High-throughput sequencing-based analysis of the composition and diversity of the endophyte community in roots of Stellera chamaejasme.

Stellera chamaejasme (S. chamaejasme) is an important medicinal plant with heat-clearing, detoxifying, swelling and anti-inflammatory effects. At the same time, it is also one of the iconic plants of natural grassland degradation in northwest China, playing a key role in the invasion process. Plant endophytes live in healthy plant tissues and can synthesize substances needed for plant growth, induce disease resistance in host plants, and enhance plant resistance to environmental stress. Therefore, studying the root endophytes of S. chamaejasme is of great significance for mining beneficial microbial resources and biological prevention and control of S. chamaejasme. This study used Illumina MiSeq high-throughput sequencing technology to analyze the composition and diversity of endophytes in the roots of S. chamaejasme in different alpine grasslands (BGC, NMC and XGYZ) in Tibet. Research results show that the main phylum of endophytic fungi in the roots of S. chamaejasme in different regions is Ascomycota, and the main phyla of endophytic bacteria are Actinobacteria, Proteobacteria and Firmicutes (Bacteroidota). Overall, the endophyte diversity of the NMC samples was significantly higher than that of the other two sample sites. Principal coordinate analysis (PCoA) and permutational multivariate analysis of variance (PERMANOVA) results showed significant differences in the composition of endophytic bacterial and fungal communities among BGC, NMC and XGYZ samples. Co-occurrence network analysis of endophytes showed that there were positive correlations between fungi and some negative correlations between bacteria, and the co-occurrence network of bacteria was more complex than that of fungi. In short, this study provides a vital reference for further exploring and utilizing the endophyte resources of S. chamaejasme and an in-depth understanding of the ecological functions of S. chamaejasme endophytes.

The other side of the coin: systemic effects of Serendipita indica root colonization on development of sedentary plant-parasitic nematodes in Arabidopsis thaliana.

MAIN CONCLUSION: Upon systemic S. indica colonization in split-root system cyst and root-knot nematodes benefit from endophyte-triggered carbon allocation and altered defense responses what significantly facilitates their development in A. thaliana. Serendipita indica is an endophytic fungus that establishes mutualistic relationships with different plants including Arabidopsis thaliana. It enhances host's growth and resistance to different abiotic and biotic stresses such as infestation by the cyst nematode Heterodera schachtii (CN). In this work, we show that S. indica also triggers similar direct reduction in development of the root-knot nematode Meloidogyne javanica (RKN) in A. thaliana. Further, to mimick the natural situation occurring frequently in soil where roots are unequally colonized by endophytes we used an in vitro split-root system with one half of A. thaliana root inoculated with S. indica and the other half infected with CN or RKN, respectively. Interestingly, in contrast to direct effects, systemic effects led to an increase in number of both nematodes. To elucidate this phenomenon, we focused on sugar metabolism and defense responses in systemic non-colonized roots of plants colonized by S. indica. We analyzed the expression of several SUSs and INVs as well as defense-related genes and measured sugar pools. The results show a significant downregulation of PDF1.2 as well as slightly increased sucrose levels in the non-colonized half of the root in three-chamber dish. Thus, we speculate that, in contrast to direct effects, both nematode species benefit from endophyte-triggered carbon allocation and altered defense responses in the systemic part of the root, which promotes their development. With this work, we highlight the complexity of this multilayered tripartite relationship and deliver new insights into sugar metabolism and plant defense responses during S. indica-nematode-plant interaction.

Evaluation of Antifungal Activity of Endophytic Bacillus spp. and Identification of Secondary Metabolites Produced Against the Phytopathogenic Fungi.

Endophytic bacteria serve as a rich source of diverse antimicrobial compounds. Recently, there has been a growing interest in utilizing endophytic Bacillus spp. as biological agents against phytogenic fungi, owing to their potential to produce a wide range of antimicrobial substances. The objective of this research was to investigate the protective abilities of 15 endophytic Bacillus spp. isolated from previous study from wheat plant, against the phytopathogenic fungi, Fusarium graminearum and Macrophomina phaseolina. A dual culture plate assay was conducted as a preliminary analysis, revealing that 7 out of 15 endophytic Bacillus spp. demonstrated inhibition against one or both of the phytopathogenic fungi used in this study. All seven endophytes were further assessed for the presence of diffusible antifungal metabolites. The cultures were grown in potato dextrose broth for 120 h, and the cell-free supernatant was extracted and analyzed using the cup plate method. The methanolic extract yielded similar results to the dual culture plate analysis, except for WL2-15. Additionally, deformities in the mycelial structure were examined under the light microscope upon exposure to methanolic extract. Furthermore, the analysis and identification of metabolites were carried out via gas chromatography-mass spectrometry of methanolic extract from selected seven endophytic Bacillus spp. The chromatogram revealed the presence of some major peaks such as tridecanoic acid, methyl ester, hydroperoxide, 1-methylbutyl, 9-octadecenamide, (z)-, hexane-1,3,4-triol, 3,5-dimethyl- tetradecanoic acid. To the best of our knowledge, this is the first report of these biocontrol agents in endophytic Bacillus spp. Interestingly, volatile organic compound production was also seen in all the isolates against the phytopathogenic fungi.

