Bioprospecting endophytic fungi for bioactive metabolites and use of irradiation to improve their bioactivities

Bioprospecting endophytic fungi of forest plants for their monoamine oxidase A and cholinesterases inhibitors, and peroxisome proliferator-activated receptor gamma agonists

AIMS

The urgent search for new natural bioactive compounds is crucial to address growing clinical demands. With this perspective, this paper focuses on isolating and bioprospecting fungal endophytes from some plant species in a local forest in Wrocław, Poland.

METHODS AND RESULTS

Forty-three fungal endophytes were isolated and their extracts were tested for inhibitory potential against monoamine oxidase A (MAO-A), acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and for peroxisome proliferator-activated receptor gamma (PPAR-γ) agonists. Six promising strains after screening were identified to possess all these activities. These strains and their respective plant hosts were Sphaeropsis sapinea BUK-L2 (Fagus sylvatica), Coniochaeta velutina SW-B (Picea abies), Epicoccum nigrum COR-B (Corylus avellana), Paraphaeosphaeria verruculosa JAR-B (Sorbus aucuparia), Umbelopsis isabellina COR-L1 (Corylus avellana), and Epicoccum mezzettii QR-B (Quercus robur). Moreover, gamma irradiation at several doses (Gy) was separately applied to the fungal cultures to study their enhancement effects on the recorded activities. Finally, compounds of active bands from preparative thin-layer chromatography of the two promising strains (Coniochaeta velutina SW-B and Epicoccum nigrum COR-B), were identified by GC-MS (Gas chromatography-mass spectrometry).

CONCLUSIONS

The present study is the first report on bioprospecting endophytic fungi of forest plants for the aforementioned activities.

Bioprospecting Endophytic Fungi of Forest Plants for Bioactive Metabolites with Antibacterial, Antifungal, and Antioxidant Potentials

The growing emergence of multi-drug resistant microbial strains has kept the scientific world searching for novel bioactive compounds with specific chemical characteristics. Accordingly, researchers have started exploring the understudied metabolites from endophytes as a new source of bioactive compounds. In this context, the current study was designed to evaluate the bioactive properties of endophytic fungi from the Mokrzański forest in Wrocław, Poland that have not yet been fully researched. Forty-three endophytic fungi were isolated from twelve distinct plants. Following their cultivation, fungal extracts were separately prepared from biomass and cell-free filtrates, and their antibacterial, antifungal (against human and plant pathogens), and antioxidant properties were examined. Five promising fungi after screening were identified to possess all of these activities. These strains and their respective plant hosts were Trichoderma harzianum BUK-T (Fagus sylvatica), Aspergillus ochraceus ROB-L1 (Robinia pseudoacacia), Chaetomium cochliodes KLON-L1, Fusarium tricinctum KLON-L2 (Acer platanoides), and Penicillium chrysogenum SOS-B2 (Pinus sylvestris). Moreover, gamma irradiation at several doses (Gy) was separately applied to the fungal cultures to study their effects on the recorded activities. Finally, compounds after preparative thin-layer chromatography fractionation of the five fungal strains were identified by GC-MS. These findings suggest that the isolated endophytic fungi could serve as novel sources of bioactive metabolites with antibacterial, antifungal, and antioxidant properties, potentially paving the way for future research and the development of new bioactive compounds.

Evaluation of resistance patterns and bioremoval efficiency of hydrocarbons and heavy metals by the mycobiome of petroleum refining wastewater in Jazan with assessment of molecular typing and cytotoxicity of Scedosporium apiospermum JAZ-20

