Enhanced camptothecin production by ethanol addition in the suspension culture of the endophyte, Fusarium solani

Bioprocessing of camptothecin from Alternaria brassicicola, an endophyte of Catharanthus roseus, with a strong antiproliferative activity and inhibition to Topoisomerases

Suppression of fungal camptothecin (CPT) biosynthesis with the preservation and successive subculturing is the challenge that impedes fungi from the industrial application, so, screening for a novel fungal isolate with a conceivable stable producing potency of CPT was the main objective of this work. Catharanthus roseus with diverse contents of bioactive metabolites could have a plethora of novel endophytes with unique metabolic properties. Among the endophytes of C. roseus, Alternaria brassicicola EFBL-NV OR131587.1 was the highest CPT producer (96.5 μg/L). The structural identity of the putative CPT was verified by HPLC, FTIR, HNMR and LC-MS/MS, with a molecular mass 349 m/z, and molecular fragmentation patterns that typically identical to the authentic one. The purified A. brassicicola CPT has a strong antiproliferative activity towards UO-31 (0.75 μM) and MCF7 (3.2 μM), with selectivity index 30.8, and 7.1, respectively, in addition to resilient activity to inhibit Topo II (IC50 value 0.26 nM) than Topo 1 (IC50 value 3.2 nM). The purified CPT combat the wound healing of UO-31 cells by ~ 52%, stops their matrix formation, cell migration and metastasis. The purified CPT arrest the cellular division of the UO-31 at the S-phase, and inducing their cellular apoptosis by ~ 20.4 folds, compared to the control cells. Upon bioprocessing with the surface response methodology, the CPT yield by A. brassicicola was improved by ~ 3.3 folds, compared to control. The metabolic potency of synthesis of CPT by A. brassicicola was attenuated with the fungal storage and subculturing, losing ~ 50% of their CPT productivity by the 6th month of storage and 6th generation. Practically, the CPT productivity of the attenuated A. brassicicola was restored by addition of 1% surface sterilized leaves of C. roseus, ensuring the eliciting of cryptic gene cluster of A. brassicicola CPT via the plant microbiome-A. brassicicola interactions. So, for the first time, a novel endophytic isolate A. brassicicola, from C. roseus, was explored to have a relatively stable CPT biosynthetic machinery, with an affordable feasibility to restore their CPT productivity using C. roseus microbiome, in addition to the unique affinity of the extracted CPT to inhibit Topoisomerase I and II.

Proteomics and metabolomics analyses of camptothecin-producing Aspergillus terreus reveal the integration of PH domain-containing proteins and peptidylprolyl cis/trans isomerase in restoring the camptothecin biosynthesis

IMPORTANCE

Decreasing the camptothecin productivity by fungi with storage and subculturing is the challenge that halts their further implementation to be an industrial platform for camptothecin (CPT) production. The highest differentially abundant proteins were Pleckstrin homology (PH) domain-containing proteins and Peptidyl-prolyl cis/trans isomerase that fluctuated with the subculturing of A. terreus with a remarkable relation to CPT biosynthesis and restored with addition of F. elastica microbiome.

Production, bioprocessing and antiproliferative activity of camptothecin from Aspergillus terreus, endophyte of Cinnamomum camphora: restoring their biosynthesis by indigenous microbiome of C. camphora