Halophytic Bacterial Endophyte Microbiome from Coastal Desert-Adapted Wild Poaceae Alleviates Salinity Stress in the Common Wheat Triticum aestivum L.

Abiotic stresses threaten the strategic crops of Poaceae (Gramineae) worldwide. Habitat-adapted microbiome of wild plants has the potential to alleviate abiotic stresses in alternate hosts. Persian Gulf's coastal deserts are colonized by halophyte plants hosting habitat-adapted halophytic microbiota. Here, endophytic bacteria from wild Poaceae in coastal deserts of the north Persian Gulf at Hormozgan province, Iran, were isolated and screened for mitigating salinity stress in wheat. Accordingly, seven dominant species of wild Poaceae in the region, i.e., Aeloropus lagopoides, Aeloropus litiralis, Chrysopogon aucheri, Cymbopogon olivieri, Desmostachya sp., Halopayrum mucronatum, and Sporbuls arabicus, were explored. In total, 367 endophytic bacteria were isolated, 90 of which tolerated 2.5-M NaCl. Of these, 38 strains were selected based on their bioactivity and applied for in vitro wheat-interaction assays under 250-mM NaCl stress. Five superior strains promoted seed germination and growth indices in rain-fed winter wheat cv. Sardari, i.e., Bacillus subtilis B14, B19, & B27, Bacillus sp. B21, and Bacillus licheniformis Ba38. In planta assays in saline soil (2.7 dS m-1) using the superior strains indicated that Bacillus sp. B21 and Bacillus licheniformis Ba38 increased germination and root and shoot lengths and their dry and fresh weights in wheat seedlings. Moreover, phenolics and flavonoids contents of wheat seedlings were influenced by endophyte application. Thus, the coastal desert-adapted microbiome of wild Poaceae could alleviate abiotic stress and promote growth in cultivated species of Poaceae, such as wheat.

Growth-promoting effects of Aspergillus Elegans and the dark septate endophyte (DSE) Periconia macrospinosa on cucumber.

Cucurbits are subject to a variety of stresses that limit their sustainable production, despite their important role in ensuring food security and nutrition. Plant stress tolerance can be enhanced through fungal endophytes. In this study, two endophytes isolated from wild plant roots, were tested to determine their effect on the growth promotion of cucumber (Cucumis sativus L.) plants. The phylogenetic analysis revealed that the designated isolates were Aspergillus elegans and Periconia macrospinosa. The results of the Plant Growth Promoting Fungal (PGPF) tests showed that both Aspergillus elegans and Periconia macrospinosa have a zinc solubilizing capacity, especially A. elegans, with a solubilization index higher than 80%. Also, both have a high salt tolerance (10-15% NaCl for P. macrospinosa and A. elegans, respectively), cellulolytic activity, and inhibition indices of 40-64.53%. A. elegans and P. macrospinosa had antagonistic effects against the cucumber phytopathogenic fungi Verticillium dahliae and Fusarium oxysporum, respectively. However, A. elegans and P. macrospinosa didn't exhibit certain potential plant benefits, such as the production of hydrogen cyanide (HCN) and phosphate solubilization. The chlorophyll content and growth parameters of two-month-old cucumber plants inoculated with the fungal species were significantly better than those of the controls (non-inoculated); the shoot dry weights of inoculated plants were increased by 138% and 170% for A. elegans and P. macrospinosa, respectively; and the root colonization by fungal endophytes has also been demonstrated. In addition to the fact that P. macrospinosa has long been known as PGPF, this is the first time that the ability of A. elegans to modulate host plant growth has been demonstrated, with the potential to be used as a biofertilizer in sustainable agriculture.

Enhancing Pisum sativum growth and symbiosis under heat stress: the synergistic impact of co-inoculated bacterial consortia and ACC deaminase-lacking Rhizobium.