Jazan Industrial Economic City (JIEC) is located on the Red Sea coast in the province of Jazan, southwest of Saudi Arabia anchors diverse heavy and secondary industries in the energy, water desalination, petroleum, aluminum, copper, refineries, pharmaceuticals and food manufacturing fields. These various industries generate a large quantity of industrial wastewaters containing various toxicants. The present work represents ecologically beneficial alternatives for the advancement of environmental biotechnology, which could help mitigate the adverse impacts of environmental pollution resulting from petroleum refining effluents. The mycobiome (32 fungal strains) isolated from the industrial wastewater of the refinery sector in Jazan were belonged to five fungal genera including Fusarium, Verticillium, Purpureocillium, Clavispora and Scedosporium with a distribution percentage of 31.25, 21.88, 15.63, 12.50 and 18.75 %, respectively. These isolates showed multimetals tolerance and bioremoval efficiency against a large number of heavy metals (Fe2+, Ni2+, Cr6+, Zn2+, As3+, Cu2+, Cd2+, Pb2+, Ag+ and Hg2+) along with potent bioremediation activity toward crude oil and the polycyclic aromatic hydrocarbons. Interestingly, the mycobiome resistance patterns obtained against different classes of fungal antibiotics including azole (fluconazole, itraconazole, voriconazole, posaconazole, isavuconazole and ketoconazole), echinocandin (anidulafungin, caspofungin and micafungin) and polyene (amphotericin B) drugs proved the prevalence of antibiotic resistance among the mycobiome of refinery industry in Saudi Arabia is relatively low. The fungal isolate under isolation code JAZ-20 showed the highest bioremoval efficiency against heavy metals (90.8-100.0 %), crude oil (89.50 %), naphthalene (96.7 %), phenanthrene (92.52 %), fluoranthene (100.0 %), anthracene (90.34 %), pyrene (85.60 %) and chrysene (83.4 %). It showed the highest bioremoval capacity ranging from 85.72 % to 100.0 % against numerous pollutants found in a wide array of industrial effluents, including diclofenac, ibuprofen, carbamazepine, acetaminophen, sulfamethoxazole, bisphenol, bleomycin, vincristine, dicofol, methyl parathion, atrazine, diuron, dieldrin, chlorpyrifos, profenofos and phenanthrene. The isolate JAZ-20 was chosen for molecular typing, cytotoxicity assessment, analysis of volatile compounds and optimization investigations. Based on phenotypic, biochemical and phylogenetic analysis, strain JAZ-20 identified as Scedosporium apiospermum JAZ-20. This strain is newly discovered in industrial effluents in Saudi Arabia. Fungal strain JAZ-20 consistently produced various types of saturated and unsaturated fatty acids. the main fatty acids were C14:0 (1.95 %), iso-C14:0 (2.98 %), anteiso-C14:0 (2.13 %), iso-C15:0 (9.16 %), anteiso-C15:0 (11.75 %), C15:0 (7.42 %), C15:1 (2.37 %), anteiso-C16:0 (3.4 %), C16:0 (10.3 %), iso-C16:0 (9.5 %), C17:1 (1.36 %), anteiso-C17:1 (8.64 %), iso-C18:0 (11.0 %), C18:0 (3.63 %), anteiso-C19:0 (3.78 %), anteiso-C20:0 (2.0 %), iso-C21:0 (2.44 %), C23:0 (1.15 %), and C24:0 (2.17 %). These fatty acids serve as natural and eco-friendly antifungal agents, promoting fungal resistance and inhibiting the production of mycotoxins in the environment. Despite being an environmental isolate, its cytotoxicity was assessed against both normal and cancerous human cell lines. The IC50 values of JAZ-20 extract were 8.92, 10.41, 20.0, 16.5, and 40.0 μg/mL against WI38, MRC5, MCF10A, HEK293 and HDFs normal cells and 43.26, 33.75, and 40.0 μg/mL against liver (HepG2), breast (A549) and cervix (HeLa) cancers, respectively. Based on gas chromatography-mass spectrometry (GC-MS), analysis the extract of S. apiospermum JAZ-20 showed 47 known volatile compounds (VOCs) for varied and significant biological activities. Enhancing the bioremoval efficiency of heavy metals from actual refining wastewater involves optimizing process parameters. The parameters optimized were the contact time, the fungal biomass dosage, pH, temperature and agitation rate.

Bioprospecting endophytic fungi for bioactive metabolites with seed germination promoting potentials

