg/mL, respectively. Hence, endophytic fungi isolated from the roots of E. deglupta showed antibacterial and antioxidant activities, providing a theoretical foundation for further isolation and identification of specific active components.

Exploring the potential of benzoic acid derived from the endophytic fungus strain Neurospora crassa SSN01 as a promising antimicrobial agent in wound healing

Endophytic fungi are known to produce bioactive compounds with the potential to be used as promising drugs to treat a wide range of diseases. To the best of our knowledge, the use of bioactive metabolites derived from endophytic fungi, particularly against multidrug resistant (MDR) pathogens inhabiting burn wounds, has been emphasized for the first time. Therefore, the purpose of this study is to investigate the potential of purified benzoic acid (BA) derived from Neurospora crassa, an endophytic fungus isolated from Lycium shawii, as a promising and alternative safe antimicrobial candidate in wound healing. As a result, benzoic acid, a safe and nontoxic compound, may be a promising candidate for combating clinical MDR pathogens of burn wound infections. In this study, Neurospora crassa strain SSN01 (MW856826) was successfully identified for the first time as a new BA-producing endophytic fungus isolated from Lycium shawii. The concentration of BA in the ethyl acetate extract reached 244 mg/mL. Purified BA had a detrimental effect on the MDR strains tested, and the MDR Staphylococcus aureus strain SA-17 was clearly more susceptible to BA as compared to the other tested MDR bacterial and fungal strains. Toxicological studies on experimental animals were conducted to evaluate the toxicity of BA and a suitable dose regimen for future human use. Oral administration of BA at the highest concentration of 300 µg/kg body weight resulted in nontoxic signs and no mortality. In vivo histopathological examination revealed that BA, as a nontoxic and safe compound, could be a promising candidate for wound healing, combating MDR pathogens of burn wound infections.

Diversity and importance of culturable endophytic fungi of tobacco (Nicotinana tabacum) cultivated in southwestern China

AbstractTobacco (Nicotiana tabacum) is one of the most important economic crops in China; however, black shank caused by Phytophthora parasitica is major threat to its cultivation. So far, little is known regarding potential antagonistic effects of endophytes on plant pathogens. A total of 109 culturable endophytic fungal strains were recovered from various tissues of six tobacco cultivars that are commonly cultivated in southwestern China. Morphological and molecular identification showed that these isolates belonged to 18 different genera, including Aspergillus, Chaetomium, Gibellulopsis and Penicillium as predominant genera, which were frequently observed in stem, leaf and root tissues. Among them, only 17 endophytic fungal strains exerted antagonistic effects on P. parasitica in the dual‐culture test, and the highest inhibition rate of 73% was produced by a Penicillium janthinellum strain isolated from stem tissue of a cultivar HD. Nevertheless, a field trial revealed that Shannon–Wiener indices were negatively correlated with the disease index and with the incidence of tobacco blank shank in cultivars K326, YUN85, D101 and GUI1, which was further supported by the evaluation of endophytic community similarity. Our results contribute to the understanding of functions and diversity of endophytic fungi, and culturable endophytic fungal strains may be considered potential libraries for screening novel bioactive and effective metabolites to control P. parasitica in crops which requires further research.

Metabolites of zearalenone and phytohormones secreted by endophytic fungus strain TH15 regulating the root development in Tetrastigma hemsleyanum

Metabolites of zearalenone and phytohormones secreted by endophytic fungus strain TH15 regulating the root development in Tetrastigma hemsleyanum

Enhanced Production, Cloning, and Expression of a Xylanase Gene from Endophytic Fungal Strain Trichoderma harzianum kj831197.1: Unveiling the In Vitro Anti-Fungal Activity against Phytopathogenic Fungi.