Fungal producing potency of camptothecin (CPT) raise the hope for their usage to be a platform for industrial production of CPT, nevertheless, attenuation of their productivity of CPT with the subculturing and preservation is the challenge. So, screening for novel endophytic fungal isolates with a reliable CPT-biosynthetic stability was the objective. Among the isolated endophytic fungi from the tested medicinal plants, Aspergillus terreus OQ642314.1, endophyte of Cinnamomum camphora, exhibits the highest yield of CPT (89.4 μg/l). From the NMR, FT-IR and LC-MS/MS analyses, the extracted CPT from A. terreus gave the same structure and molecular mass fragmentation pattern of authentic CPT (349 m/z). The putative CPT had a significant activity against MCF7 (0.27 µM) and HEPG-2 (0.8 µM), with a strong affinity to inhibits the human Topoisomerase 1 activity (IC50 0.362 μg/ml) as revealed from the Gel-based DNA relaxation assay. The purified CPT displayed a strong antimicrobial activity for various bacterial (E. coli and B. cereus) and fungal (A. flavus and A. parasiticus) isolates, ensuring the unique tertiary, and stereo-structure of A. terreus for penetrating the microbial cell walls and targeting the topoisomerase I. The higher dual activity of the purified CPT as antimicrobial and antitumor, emphasize their therapeutic efficiency, especially with growth of the opportunistic microorganisms due to the suppression of human immune system with the CPT uses in vivo. The putative CPT had an obvious activity against the tumor cell (MCF7) metastasis, and migration as revealed from the wound healing assay. The overall yield of A. terreus CPT was maximized with the Blackett-Burman design by twofolds increment (164.8 μg/l). The CPT yield by A. terreus was successively diminished with the multiple fungal subculturing, otherwise, the CPT productivity of A. terreus was restored, and increased over the zero culture upon coculturing with C. camphora microbiome (1.5% w/v), ensuring the restoring of CPT biosynthetic potency of A. terreus by the plant microbiome-derived chemical signals "microbial communication". This is the first report exploring the feasibility of A. terreus "endophyte of C. camphora" to be a preliminary platform for commercial production of CPT with a reliable sustainability upon uses of indigenous C. camphora microbiome.

Production, Bioprocessing and Anti-Proliferative Activity of Camptothecin from Penicillium chrysogenum, "An Endozoic of Marine Sponge, Cliona sp.", as a Metabolically Stable Camptothecin Producing Isolate

Exploring the metabolic potency of fungi as camptothecin producers raises the hope of their usage as an industrial source of camptothecin, due to their short-life span and the feasibility of metabolic engineering. However, the tiny yield and loss of camptothecin productivity of fungi during storage and sub-culturing are challenges that counteract this approach. Marine fungi could be a novel source for camptothecin production, with higher yield and reliable metabolic sustainability. The marine fungal isolate Penicillium chrysogenum EFBL # OL597937.1 derived from the sponge "Cliona sp." has been morphologically identified and molecularly confirmed, based on the Internal Transcribed Spacer sequence, exhibiting the highest yield of camptothecin (110 μg/L). The molecular structure and chemical identity of P. chrysogenum derived camptothecin has been resolved by HPLC, FTIR and LC-MS/MS analyses, giving the same spectroscopic profiles and mass fragmentation patterns as authentic camptothecin. The extracted camptothecin displayed a strong anti-proliferative activity towards HEP-2 and HCT-116 (IC₅₀ values 0.33-0.35 µM). The yield of camptothecin was maximized by nutritional optimization of P. chrysogenum with a Plackett-Burman design, and the productivity of camptothecin increased by 1.8 fold (200 µg/L), compared to control fungal cultures. Upon storage at 4 °C as slope culture for 8 months, the productivity of camptothecin for P. chrysogenum was reduced by 40% compared to the initial culture. Visual fading of the mycelial pigmentation of P. chrysogenum was observed during fungal storage, matched with loss of camptothecin productivity. Methylene chloride extracts of Cliona sp. had the potency to completely restore the camptothecin productivity of P. chrysogenum, ensuring the partial dependence of the expression of the camptothecin biosynthetic machinery of P. chrysogenum on the chemical signals derived from the sponge, or the associated microbial flora. This is the first report describing the feasibility of P. chrysogenum, endozoic of Cliona sp., for camptothecin production, along with reliable metabolic biosynthetic stability, which could be a new platform for scaling-up camptothecin production.