The 1-aminocyclopropane-1-carboxylate (ACC) deaminase is a crucial bacterial trait, yet it is not widely distributed among rhizobia. Hence, employing a co-inoculation approach that combines selected plant growth-promoting bacteria with compatible rhizobial strains, especially those lacking ACC deaminase, presents a practical solution to alleviate the negative effects of diverse abiotic stresses on legume nodulation. Our objective was to explore the efficacy of three non-rhizobial endophytes, Phyllobacterium salinisoli (PH), Starkeya sp. (ST) and Pseudomonas turukhanskensis (PS), isolated from native legumes grown in Tunisian arid regions, in improving the growth of cool-season legume and fostering symbiosis with an ACC deaminase-lacking rhizobial strain under heat stress. Various combinations of these endophytes (ST + PS, ST + PH, PS + PH, and ST + PS + PH) were co-inoculated with Rhizobium leguminosarum 128C53 or its ΔacdS mutant derivative on Pisum sativum plants exposed to a two-week heat stress period.Our findings revealed that the absence of ACC deaminase activity negatively impacted both pea growth and symbiosis under heat stress. Nevertheless, these detrimental effects were successfully mitigated in plants co-inoculated with ΔacdS mutant strain and specific non-rhizobial endophytes consortia. Our results indicated that heat stress significantly altered the phenolic content of pea root exudates. Despite this, there was no impact on IAA production. Interestingly, these changes positively influenced biofilm formation in consortia containing the mutant strain, indicating synergistic bacteria-bacteria interactions. Additionally, no positive effects were observed when these endophytic consortia were combined with the wild-type strain. This study highlights the potential of non-rhizobial endophytes to improve symbiotic performance of rhizobial strains lacking genetic mechanisms to mitigate stress effects on their legume host, holding promising potential to enhance the growth and yield of targeted legumes by boosting symbiosis.

Endophytes: a uniquely tailored source of potential antibiotic adjuvants.

Multidrug microbial resistance is risking an annual loss of more than 10 million people' lives by 2050. Solutions include the rational use of antibiotics and the use of drugs that reduce resistance or completely obliterate them. Here endophytes come to play due to their high-yield production and inherent nature to produce antimicrobial molecules. Around 40%, 45% and 17% of antibacterial agents were obtained from fungi, actinomycetes, and bacteria, respectively, whose secondary metabolites revealed effectiveness against resistant microbes such as MRSA, MRSE, and Shigella flexneri. Endophyte's role was not confined to bactericidal effect but extended to other mechanisms against MDR microbes, among which was the adjuvant role or the "magic bullets". Scarce focus was given to antibiotic adjuvants, and many laboratories today just screen for the antimicrobial activity without considering combinations with traditional antibiotics, which means real loss of promising resistance combating molecules. While some examples of synthetic adjuvants were introduced in the last decade, the number is still far from covering the disused antibiotics and restoring them back to clinical use. The data compiled in this article demonstrated the significance of quorum sensing as a foreseen mechanism for adjuvants from endophytes secondary metabolites, which call for urgent in-depth studies of their molecular mechanisms. This review, comprehensively and for the first time, sheds light on the significance of endophytes secondary metabolites in solving AMR problem as AB adjuvants.

The Indiscriminate Chemical Makeup of Secondary Metabolites Derived from Endophytes Harvested from Aloe barbadensis Miller in South Africa's Limpopo Region.

The efficacy of 23 bacterial isolates obtained from surface-sterilized stems and leaves of three medicinal plants (Aloe barbadensis Miller, Artemisia afra, and Moringa oleifera) was investigated in an endeavour to prevent the growth of Mycobacterium bovis using the cross-streak method. Endophytes were isolated by incubating sterile plant materials on nutrient agar at 30 °C for 5 days. Two isolates showing activity were subsequently utilized to produce the extracts. Whole-genome sequencing (WGC) was used to identify the isolates. Secondary metabolites produced after 7 days of growth in nutrient broth were harvested through extraction with ethyl acetate. The extracts were chemically profiled using gas chromatography-high resolution time-of-flight mass spectrometry (GC-HRTOF-MS). NCBI BLAST search results revealed that the isolated endophytes belonged to the Pseudomonas and Enterobacter genera, based on WGC. Two endophytes, Aloe I4 and Aloe I3-I5 from Aloe barbadensis, exhibited potency based on the cross-streak method. The metabolite profiling of the selected endophytes identified 34 metabolites from Aloe I4, including ergotamine, octadecane, L-proline and 143 other metabolites including quinoline and valeramide, which inhibit microbial quorum sensing. These findings suggest that bacterial endophytes from medicinal plants, particularly Aloe barbadensis, hold promise as sources of antimycobacterial agents for human health applications.