Trichoderma sp. is extensively applied as a beneficial fungus for the management of plant diseases, plant growth promotion, induced resistance, and plays an important role in global sustainable agriculture. This study aimed to enhance the production of microbial xylanase in high titer from the endophytic fungus Trichoderma harzianum kj831197.1, and the cloning of xylanase genes in E. coli DH5α using a pUC19 vector. A combination of glucose, 0.1 mM, Tween 80 with lactose, and 2 mM galactose combined with malt extract boostedthe enzyme production. Xylanase production was maximized at a pH of 5.0, temp. of 30 °C, and agitation of 150 rpm in the presence of malt extract and bagasse as the best nitrogen source and waste, respectively, using submerged fermentation. The molecular weight of highly purified xylanase was 32 KDa, identified using SDS-PAGE. The xylanase gene of T. harzianum kj831197.1 was screened in fungal DNA using definite primers specified in the gene bank database. The identified region was excised using restriction enzymes HindIII and EcoRI and cloned into a pUC19 plasmid vector. Optimization of fermentation conditions improved xylanase production about 23.9-fold.The antifungal efficacy of xylanase toward different phytopathogenic fungi was determined. The highest inhibition was against Corynespora cassiicola, Alternaria sp., Fusarium oxysporum, and Botrytis fabae. This study offered an economical, simple, and efficient method using Trichoderma harzianum kj831197.1 for the production of the xylanase enzyme via the submerged fermentation method.

Diversity and Biosynthetic Activities of Agarwood Associated Fungi

Agarwood is a fragrant dark resin produced in plants belonging to the family Thyme-laeaceae and which has a high economic value. The unique fragrance and medicinal applications intensify the value of agarwood. The wild populations of agarwood trees are highly threatened by high economic demand. Therefore, it is worthwhile to develop an artificial agarwood induction technology for the countries that rely on agarwood from the natural habitat of the plants. Fungal induction of agarwood has been shown to be an efficient method. Interestingly, most of the fungi known from agarwood are endophytic. In this paper, we supplement and update the bioactivity of fungi associated with agarwood and their ability to induce agarwood formation. According to the existing literature, 59 endophytic fungal strains of 16 genera induce agarwood production, most of which belong to Fusarium (28 identified strains). Hence, Fusarium is a good candidate for further studies on fungal induced agarwood production.

Micobiota endófita asociada a plantas de Vaccinium corymbosum L. en el valle Cañete- Perú

Endophytic fungi (EF) are microorganisms that live asymptomatically within plant tissues. They can confer benefits to the plant as inducers of resistance to pests and diseases, tolerance to abiotic factors, plant growth promoters and mycoparasites of pathogens. This study aimed to isolate, identify, and determine occurrence frequency of endophytic fungi in stems and leaves of blueberry plants collected from ten farms in Lima and Ica Region, Peru. Productive branches of 39 healthy plants were sampled. For the isolation of EF, 702 tissue sections were disinfected and transferred to Petri dishes with potato dextrose agar (PDA) medium, and reproductive structures were induced for identification. A total of 134 EF strains were isolated successfully. Nine genera were identified (Trichoderma, Aspergillus, Alternaria, Ulocladium, Cladosporium, Fusarium, Nigrospora, Lasiodiplodia and Stemphylium). EF occurrence frequency varied greatly between organs, being in leaves more frequent than the stems; likewise, the genera Alternaria and Cladosporium were the most frequent and with most colonized in plant tissues, while Aspergillus, Ulocladium and Lasiodiplodia were the least frequent. These strains could be useful to control plant diseases and, therefore, of great interest in sustainable agriculture.

Chemical modulation of the metabolism of an endophytic fungal strain of Cophinforma mamane using epigenetic modifiers and amino-acids

Endophytic fungi are capable of producing a great diversity of bioactive metabolites. However, the presence of silent and lowly expressed genes represents a main challenge for the discovery of novel secondary metabolites with different potential uses. Epigenetic modifiers have shown to perturb the production of fungal metabolites through the induction of silent biosynthetic pathways leading to an enhanced chemical diversity. Moreover, the addition of bioprecursors to the culture medium has been described as a useful strategy to induce specific biosynthetic pathways. The aim of this study was to assess the effects of different chemical modulators on the metabolic profiles of an endophytic fungal strain of Cophinforma mamane (Botryosphaeriaceae), known to produce 3 thiodiketopiperazine (TDKP) alkaloids (botryosulfuranols A-C), previously isolated and characterized by our team. Four epigenetic modifiers, 5-azacytidine (AZA), sodium butyrate (SB), nicotinamide (NIC), homoserine lactone (HSL) as well as 2 amino acids, l-phenylalanine and l-tryptophan, as bioprecursors of TDKPs, were used. The metabolic profiles were analysed by UHPLC-HRMS/MS under an untargeted metabolomics approach. Our results show that the addition of the two amino acids in C. mamane culture and the treatment with AZA significantly reduced the production of the TDKPs botryosulfuranols A, B and C. Interestingly, the treatment with HSL significantly induced the production of different classes of diketopiperazines (DKPs). The treatment with AZA resulted as the most effective epigenetic modifier for the alteration of the secondary metabolite profile of C. mamane by promoting the expression of cryptic genes.