Plant-microbe interactions implicated in the production of camptothecin - An anticancer biometabolite from Phyllosticta elongata MH458897 a novel endophytic strain isolated from medicinal plant of Western Ghats of India

Endophytic wild fungal strain Phyllosticta elongata MH458897 isolated from medicinal plant Cipadessa baccifera from the Western Ghats region of Sathyamangalam Tiger Reserve Forest. This endophytic fungus has potential of effective anticancer drug Camptothecin (CPT). Endophytic fungi act as key symbionts in-between plants and ecosystem in the biosphere. This recently identified microbial population inside the plants produces many defence metabolites against plant pathogens. Among these defense metabolites, CPT gained much attention because of its effective anticancer activity. The maximum yield of CPT produced by optimizing the various factors like DEKM07 medium, pH 5.6, incubation time using Response Surface Methodology based on Central Composite Design. Extracted CPT is characterized using High Performance Liquid Chromatography and Electrospray ionization-Mass spectrometry. The highest yield of CPT was 0.747 mg/L was produced at optimized factors of dextrose - 50 g L^-1, peptone - 5.708 g L^-1, magnesium sulphate - 0.593 g L^-1, and incubation time - 14 days. In-vitro MTT assay revealed the CPT derivatives were cytotoxic to A-549 cancer cell line (IC₅₀ 58.28 μg/ml) as nearly compared to the (IC₅₀ 51.08 μg/ml) standard CPT. CPT producing strain P. elongata from C. baccifera has the potential of CPT biosynthesis, and could be an effective anticancer bio metabolite. This compound has been described in the literature to be an effective anticancer metabolite. Our findings support the novel lifesaving anticancer drug from endophytic fungus in forest ecosystem concludes effective utilization of key symbionts will safeguard the humans and forest ecosystem.

Endophytic fungus Diaporthe caatingaensis MT192326 from Buchanania axillaris: An indicator to produce biocontrol agents in plant protection

The study aims at the Isolation, screening and antibacterial evaluation of Camptothecin (CPT) and its derivatives, an anticancer molecule from endophytic fungus Diaporthe caatingaensis MT192326 of the medicinal plant, Buchanania axillaris. Plant parts were collected from Sathyamangalam Tiger Reserve forest, Tamil Nadu. The fungus was isolated using DEKM07 medium was used as the screening medium for the presence of CPT. The strain with the highest yield of CPT was identified at the molecular level by 18S rDNA sequencing. CPT was isolated and analyzed by UV-Vis spectrophotometry, Thin layer chromatography, High-Performance Liquid Chromatography, Fourier Transform Infrared spectroscopy, and Electron spray ionization-mass spectrometry. The compounds identified by ESI-MS from the fungal extract were studied for their antibacterial assays against procured MTCC bacterial pathogens. The maximum yield of 0.681 mg/L of CPT was produced by the fungus D.caatingaensis. CPT derivatives were identified at m/z of 305, 348 and 389 through ESI-MS analysis. Antibacterial studies revealed that the endophytic fungal extract compounds were studied for antibacterial activities of disc diffusion assay, exhibiting a growth inhibition range of 15-22 mm in nutrient agar plate medium. The Minimum Inhibitory Concentration revealed the antibacterial potential at a lower concentration of 12.5-25 μg/ml with all bacteria studied. The relatively lower antimicrobial efficacy of partially purified bio-metabolites than the positive control streptomycin (3.125) concentration could be due to the presence of derivatives of the compounds that hinder the activity of the biometabolite. This is the first initiative to screen, isolate and analyze the antibacterial assays of CPT and derivatives from endophytic fungus D.caatingaensis of ethnopharmacologically important B.axillaris plant from STRF.

Biologically Significant and Recently Isolated Alkaloids from Endophytic Fungi

A selection of the established and recently characterized alkaloids from the exploration of plant- and some marine-associated endophytic fungi is reviewed, with reference to alkaloids of biological significance.

Current advances of endophytes as a platform for production of anti-cancer drug camptothecin

Camptothecin (CPT), a well-known monoterpenoid indole alkaloid with broad-spectrum anti-cancer activity, is produced from plants and endophytes. In view of the limitations of plants as sources of camptothecin in productivity and efficiency, endophytes serve as the fast growth, high cost-effectiveness, good reproducibility, and feasible genetic manipulation, so they have the potential to meet the huge market demand of the pharmaceutical industry. In this review, we summarized the isolation, identification and fermentation of CPT-producing endophytes, as well as the biosynthesis, extraction and detection of camptothecin from endophytes. Among them, we put emphasis on increasing the production of camptothecin in endophytes through different strategies such as changing the proportion of carbon, nitrogen and phosphate source, adding the precursors, elicitors or adsorbent resin, utilizing co-culture fermentation or fermenter culture. However, cell subculture and metabolic reprogramming affect the expression of camptothecin biosynthetic genes in CPT-producing endophytes, which poses a challenge to the industrial production of camptothecin. Therefore, it will be useful to gain insights through the review of these researches and provide alternative approaches to develop economical, eco-friendly and reliable natural products.