Isolation of endophytes from Dioscorea nipponica Makino for stimulating diosgenin production and plant growth.

KEY MESSAGE: Both bacterial and fungal endophytes exhibited one or more plant growth-promoting (PGP) traits. Among these strains, the Paenibacillus peoriae SYbr421 strain demonstrated the greatest activity in the direct biotransformation of tuber powder from D. nipponica into diosgenin. Endophytes play crucial roles in shaping active metabolites within plants, significantly influencing both the quality and yield of host plants. Dioscorea nipponica Makino accumulates abundant steroidal saponins, which can be hydrolyzed to produce diosgenin. However, our understanding of the associated endophytes and their contributions to plant growth and diosgenin production is limited. The present study aimed to assess the PGP ability and potential of diosgenin biotransformation by endophytes isolates associated with D. nipponica for the efficient improvement of plant growth and development of a clean and effective approach for producing the valuable drug diosgenin. Eighteen bacterial endophytes were classified into six genera through sequencing and phylogenetic analysis of the 16S rDNA gene. Similarly, 12 fungal endophytes were categorized into 5 genera based on sequencing and phylogenetic analysis of the ITS rDNA gene. Pure culture experiments revealed that 30 isolated endophytic strains exhibited one or more PGP traits, such as nitrogen fixation, phosphate solubilization, siderophore synthesis, and IAA production. One strain of endophytic bacteria, P. peoriae SYbr421, effectively directly biotransformed the saponin components in D. nipponica. Moreover, a high yield of diosgenin (3.50%) was obtained at an inoculum size of 4% after 6 days of fermentation. Thus, SYbr421 could be used for a cleaner and more eco-friendly diosgenin production process. In addition, based on the assessment of growth-promoting isolates and seed germination results, the strains SYbr421, SYfr1321, and SYfl221 were selected for greenhouse experiments. The results revealed that the inoculation of these promising isolates significantly increased the plant height and fresh weight of the leaves and roots compared to the control plants. These findings underscore the importance of preparing PGP bioinoculants from selected isolates as an additional option for sustainable diosgenin production.

Unraveling the functional characteristics of endophytic bacterial diversity for plant growth promotion and enhanced secondary metabolite production in Pelargonium graveolens.

The rich diversity of microbial endophytic communities associated with plants, often referred to as the second genome, serves as a compelling illustration of efficient co-evolution. This noteworthy partnership plays a pivotal role in sustaining plant well-being and enhancing plant adaptability across diverse habitats. Therefore, examining the diversity of endophytic microbes associated with their particular host plant is valuable for gaining insights into the vast spectrum of plant-microbe interactions. The present experiments aimed at investigating the bacterial endophytic diversity in both root and shoot tissues of Pelargonium graveolens, employing culture dependent and culture independent high-throughput metagenomics approach. A total of 614 and 620 operational taxonomic units (OTUs), encompassing 291 and 229 genera, were identified in the shoot and root tissues of P. graveolens, respectively. Furthermore, the subsequent classification of OTUs revealed 15 highly abundant phyla, with Proteobacteria dominating both root and shoot tissues. Notably, an exceptionally high abundance of Firmicutes phyla was observed in the shoot compared to the root. Additionally, 30 bacterial endophytes from the root, stem, petiole, and leaves were isolated and molecularly characterized, unveiling a consistent pattern of diversity distribution between the root and shoot of P. graveolens. Upon screening all isolates for plant growth promoting traits, Pseudomonas oryzihabitans was found to be positive for major biochemical test like nitrogen fixation, phosphate solubilization etc. and on inoculation resulted in about two-fold increase in content of essential oil accompanied by a significant rise in the geraniol and citronellol content. Diving deep into the genetic constitution of P. oryzihabitans unveiled a substantial number of genes directly and indirectly contributing to the endophyte's capability in colonizing host plants effectively. In summary, data obtained from metagenomics and culture dependent approaches including glass house trials suggest potential bacterial endophytes suitable for field applications for yield enhancement and in planta secondary metabolite enhancement investigations.

Unveiling growth-promoting attributes of peanut root endophyte Micromonospora sp.