A New Source of Diterpene Lactones From Andrographis paniculata (Burm. f.) Nees-Two Endophytic Fungi of Colletotrichum sp. With Antibacterial and Antioxidant Activities.

Endophytic fungi of medicinal plants are abundant, and their metabolites often have antioxidant, antibacterial, and antitumor effects and can produce secondary metabolites identical or similar to those of their hosts, which can mitigate the problem of insufficient supply of medicinal plants. In this study, we screened endophytic fungi for strains that produce the same diterpene lactones as Andrographis paniculata based on their biological activity. Firstly, the dominant group of endophytic fungi of Andrographis paniculata was screened and pathogenicity was studied using Koch’s rule. Secondly, DPPH, ABTS, OH, PTIO radical scavenging, and FRAP assays were used to detect the antioxidant activity of the extracellular extracts of the strains, and total phenol and total flavonoid contents of the strains with high antioxidant capacity were determined. S. aureus, B. subtilis, E. coli, and P. aeruginosa were used to determine the antibacterial activity of the mycelial extracts of the strains. Finally, the secondary metabolites of the mycelial extracts of the strains were examined by high-performance liquid chromatography. The results showed that 32 strains of Andrographis paniculata were relatively isolated > 70% and non-pathogenic. Extracellular extracts of strains AP-1 and AP-4 showed vigorous antioxidant activity, and AP-4, AP-12, AP-47, and AP-48 showed antibacterial activity against four strains of bacteria. The HPLC results indicated that the mycelial extracts of AP-4 and AP-12 contained diterpene lactones. The two endophytic fungi were recognized as Colletotrichum sp. The study successfully obtained diterpene lactones from the endophytic fungus of Andrographis paniculata and confirmed the feasibility of using endophytic fungal strains to produce active substances consistent with the host. It was also useful for exploring endophytic fungi and medicinal plants. The relationship provides theoretical guidance.

In vitro and in silico investigation of the antifungal activity of endophytic fungi against phytopathogenic fungi of tomato

Plants are threatened by several diseases caused by phytopathogenic fungi. Melanin is an important pathogenicity factor in some fungal plant diseases. The enzyme 6,3,8-trihydroxynaphthalene reductase (3HNR) is implicated in the catalysis of the melanin biosynthesis in fungi. The chemical fungicide Phthalide acts by inhibiting this enzyme. But despite its efficacy, Phthalide can be detrimental to environmental health, hence the need to look for natural inhibitors to combat phytopathogenic fungi. This study aimed to screen the antifungal activity of some endophytic strains against phytopathogenic fungi of tomato. A total of 7 endophytic fungi were isolated and pre-identified from different parts of celery, parsley, mint, and coriander. On the other hand, five phytopathogenic fungal strains were isolated and pre-identified from tomatoes. The agar cylinder method showed that the endophytic fungi strains Fusarium and Trichoderma have significant inhibitory activity against four phytopathogenic fungi identified as Alternaria and Penicillium. Molecular docking was also used to study the inhibitory effect of some bioactive fungal compounds against the 3HNR enzyme. Drug-likeness and ADMET analyses were conducted on the selected chemicals to test their reliability and pharmaceutical efficacy. Phenylethyl alcohol interacts intensely with the binding site of the 3HNR receptor giving binding energy of -5.3 Kcal/mol, which is close to the co-crystallized ligand Phthalide. In addition, ADMET and pharmacokinetic analysis revealed that Phenylethyl alcohol verify the majority of the filters and pharmacokinetic properties necessary to select an effective antifungal molecule, including Lipinski’s and Veber’s rules.

Discovery of ent-kaurane diterpenoids, characteristic metabolites of Isodon species, from an endophytic fungal strain Geopyxis sp. XY93 inhabiting Isodon parvifolia

Isogeopyxins A–C (1–3), three new diterpenoids with ent-kaurane, ent-pimarane, and ent-abietane scaffolds, respectively, along with six known ent-kauranoids, were isolated from the fermentation culture of Geopyxis sp. XY93 inhabiting the leaves of Isodon parvifolia. Their structures were elucidated by interpretation of spectroscopic data, and single crystal X-ray diffraction. It marks the first time that ent-kauranoids, characteristic metabolites of Isodon species, have been isolated from an associated endophytic fungus.