Sustainable production of camptothecin from an Alternaria sp. isolated from Nothapodytes nimmoniana

Camptothecin the third most in demand alkaloid, is commercially extracted in India from the endangered plant, Nothapodytes nimmoniana. Endophytes, the microorganisms that reside within plants, are reported to have the ability to produce host-plant associated metabolites. Hence, our research aims to establish a sustainable and high camptothecin yielding endophyte, as an alternative source for commercial production of camptothecin. A total of 132 endophytic fungal strains were isolated from different plant parts (leaf, petiole, stem and bark) of N. nimmoniana, out of which 94 were found to produce camptothecin in suspension culture. Alternaria alstroemeriae (NCIM1408) and Alternaria burnsii (NCIM1409) demonstrated camptothecin yields up to 426.7 ± 33.6 µg/g DW and 403.3 ± 41.6 µg/g DW, respectively, the highest reported production to date. Unlike the reported product yield attenuation in endophytes with subculture in axenic state, Alternaria burnsii NCIM1409 could retain and sustain the production of camptothecin up to ~ 200 μg/g even after 12 continuous subculture cycles. The camptothecin biosynthesis in Alternaria burnsii NCIM1409 was confirmed using 13C carbon labelling (and cytotoxicity analysis on different cancer cell lines) and this strain can now be used to develop a sustainable bioprocess for in vitro production of camptothecin as an alternative to plant extraction.

Dynamics of Chemical Diversity during Co-Cultures: An Integrative Time-Scale Metabolomics Study of Fungal Endophytes Cophinforma mamane and Fusarium solani

A rapid and efficient metabolomic study of Cophinforma mamane and Fusarium solani co-cultivation in time-series based analysis was developed to study metabolome variations during their fungal interactions. The fungal metabolomes were studied through the integration of four metabolomic tools: MS-DIAL, a chromatographic deconvolution of liquid-chromatography-mass spectrometry (LC/MS); MS-FINDER, a structure-elucidation program with a wide range metabolome database; GNPS, an effective method to organize MS/MS fragmentation spectra, and MetaboAnalyst, a comprehensive web application for metabolomic data analysis and interpretation. Co-cultures of C. mamane and F. solani induced different patterns of metabolite production over 10 days of incubation and induced production of five de novo compounds not occurring in monocultures. These results emphasize that co-culture in time-frame analysis is an interesting method to unravel hidden metabolome in the investigation of fungal chemodiversity.

Distribution of camptothecin biosynthetic intermediates and identification the rate-limiting step of camptothecin biosynthesis

Two key biosynthetic intermediates (pumiloside and strictosamide) of camptothecin were isolated. A high performance liquid chromatography-ultraviolet (HPLC-UV) method was developed to determine four main alkaloid compounds (pumiloside, strictosamide, camptothecin and 10-hydroxycamptothecin) and estimate two minor compounds (deoxypumiloside, 9-methoxycamptothecin) simultaneously in different parts of Camptotheca acuminata, with a good linearity and R² > 0.999 for all curves. The results indicated that there was a positive correlation between the two key intermediates (strictosamide and pumiloside) and camptothecin in vivo. The speculation that the root was the synthetic position of camptothecin in vivo was confirmed. The rate-limiting step of camptothecin biosynthesis was estimated the step from pumiloside to deoxypumiloside based on its concentration fall sharply.