In this study, 20 endophytic actinobacteria were isolated from different parts of peanut plants growing in cropland with low and high salt in West Bengal, India. The endophytes underwent a rigorous morphological, biochemical, and genetic screening process to evaluate their effectiveness in enhancing plant growth. About 20% of these isolates were identified as potential plant growth-promoting endophytic actinobacteria, which showed high 16S rRNA gene sequence similarity (up to 99-100%) with different species of Micromonospora. Among these isolates, Micromonospora sp. ASENR15 produced the highest levels of indole acetic acid (IAA) and gibberellic acid (GA), while Micromonospora sp. ASENL2, Micromonospora sp. ANENR4, and Micromonospora sp. ASENR12 produced the highest level of siderophore. Among these leaf and root endophytic Micromonospora, strain ANENR4 was tested for its plant growth-promoting attributes. ANENR4 can be transmitted into the roots of a healthy peanut plant, enhances growth, and colonize the roots in abundance, suggesting the potential agricultural significance of the strain. Moreover, the study is the first report of endophytic Micromonospora in peanuts with PGP effects. The outcomes of this study open avenues for further research on harnessing the benefits of this endophytic Micromonospora for optimizing plant growth in agriculture.

Cereals can trap endophytic bacteria with potential beneficial traits when grown ex-situ in harsh soils.

Microbial communities associated with plants growing in harsh conditions, including salinity and water deficiency, have developed adaptive features which permit them to grow and survive under extreme environmental conditions. In the present study, an ex-situ plant trapping method has been applied to collect the culturable microbial diversity associated with the soil from harsh and remote areas. Oryza sativa cv. Baldo and Triticum durum Primadur plants were used as recruiters, while the soil surrounding the roots of Oryza glaberrima plants from remote regions of Mali (West Africa) was used as substrate for their growth. The endophytic communities recruited by the two plant species belonged to Proteobacteria and Firmicutes, and the dominant genera were Bacillus, Kosakonia, and Enterobacter. These endophytes were characterized by analyzing some of the most common plant growth promoting traits. Halotolerant, inorganic phosphate-solubilizing and N-fixing strains were found, and some of them simultaneously showing these three traits. We verified that 'Baldo' recruited mostly halotolerant and P-solubilizers endophytes, while the endophytes selected by 'Primadur' were mainly N-fixers. The applied ex-situ plant trapping method allowed to isolate endophytes with potential beneficial traits that could be applied for the improvement of rice and wheat growth under adverse environmental conditions.

Levodopa attenuates the feed intake reduction caused by ergot alkaloids in cattle.

Consumption of ergot alkaloids from endophyte-infected tall fescue results in losses to the livestock industry in many countries and a means to mitigate these losses is needed. The objective of this study was to evaluate intra-abomasal infusion of the dopamine precursor, levodopa (L-DOPA), on dopamine metabolism, feed intake, and serum metabolites of steers exposed to ergot alkaloids. Twelve Holstein steers (344.9 ±â€…9.48 kg) fitted with ruminal cannula were housed with a cycle of heat challenge during the daytime (32 °C) and thermoneutral at night (25 °C). The steers received a basal diet of alfalfa cubes containing equal amounts of tall fescue seed composed of a mixture of endophyte-free (E-) or endophyte-infected tall fescue seeds (E+) equivalent to 15 µg ergovaline/kg body weight (BW) for 9 d followed by intra-abomasal infusion of water (L-DOPA-) or levodopa (L-DOPA+; 2 mg/kg BW) for an additional 9 d. Afterward, the steers were pair-fed for 5 d to conduct a glucose tolerance test. The E+ treatment decreased (P = 0.005) prolactin by approximately 50%. However, prolactin increased (P = 0.050) with L-DOPA+. Steers receiving E+ decreased (P < 0.001) dry matter intake (DMI); however, when supplemented with L-DOPA+ the decrease in DMI was less severe (L-DOPA × E, P = 0.003). Also, L-DOPA+ infusion increased eating duration (L-DOPA × E, P = 0.012) when steers were receiving E+. The number of meals, meal duration, and intake rate were not affected (P > 0.05) by E+ or L-DOPA+. The L-DOPA+ infusion increased (P < 0.05) free L-DOPA, free dopamine, total L-DOPA, and total dopamine. Conversely, free epinephrine and free norepinephrine decreased (P < 0.05) with L-DOPA+. Total epinephrine and total norepinephrine were not affected (P > 0.05) by L-DOPA+. Ergot alkaloids did not affect (P > 0.05) circulating free or total L-DOPA, dopamine, or epinephrine. However, free and total norepinephrine decreased (P = 0.046) with E+. Glucose clearance rates at 15 to 30 min after glucose infusion increased with L-DOPA+ (P < 0.001), but not with E+ (P = 0.280). Administration of L-DOPA as an agonist therapy to treat fescue toxicosis provided a moderate increase in DMI and eating time and increased plasma glucose clearance for cattle dosed with E+ seed.