There is an urgent need for new bioactive molecules with unique mechanisms of action and chemistry to address the issue of incorrect use of chemical fertilizers and pesticides, which hurts both the environment and the health of humans. In light of this, research was done for this work to isolate, identify, and evaluate the germination-promoting potential of various plant species' fungal endophytes. Zea mays L. (maize) seed germination was examined using spore suspension of 75 different endophytic strains that were identified. Three promising strains were identified through screening to possess the ability mentioned above. These strains Alternaria alternate, Aspergilus flavus, and Aspergillus terreus were isolated from the stem of Tecoma stans, Delonix regia, and Ricinus communis, respectively. The ability of the three endophytic fungal strains to produce siderophore and indole acetic acid (IAA) was also examined. Compared to both Aspergillus flavus as well as Aspergillus terreus, Alternaria alternata recorded the greatest rates of IAA, according to the data that was gathered. On CAS agar versus blue media, all three strains failed to produce siderophores. Moreover, the antioxidant and antifungal potentials of extracts from these fungi were tested against different plant pathogens. The obtained results indicated the antioxidant and antifungal activities of the three fungal strains. GC-Mass studies were carried out to determine the principal components in extracts of all three strains of fungi. The three strains' fungus extracts included both well-known and previously unidentified bioactive compounds. These results may aid in the development of novel plant growth promoters by suggesting three different fungal strains as sources of compounds that may improve seed germination. According to the study that has been given, as unexplored sources of bioactive compounds, fungal endophytes have great potential.

Xenomyrothecium tongaense PTS8: a rare endophyte of Polianthes tuberosa with salient antagonism against multidrug-resistant pathogens

Introduction

Endophytes refer to microorganisms residing within the endosphere of plants, particularly perennials, without inflicting noticeable injury or inducing obvious morphological variations to their host plant or host organism. Endophytic fungi, although often overlooked microorganisms, have garnered interest due to their significant biological diversity and ability to produce novel pharmacological substances.

Methods

In this study, fourteen endophytic fungi retrieved were from the stem of the perennial plant Polianthes tuberosa of the Asparagaceae family. These fungal crude metabolites were tested for antagonistic susceptibility to Multi-Drug Resistant (MDR) pathogens using agar well diffusion, Minimum Inhibitory Concentration (MIC), and Minimum Bactericidal Concentration (MBC) assays. The chequerboard test was used to assess the synergistic impact of active extract.

Results and discussion

In early antibacterial screening using the Agar plug diffusion test, three of fourteen endophytes demonstrated antagonism against Methicillin-resistant Staphylococcus aureus (MRSA) and Vancomycin-resistant Enterococcus (VRE). Three isolates were grown in liquid medium and their secondary metabolites were recovered using various organic solvents. Eight extracts from three endophytic fungi displayed antagonism against one or more human pathogens with diameters ranging from 11 to 24 mm. The highest antagonistic effect was obtained in ethyl acetate extract for PTS8 isolate against two MRSA (ATCC 43300, 700699) with 20 ± 0.27 and 22 ± 0.47 mm zones of inhibition, respectively, among different solvent extracts. The extract had MICs of 3.12 ± 0.05 and 1.56 ± 0.05 μg/mL, and MBCs of 50 ± 0.01 and 12.5 ± 0.04 μg/mL, respectively. Antagonism against VRE was 18 ± 0.23 mm Zone of Inhibition (ZOI) with MIC and MBC of 6.25 ± 0.25 and 25 ± 0.01 μg/mL. When ethyl acetate extract was coupled with antibiotics, the chequerboard assay demonstrated a synergistic impact against MDR bacteria. In an antioxidant test, it had an inhibitory impact of 87 ± 0.5% and 88.5 ± 0.5% in 2,2-Diphenyl-1-Picrylhydrazyl and reducing power assay, respectively, at 150 μg/mL concentration. PTS8 was identified as a Xenomyrothecium tongaense strain by 18S rRNA internal transcribed spacer (ITS) sequencing. To our insight, it is the foremost study to demonstrate the presence of an X. tongaense endophyte in the stem of P. tuberosa and the first report to study the antibacterial efficacy of X. tongaense which might serve as a powerful antibacterial source against antibiotic-resistant human infections.

Improvement in the Phytochemical Content and Biological Properties of Stevia rebaudiana (Bertoni) Bertoni Plant Using Endophytic Fungi Fusarium fujikuroi