Factors Affecting the Metabolite Productions in Endophytes: Biotechnological Approaches for Production of Metabolites

Since 1980, many species and different strains from endophytic genera of Phomopsis, Fusarium, Pestaliopsis and Aspergillus have been studied because of their ability to produce medicinal compounds found in their host plants. Some of these medicinal agents such as Taxol, Brefeldine A, Camptothecin and Podophyllotoxin are being produced in large-scale after an optimization process. However, the potential of fungal endophytes to produce host-like medicinal compounds remains largely unexplored.

New synergistic co-culture of Corylus avellana cells and Epicoccum nigrum for paclitaxel production

Paclitaxel is a main impressive chemotherapeutic agent with unique mode of action and broad-spectrum activity against cancers. Hazel (Corylus avellana) is a paclitaxel-producing species through bioprospection. Endophytic fungi have significant roles in plant paclitaxel production. This study evaluated the effect of co-culture of C. avellana cells and paclitaxel-producing endophytic fungus, Epicoccum nigrum strain YEF₂ and also the effect of elicitors derived from this fungal strain on paclitaxel production. The results clearly revealed that co-culture of C. avellana cells and E. nigrum was more effective than elicitation of C. avellana cells by only cell extract or culture filtrate of this fungal strain. Co-culture of C. avellana cells and E. nigrum surpassed monocultures in terms of paclitaxel production designating their synergistic interaction potential. Fungal inoculum amount, co-culture establishment time and co-culture period were important factors for achieving the maximum production of paclitaxel in this co-culture system. The highest total yield of paclitaxel (404.5 µg L^-1) was produced in co-culture established on 13th day using 3.2% (v/v) of E. nigrum mycelium suspension, which was about 5.5 and 136.6 times that in control cultures of C. avellana cells and E. nigrum, respectively. This is the first report on positive effect of co-culture of paclitaxel-producing endophytic fungus and non-host plant cells for enhancing paclitaxel production.

Genomic sequencing, genome-scale metabolic network reconstruction, and in silico flux analysis of the grape endophytic fungus Alternaria sp. MG1

BACKGROUND

Alternaria sp. MG1, an endophytic fungus isolated from grape, is a native producer of resveratrol, which has important application potential. However, the metabolic characteristics and physiological behavior of MG1 still remains mostly unraveled. In addition, the resveratrol production of the strain is low. Thus, the whole-genome sequencing is highly required for elucidating the resveratrol biosynthesis pathway. Furthermore, the metabolic network model of MG1 was constructed to provide a computational guided approach for improving the yield of resveratrol.

RESULTS

Firstly, a draft genomic sequence of MG1 was generated with a size of 34.7 Mbp and a GC content of 50.96%. Genome annotation indicated that MG1 possessed complete biosynthesis pathways for stilbenoids, flavonoids, and lignins. Eight secondary metabolites involved in these pathways were detected by GC-MS analysis, confirming the metabolic diversity of MG1. Furthermore, the first genome-scale metabolic network of Alternaria sp. MG1 (named iYL1539) was reconstructed, accounting for 1539 genes, 2231 metabolites, and 2255 reactions. The model was validated qualitatively and quantitatively by comparing the in silico simulation with experimental data, and the results showed a high consistency. In iYL1539, 56 genes were identified as growth essential in rich medium. According to constraint-based analysis, the importance of cofactors for the resveratrol biosynthesis was successfully demonstrated. Ethanol addition was predicted in silico to be an effective method to improve resveratrol production by strengthening acetyl-CoA synthesis and pentose phosphate pathway, and was verified experimentally with a 26.31% increase of resveratrol. Finally, 6 genes were identified as potential targets for resveratrol over-production by the recently developed methodology. The target-genes were validated using salicylic acid as elicitor, leading to an increase of resveratrol yield by 33.32% and the expression of gene 4CL and CHS by 1.8- and 1.6-fold, respectively.

CONCLUSIONS

This study details the diverse capability and key genes of Alternaria sp. MG1 to produce multiple secondary metabolites. The first model of the species Alternaria was constructed, providing an overall understanding of the physiological behavior and metabolic characteristics of MG1. The model is a highly useful tool for enhancing productivity by rational design of the metabolic pathway for resveratrol and other secondary metabolites.