Fescue has become the dominant cool-season perennial grass in the southeastern region of the United States and is also found in other countries. Endophytes from a plant­fungus symbiotic relationship produce toxic alkaloids that have caused significant annual economic losses to the livestock industry. Treatments to alleviate this toxicosis are still demanded. This study evaluates the infusion of the dopamine precursor, levodopa (L-DOPA), to mitigate the toxicosis caused by ergot alkaloids. When L-DOPA was infused, eating duration increased and the decrease in feed intake caused by ergot alkaloids was less severe. Additionally, circulating dopamine and glucose clearance increased with L-DOPA. These results suggest that L-DOPA has the potential to aid in the mitigation of the toxicosis caused by ergot alkaloids.

Novel report of Acinetobacter johnsonii as an indole-producing seed endophyte in Tamarindus indica L.

Plant-microbe associations have been regarded as an exciting topic of research due to their potential as environment friendly alternatives for stimulating crop growth and development. Seeds of Tamarindus indica L. have been chosen for the present study as seed endophytes prefer larger or nutritive cotyledon and hard seed coats for their colonization. The main objectives of our study were to isolate and identify the seed endophytes, their bioefficacy, and responsible chemical compounds. In a dose-dependent experiment, tamarind seed exudates (TSE) showed plant growth-promoting properties on Oryza sativa (53-81%), Daucus carota (10-31%), and Raphanus sativa (21-42%). Identification of the bacterial load in TSE through 16S rRNA sequencing revealed the existence of two bacterial species, Acinetobacter johnsonii and Niallia nealsonii. This is the first report of these two bacteria as seed endophytes of Tamarindus indica L. HRLC-MS analysis of TSE confirmed the presence of indole derivatives, primarily indole-3-lactic acid (ILA). The quantitative phytochemical estimation of bacterial culture filtrates revealed that indole-like substances were present in the extracts only in A. johnsonii at a concentration of 0.005 mg/ml of indole acetic acid equivalent. Experimental results suggested that the stimulatory activity of TSE was caused by the presence of A. johnsonii, a potential plant growth-promoting bacteria that produced indole-like compounds. This study suggests tamarind seed exudates with its endophytic microbiota as a potent plant growth-promoting agent that may find use as a cheap and sustainable source of metabolites useful in the agro-industries.

Production and bioprocessing of Taxol from Aspergillus niger, an endophyte of Encephalartos whitelockii, with a plausible biosynthetic stability: antiproliferative activity and cell cycle analysis.

The biosynthetic potency of Taxol by fungi raises their prospective to be a platform for commercial production of Taxol, nevertheless, the attenuation of its productivity with the fungal storage, is the challenge. Thus, screening for a novel fungal isolate inhabiting ethnopharmacological plants, with a plausible metabolic stability for Taxol production could be one of the most affordable approaches. Aspergillus niger OR414905.1, an endophyte of Encephalartos whitelockii, had the highest Taxol productivity (173.9 µg/L). The chemical identity of the purified Taxol was confirmed by HPLC, FTIR, and LC-MS/MS analyses, exhibiting the same molecular mass (854.5 m/z) and molecular fragmentation pattern of the authentic Taxol. The purified Taxol exhibited a potent antiproliferative activity against HepG-2, MCF-7 and Caco-2, with IC50 values 0.011, 0.016, and 0.067 µM, respectively, in addition to a significant activity against A. flavus, as a model of human fungal pathogen. The purified Taxol displayed a significant effect against the cellular migration of HepG-2 and MCF-7 cells, by ~ 52-59% after 72 h, compared to the control, confirming its interference with the cellular matrix formation. Furthermore, the purified Taxol exhibited a significant ability to prompt apoptosis in MCF-7 cells, by about 11-fold compared to control cells, suppressing their division at G2/M phase. Taxol productivity by A. niger has been optimized by the response surface methodology with Plackett-Burman Design and Central Composite Design, resulting in a remarkable ~ 1.6-fold increase (279.8 µg/L), over the control. The biological half-life time of Taxol productivity by A. niger was ~ 6 months of preservation at 4 â„ƒ, however, the Taxol yield by A. niger was partially restored in response to ethyl acetate extracts of E. whitelockii, ensuring the presence of plant-derived signals that triggers the cryptic Taxol encoding genes.