This study aimed to increase the therapeutic potential of medicinal plants through inoculation with endophytic fungi. As endophytes influence medicinal plants' biological properties, twenty fungal strains were isolated from the medicinal plant Ocimum tenuiflorum. Among all fungal isolates, the R2 strain showed the highest antagonistic activity towards plant pathogenic fungi Rosellinia necatrix and Fusarium oxysporum. The partial ITS region of the R2 strain was deposited in the GenBank nucleotide sequence databases under accession number ON652311 as Fusarium fujikuroi isolate R2 OS. To ascertain the impact of an endophytic fungus on the biological functions of medicinal plants, Stevia rebaudiana seeds were inoculated with Fusarium fujikuroi (ON652311). In the DPPH assay, the IC₅₀ value of the inoculated Stevia plant extracts (methanol, chloroform, and positive control) was 72.082 µg/mL, 85.78 µg/mL, and 18.86 µg/mL, respectively. In the FRAP assay, the IC₅₀ value of the inoculated Stevia extracts (methanol, chloroform extract, and positive control) was 97.064 µM Fe²⁺ equivalents, 117.662 µM Fe²⁺ equivalents, and 53.384 µM Fe²⁺ equivalents, respectively. In the extracts of the plant inoculated with endophytic fungus, rutin and syringic acid (polyphenols) concentrations were 20.8793 mg/L and 5.4389 mg/L, respectively, which were higher than in the control plant extracts. This approach can be further utilized for other medicinal plants to increase their phytochemical content and hence medicinal potential in a sustainable way.

Unlocking the biosynthetic potential of Penicillium roqueforti for hyperproduction of the immunosuppressant mycophenolic acid: Gamma radiation mutagenesis and response surface optimization of fermentation medium

Based on the broad clinical utility of the immunosuppressant mycophenolic acid (MPA), this article aims to intensify the biosynthetic potential of Penicillium roqueforti for more effective hyperproduction of the drug. Several mutants were generated from irradiation mutagenesis and screened. Two strains (GM1013 and GM1093) presented an elevated MPA productivity with significant yield constancy over 10 subsequent generations. By investigating the effect of some phosphorous sources and mineral salts on MPA production by the two mutants, KH₂ PO₄ and FeSO₄ ·7H₂ O were most preferred by the two mutants for higher MPA production rates. Statistics-dependent experimental designs were also employed for optimizing medium components for maximum MPA production. Medium components were primarily screened using the Plackett-Burman model to demonstrate the most important components that most significantly affect MPA production. The concentrations of these significant components were then optimized through a central composite rotatable model. In conclusion, gamma-radiation mutation and response surface optimization resulted in a promising MPA productivity by P. roqueforti GM1013. To our knowledge, the MPA-yield achieved in this study (2933.32 mg L^-1 ) is the highest reported by academic laboratories from P. roqueforti cultures, which could be of economic value for a prospective large industrialized application.

Improving carboxymethyl cellulose edible coating using ZnO nanoparticles from irradiated Alternaria tenuissima

In this paper, gamma-irradiation was successfully used to intensify the yield of Zinc oxide nanoparticles (ZnONPs) produced by the fungus Alternaria tenuissima as a sustainable and green process. The obtained data showed that 500 Gy of gamma-irradiation increased ZnONPs' yield to approximately four-fold. The synthesized ZnONPs were then exploited to develop active Carboxymethyl Cellulose films by casting method at two different concentration of ZnONPs 0.5% and 1.0%. The physicochemical, mechanical, antioxidant, and antimicrobial properties of the prepared films were evaluated. The incorporation of ZnONPs in the Carboxymethyl Cellulose films had significantly decreased solubility (from 78.31% to 66.04% and 59.72%), water vapor permeability (from 0.475 g m-2 to 0.093 g m-2 and 0.026 g m-2), and oxygen transfer rate (from 24.7 × 10-2 to 2.3 × 10-2 and 1.8 × 10-2) of the respective prepared films. Meanwhile, tensile strength (from 183.2 MPa to 203.34 MPa and 235.94 MPa), elongation (from 13.0% to 62.5% and 83.7%), and Yang's modulus (from 325.344 to 1410.0 and 1814.96 MPa) of these films were increased. Moreover, the antioxidant and antimicrobial activities against several human and plant pathogens the prepared of Carboxymethyl Cellulose-ZnONPs films were significantly increased. In conclusion, the prepared Carboxymethyl Cellulose-ZnONPs films showed enhanced activities in comparison with Carboxymethyl Cellulose film without NPs. With these advantages, the fabricated Carboxymethyl Cellulose-ZnONPs films in this study could be effectively utilized as protective edible coating films of food products.