Mechanisms in Growth-Promoting of Cucumber by the Endophytic Fungus Chaetomium globosum Strain ND35.

Endophytic fungi are effective in plant growth and development by secreting various kinds of plant hormones and nutrients. However, the cellular and molecular interactions between the endophytic fungi and plant growth-promoting have remained less explored. The present study was designed to explore the effects of the infection and colonization events of Chaetomium globosum strain ND35 on cucumber growth and the expression pattern of some metabolically important genes in development of the cucumber radicle. The results demonstrated that strain ND35 can infect and colonize the outer layers (cortical cells) of cucumber root and form a symbiotic structure with the host cell, similar to a periarbuscular membrane and establish chemical communication with the plant. Through transcriptome analysis, we found the differentially expressed genes (DEGs) caused by strain ND35 were mainly enriched in phenylpropanoid biosynthesis, plant hormone signal transduction, plant-pathogen interaction and photosynthesis. Correspondingly, the contents of reactive oxygen species (ROS), hydrogen peroxide (H2O2), indole-3-acetic acid (IAA), gibberellin (GA), zeatin (ZT), salicylic acid (SA), jasmonic acid (JA) and the activity of phenylalanine ammonia lyase (PAL), 4-coumarate-CoA ligase (4CL), cinnamyl alcohol dehydrogenase (CAD), and peroxidase (POD) in ND35-colonized seedlings were generally higher than those of non-inoculated seedlings. Overall, the infection and colonization events of C. globosum strain ND35 increased cucumber growth through complex regulation of plant hormones biosynthesis and metabolism. Furthermore, although the endophytic fungus strain ND35 produced IAA, GA, ZT, and ergosterol in the fermentation broth, and there are enabled to promote growth of cucumber, it is uncertain whether there are ND35-derived microbial hormones in plants. This study of the interaction between cucumber and strain ND35 contributes to a better understanding of the plant-endophytic fungi interactions, and may help to develop new strategies for crop production.

Screening of endophytic fungi as potential antagonistic agents of Pyricularia oryzae and evaluation of their ability in producing hydrolytic enzymes

Abstract. Putri ND, Sulistyowati L, Aini LQ, Muhibuddin A, Trianti I. 2022. Screening of endophytic fungi as potential antagonistic agents of Pyricularia oryzae and evaluation of their ability in producing hydrolytic enzymes. Biodiversitas 23: 1048-1057. One of the most important phytopathogenic fungi is Pyricularia oryzae, as it is the causative agent of rice blast diseases, which is the most destructive and detrimental disease in rice. Biological control using endophytic fungi can be an alternative to control blast diseases. Endophytic fungi are fungi that colonize internal plant tissues without apparently damaging the host. The aim of this study was to isolate endophytic fungi that produce hydrolytic enzymes and to investigate their ability to suppress blast disease. In this study, fifty strains of endophytic fungi were successfully obtained from rice leaves. Three fungi with the highest inhibition against P. oryzae were identified as Trichoderma asperellum, Curvularia chiangmaiensis, and Fusarium solani by analyzing fungal ITS sequence. They can produce chitinase ranging from 1.43 to 151 ?g/mL and cellulase ranging from 1.83 to 4.09 ?g/mL, which were hydrolytic enzymes that account for the lysis of phytopathogens. This enzymatic activity can cause damage and degradation of cell walls. SEM results revealed that these endophytic fungi probably excreted wall lytic enzymes or antifungal substances, inflicting wrinkles and disintegrating P. oryzae mycelium.

Combination of Pseudo-LC-NMR and HRMS/MS-Based Molecular Networking for the Rapid Identification of Antimicrobial Metabolites From Fusarium petroliphilum.