Characterization and antimicrobial activity of endophytic fungi from medicinal plant Agave americana.

Endophytic microorganisms associated with medicinal plants are of particular interest as they are a potential source of new bioactive chemicals effective against novel emerging and drug-resistant pathogens. Agave americana is a tropical medicinal plant with antibacterial, antifungal, and anticancer properties. We studied the biodiversity of fungal endophytes of A. americana and their antimicrobial production potential. Isolated endophytic fungi were classified into 32 morphotypes (15 from stem and 17 from leaf) based on their cultural and morphological characteristics. Among the fungal crude extracts tested, 82% of isolates from the leaves and 80% of the isolates from the stem showed antibacterial activity against the bacterial strains (Escherichia coli ATTC 25902, Staphylococcus aureus ATTC 14775, and Bacillus subtilis NRRL 5109) tested. Extracts from four fungal isolates from leaves showed antifungal activity against at least one of the fungal strains (Candida albicans ATTC 10231 and Aspergillus fumigatus NRRL 5109) tested. Crude extracts of seven fungal isolates showed a zone of inhibition of more than 11 mm at 10 mgml-1 against both Gram-positive and Gram-negative bacteria tested. Penicillium, Colletotrichum, Curvularia, Pleosporales, Dothideomycetes, and Pleurotus are the main endophytes responsible for bioactive potential. These results indicate that A. americana harbors endophytes capable of producing antimicrobial metabolites.

Investigation the biological activities and the metabolite profiles of endophytic fungi isolated from Gundelia tournefortii L.

Endophytic fungi are microorganisms that are considered as a potential source of natural compounds, and can be applied in various industries. The aims of this research were molecular identification of endophytic fungi isolated from the Gundelia tournefortii stems, and investigation their biological activities as well as phenolic and fatty acid profile. Surface sterilized stems of G. tournefortii were placed on potato dextrose agar (PDA) to isolate the fungal endophytes. Genomic DNA was extracted by CTAB method, and PCR amplification was performed by ITS 1 and ITS 4 as primers. The enzyme production of endophytic fungi was determined based on the formation of a clear zone that appeared around the colonies of fungus. The anti-oxidant activity was evaluated by measuring the amount of free radicals DPPH. Also, the total phenol and flavonoid contents were measured obtained by Folin-Ciocalteu and aluminum chloride colorimetric methods, respectively. Moreover, the separation and identification of phenolic acids and fatty acids were done by HPLC and GC, respectively. Phylogenetic analysis was done based on the Internal Transcribed Spacer (ITS) region, and five isolates were identified as following: Aspergillus niger, Penicillium glabrum, Alternaria alternata, A. tenuissima, and Mucor circinelloides. Evaluation of the enzymatic properties showed that P. gabrum (31 ± 1.9 mm), and A. niger (23 ± 1.7) had more ability for producing pectinase and cellulase. The anti-oxidant activity of isolates showed that A. alternata extract (IC50 = 471 ± 29 µg/mL) had the highest anti-oxidant properties, followed by A. tenuissima extract (IC50 = 512 ± 19 µg/mL). Also, the extract of A. alternata had the greatest amount of total phenols and flavonoids contents (8.2 ± 0.4 mg GAL/g and 2.3 ± 0.3 mg QE/g, respectively). The quantification analysis of phenolic acid showed that rosmarinic acid, para-coumaric acid, and meta-coumaric acid (42.02 ± 1.31, 7.53 ± 0.19, 5.41 ± 0.21 mg/g, respectively) were the main phenolic acids in the studied fungi. The analysis of fatty acids confirmed that, in all fungi, the main fatty acids were stearic acid (27.9-35.2%), oleic acid (11.3-17.3%), palmitic acid (16.9-23.2%), linoleic acid (5.8-11.6%), and caprylic acid (6.3-10.9%). Our finding showed that endophytic fungi are a source of bioactive compounds, which could be used in various industries. This is the first report of endophytic fungi associated with G. tournefortii, which provides knowledge on their future use on biotechnological processes.

Antibacterial Properties of Bacterial Endophytes Isolated from the Medicinal Plant Origanum heracleoticum L.