A Review on Medicinal Plants Having Anticancer Properties of Northeast India and Associated Endophytic Microbes and their Future in Medicinal Science

Human beings are affected by different diseases and suffer to different extents. Cancer is one of the major human disease and millions of people suffered from cancer and end their lives every year. Peoples are dependent on herbal medicines since prehistoric time especially from developing countries. It is very common to have different side effects of modern synthetic medicines; hence now-a-days importance of herbal medicines due to no or least side effects increases all parts of the world. But the major problems of using herbal medicines are that plants can produce very limited amount of medicinally important bioactive metabolites and they have very long growth periods. Therefore endophytes are the excellent alternative of plant derived metabolites. Endophytic microbes can synthesize exactly same type of metabolites as the plant produces. North East India is a treasure of plant resources; various types of medicinal plants are present in this region. Different types of indigenous tribes are inhabited in this region who used different plants in traditional system for treating various disease. But with increasing demand it is sometimes not sufficient to manage the demand of medicines, therefore for massive production endophytic study is crucial. In spite of having huge plant resources very limited endophytic studies are observed in this region. In this review, we studied different plants with their endophytes of NE India showing anticancer properties.

A new endophyte Monascus ruber SRZ112 as an efficient production platform of natural pigments using agro-industrial wastes

A number of biopigment applications in various industrial sectors are gaining importance due to the growing consumer interest in their natural origin. Thus, this work was conducted to valorize endophytic fungi as an efficient production platform for natural pigments. A promising strain isolated from leaves of Origanum majorana was identified as Monascus ruber SRZ112 produced several types of pigments. The nature of the pigments, mainly rubropunctamine, monascin, ankaflavin, rubropunctatin, and monascorubrin in the fungal extract was studied by LC/ESI-MS/MS analyses. As a first step towards developing an efficient production of red pigments, the suitability of seven types of agro-industrial waste was evaluated. The highest yield of red pigments was obtained using potato peel moistened with mineral salt broth as a culture medium. To increase yield of red pigments, favourable culture conditions including incubation temperature, incubation period, pH of moistening agent, inoculum concentration, substrate weight and moisture level were evaluated. Additionally, yield of red pigments was intensified after the exposure of M. ruber SRZ112 spores to 1.00 KGy gamma rays. The final yield was improved by a 22.12-fold increase from 23.55 to 3351.87 AU g-1. The anticancer and antioxidant properties of the pigment's extract from the fungal culture were also studied. The obtained data indicated activity of the extract against human breast cancer cell lines with no significant cytotoxicity against normal cell lines. The extract also showed a free radical scavenging potential. This is the first report, to our knowledge, on the isolation of the endophytic M. ruber SRZ112 strain with the successful production of natural pigments under solid-state fermentation using potato peel as a substrate.

Harnessing endophytic fungi for biosynthesis of selenium nanoparticles and exploring their bioactivities

In the light of the fast growing several applications of selenium nanoparticles (SeNPs) in different industrial and agricultural sectors, this paper was conducted to explore the suitability of endophytic fungi as nano-factories for SeNPs. Thus, 75 fungal isolates were recovered from plant tissues and tested for their efficacy to biosynthesize SeNPs. Four promising strains were found able to synthesis SeNPs with different characteristics and identified. These strains were Aspergillus quadrilineatus isolated from the twigs of Ricinus communis, Aspergillus ochraceus isolated from the leaves of Ricinus communis, Aspergillus terreus isolated from the twigs of Azadirachta indica, and Fusarium equiseti isolated from the twigs of Hibiscus rose-sinensis. The synthesized SeNPs were characterized by several techniques viz., UV–Vis, X-ray diffraction, Dynamic light scattering analyses, High resolution transmission electron microscopy, and Fourier transform infrared spectroscopy, to study their crystalline structure, particle sized distribution, and morphology. Furthermore, the in vitro antimicrobial and antioxidant activities were evaluated. SeNPs synthesized by the four strains showed potent antifungal and antibacterial potentials against different human and phyto- pathogens. Moreover, SeNPs synthesized by the respective strains showed promising antioxidant power with IC₅₀ values of 198.32, 151.23, 100.31, and 91.52 µg mL^− 1. To the best of our knowledge, this is the first study on the use of endophytic fungi for SeNPs’ biosynthesis. The presented research recommends the use of endophytic fungi as facile one-pot production bio-factories of SeNPs with promising characteristics.

Discovery of four different promising endophytic fungi for a facile-synthesis of SeNPs.

SeNPs were successfully mycosynthesized and characterized.

SeNPs exhibited promising antifungal, antibacterial, and antioxidant activities.