An endophytic fungal strain isolated from a seagrass endemic to the Mediterranean Sea (Posidonia oceanica) was studied in order to identify its antimicrobial constituents and further characterize the composition of its metabolome. It was identified as Fusarium petroliphilum by in-depth phylogenetic analyses. The ethyl acetate extract of that strain exhibited antimicrobial activities and an ability to inhibit quorum sensing of Staphylococcus aureus. To perform this study with a few tens of mg of extract, an innovative one-step generic strategy was devised. On one side, the extract was analyzed by UHPLC-HRMS/MS molecular networking for dereplication. On the other side, semi-preparative HPLC using a similar gradient profile was used for a single-step high-resolution fractionation. All fractions were systematically profiled by 1H-NMR. The data were assembled into a 2D contour map, which we call “pseudo-LC-NMR,” and combined with those of UHPLC-HRMS/MS. This further highlighted the connection within structurally related compounds, facilitated data interpretation, and provided an unbiased quantitative profiling of the main extract constituents. This innovative strategy led to an unambiguous characterization of all major specialized metabolites of that extract and to the localization of its bioactive compounds. Altogether, this approach identified 22 compounds, 13 of them being new natural products and six being inhibitors of the quorum sensing mechanism of S. aureus and Pseudomonas aeruginosa. Minor analogues were also identified by annotation propagation through the corresponding HRMS/MS molecular network, which enabled a consistent annotation of 27 additional metabolites. This approach was designed to be generic and applicable to natural extracts of the same polarity range.

Oxic and Anoxic Organic Polymer Degradation Potential of Endophytic Fungi From the Marine Macroalga, Ecklonia radiata.

Cellulose and chitin are the most abundant polymeric, organic carbon source globally. Thus, microbes degrading these polymers significantly influence global carbon cycling and greenhouse gas production. Fungi are recognized as important for cellulose decomposition in terrestrial environments, but are far less studied in marine environments, where bacterial organic matter degradation pathways tend to receive more attention. In this study, we investigated the potential of fungi to degrade kelp detritus, which is a major source of cellulose in marine systems. Given that kelp detritus can be transported considerable distances in the marine environment, we were specifically interested in the capability of endophytic fungi, which are transported with detritus, to ultimately contribute to kelp detritus degradation. We isolated 10 species and two strains of endophytic fungi from the kelp Ecklonia radiata. We then used a dye decolorization assay to assess their ability to degrade organic polymers (lignin, cellulose, and hemicellulose) under both oxic and anoxic conditions and compared their degradation ability with common terrestrial fungi. Under oxic conditions, there was evidence that Ascomycota isolates produced cellulose-degrading extracellular enzymes (associated with manganese peroxidase and sulfur-containing lignin peroxidase), while Mucoromycota isolates appeared to produce both lignin and cellulose-degrading extracellular enzymes, and all Basidiomycota isolates produced lignin-degrading enzymes (associated with laccase and lignin peroxidase). Under anoxic conditions, only three kelp endophytes degraded cellulose. We concluded that kelp fungal endophytes can contribute to cellulose degradation in both oxic and anoxic environments. Thus, endophytic kelp fungi may play a significant role in marine carbon cycling via polymeric organic matter degradation.

Antimicrobial, Antioxidant, Cytotoxic Activities and Phytochemical Analysis of Fungal Endophytes Isolated from Ocimum Basilicum.

Fungal endophytes are living inside plants without any harmful effects; the prospecting about them is increased day by day because they can produce bioactive compounds which can be used in different applications. Herein, thecurrent study was aimed to isolate the endophytic fungi from the Ocimum basilicum plant as safe microorganisms and evaluate their biological activities. The results illustrated that three endophytic fungal strains were isolated and identified morphologically and genetically as Aspergillus nidulans, Aspergillus fumigatus, and Aspergillus flavus and deposited in gene bank under accession numbers MZ045561, MZ045562, and MZ045563 respectively. Moreover, cell-free filtrates of endophytic fungal strains were extracted using ethyl acetate, where these crude extracts exhibited promising antimicrobial activity against Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Klebsiella pneumonia, and Candida albicans at a concentration of 1000µg/mL. Furthermore, these endophytic strains exhibited a potential antioxidant activity where IC50 of the crude extract of A. nidulans, A. fumigatus, and A. flavus were (166.3, 68.4, and 347.1 µg/mL) and (151.2, 77.9, and 246.3µg/mL) using DPPH and ABTS methods, respectively. Furthermore, the ethyl acetate crude extracts of these endophytic fungi did not exhibit any cytotoxic effect against Vero and Wi 38 normal cells. GC-MS analysis of the crude extract of A. nidulans, A. fumigatus, and A. flavus indicated the presence of 22, 22, and 20 active compounds, respectively. The major compounds in the fungal extracts are belonging to fatty acids, fatty acid esters, tetrahydrofurans, and sterols. In conclusion, the isolated endophytic A. nidulans, A. fumigatus, and A. flavus from Ocimum basilicum are promising sources for bioactive compounds.