BACKGROUND: Bacterial endophytic communities associated with medicinal plants synthesize a plethora of bioactive compounds with biological activities. Their easy isolation and growth procedures make bacterial endophytes an untapped source of novel drugs, which might help to face the problem of antimicrobial resistance. This study investigates the antagonistic potential of endophytic bacteria isolated from different compartments of the medicinal plant O. heracleoticum against human opportunistic pathogens. METHODS: A panel of endophytes was employed in cross-streaking tests against multidrug-resistant human pathogens, followed by high-resolution chemical profiling using headspace-gas chromatography/mass spectrometry. RESULTS: Endophytic bacteria exhibited the ability to antagonize the growth of opportunistic pathogens belonging to the Burkholderia cepacia complex (Bcc). The different inhibition patterns observed were related to their taxonomic attribution at the genus level; most active strains belong to the Gram-positive genera Bacillus, Arthrobacter, and Pseudarthrobacter. Bcc strains of clinical origin were more sensitive than environmental strains. Cross-streaking tests against other 36 human multidrug-resistant pathogens revealed the highest antimicrobial activity towards the Coagulase-negative staphylococci and Klebsiella pneumoniae strains. Interestingly, strains of human origin were the most inhibited, in both groups. Concerning the production of volatile organic compounds (VOCs), the strain Arthrobacter sp. OHL24 was the best producer of such compounds, while two Priestia strains were good ketones producers and so could be considered for further biotechnological applications. CONCLUSIONS: Overall, this study highlights the diverse antagonistic activities of O. heracleoticum-associated endophytes against both Bcc and multidrug-resistant (MDR) human pathogens. These findings hold important implications for investigating bacterial endophytes of medicinal plants as new sources of antimicrobial compounds.

Unraveling endophytic diversity in dioecious Siraitia grosvenorii: implications for mogroside production.

Host and tissue-specificity of endophytes are important attributes that limit the endophyte application on multiple crops. Therefore, understanding the endophytic composition of the targeted crop is essential, especially for the dioecious plants where the male and female plants are different. Here, efforts were made to understand the endophytic bacterial composition of the dioecious Siraitia grosvenorii plant using 16S rRNA amplicon sequencing. The present study revealed the association of distinct endophytic bacterial communities with different parts of male and female plants. Roots of male and female plants had a higher bacterial diversity than other parts of plants, and the roots of male plants had more bacterial diversity than the roots of female plants. Endophytes belonging to the phylum Proteobacteria were abundant in all parts of male and female plants except male stems and fruit pulp, where the Firmicutes were most abundant. Class Gammaproteobacteria predominated in both male and female plants, with the genus Acinetobacter as the most dominant and part of the core microbiome of the plant (present in all parts of both, male and female plants). The presence of distinct taxa specific to male and female plants was also identified. Macrococcus, Facklamia, and Propionibacterium were the distinct genera found only in fruit pulp, the edible part of S. grosvenorii. Predictive functional analysis revealed the abundance of enzymes of secondary metabolite (especially mogroside) biosynthesis in the associated endophytic community with predominance in roots. The present study revealed bacterial endophytic communities of male and female S. grosvenorii plants that can be further explored for monk fruit cultivation, mogroside production, and early-stage identification of male and female plants. KEY POINTS: • Male and female Siraitia grosvenorii plants had distinct endophytic communities • The diversity of endophytic communities was specific to different parts of plants • S. grosvenorii-associated endophytes may be valuable for mogroside biosynthesis and monk fruit cultivation.

Current Status and Future Perspectives on Distribution of Fungal Endophytes and Their Utilization for Plant Growth Promotion and Management of Grapevine Diseases.

Grapevine is one of the economically most important fruit crops cultivated worldwide. Grape production is significantly affected by biotic constraints leading to heavy crop losses. Changing climatic conditions leading to widespread occurrence of different foliar diseases in grapevine. Chemical products are used for managing these diseases through preventive and curative application in the vineyard. High disease pressure and indiscriminate use of chemicals leading to residue in the final harvest and resistance development in phytopathogens. To mitigate these challenges, the adoption of potential biocontrol control agents is necessary. Moreover, multifaceted benefits of endophytes made them eco-friendly, and environmentally safe approach. The genetic composition, physiological conditions, and ecology of their host plant have an impact on their dispersion patterns and population diversity. Worldwide, a total of more than 164 fungal endophytes (FEs) have been characterized originating from different tissues, varieties, crop growth stages, and geographical regions of grapevine. These diverse FEs have been used extensively for management of different phytopathogens globally. The FEs produce secondary metabolites, lytic enzymes, and organic compounds which are known to possess antimicrobial and antifungal properties. The aim of this review was to understand diversity, distribution, host-pathogen-endophyte interaction, role of endophytes in disease management and for enhanced, and quality production.