Elicitors Derived from Hazel (Corylus avellana L.) Cell Suspension Culture Enhance Growth and Paclitaxel Production of Epicoccum nigrum

The microbial fermentation is considered as the potential source for large-scale production of paclitaxel. Since co-cultivation/mixed fermentation strategy has been reported as a yield enhancement strategy for paclitaxel production, investigation of fungal endophyte response to plant culture medium, plant cell extract (CE) and medium filtrate (MF) of plant cell suspension culture in terms of growth and paclitaxel production is interesting. In this study, 35 endophytic fungi were isolated from Taxus baccata and Corylus avellana grown in Iran. The analysis of high-performance liquid chromatography and mass spectrometry showed that one isolate (YEF2) produced paclitaxel. The isolate YEF2 was identified as Epicoccum nigrum by sequencing of ITS1-5.8S-ITS2 rDNA region and actin gene. YEF2 was slow-growing in Murashige and Skoog medium, but the synergistic interaction of gibberellic acid (GA3) and CE of C. avellana enhanced the growth of YEF2. The highest total yield of paclitaxel (314.7 µg/l; 11.5-folds) of E. nigrum strain YEF2 was obtained by using 28% (v/v) filter sterilized CE of C. avellana and 2 µg ml-1 GA3 that was significantly higher than the control. In this study, the effects of the plant cell extract on growth and paclitaxel production of paclitaxel producing endophytic fungus were studied for the first time.

Production of bioproducts by endophytic fungi: chemical ecology, biotechnological applications, bottlenecks, and solutions

Endophytes are microorganisms that colonize the interior of host plants without causing apparent disease. They have been widely studied for their ability to modulate relationships between plants and biotic/abiotic stresses, often producing valuable secondary metabolites that can affect host physiology. Owing to the advantages of microbial fermentation over plant/cell cultivation and chemical synthesis, endophytic fungi have received significant attention as a mean for secondary metabolite production. This article summarizes currently reported results on plant-endophyte interaction hypotheses and highlights the biotechnological applications of endophytic fungi and their metabolites in agriculture, environment, biomedicine, energy, and biocatalysts. Current bottlenecks in industrial development and commercial applications as well as possible solutions are also discussed.

Strategies to enhance the production of pinoresinol and its glucosides by endophytic fungus (Phomopsis sp. XP-8) isolated from Tu-chung bark

To improve the production yield of (+)-pinoresinol (Pin), (+)-pinoresinol monoglucoside (PMG), and (+)-pinoresinol diglucoside (PDG), different methods were conducted, including co-culture with resveratrol-producing Alternaria sp. MG1 spores and addition of Tu-chung in a medium at the start of cultivation, ultrasound treatment (40 kHZ, 10 min) on 5-day culture, and addition of ethanol and sodium butyrate on Day 3, followed by cultivation for an additional period of 2 days. At the end of the cultivation period (5 days), the liquid phase was collected for product analysis. Cells were collected for the determination of gene expression levels and then used in bioconversion using resting cells for another period of 2 days. The liquid phase was measured to determine the output of the target products and the expression levels of the key genes related to the biosynthesis of these compounds. Consequently, co-culture with Alternaria MG1 and addition of Tu-chung bark in the medium efficiently increased Pin, PMG, and PDG production yield in the biosynthesis systems using potato dextrose broth medium and resting cells of Phomopsis sp. XP-8. The key genes related to the biosynthesis of these compounds were significantly upregulated. However, in the majority of cases, the addition of ethanol and sodium butyrate, and ultrasound treatment decreased the production yield of Pin, PMG, and PDG. The change in production yield was not consistently accompanied by a change in gene expression.

Expression and functional analysis of the lysine decarboxylase and copper amine oxidase genes from the endophytic fungus Colletotrichum gloeosporioides ES026

Huperzine A (HupA) isolated from Huperzia serrata is an important compound used to treat Alzheimer's disease (AD). Recently, HupA was reported in various endophytic fungi, with Colletotrichum gloeosporioides ES026 previously isolated from H. serrata shown to produce HupA. In this study, we performed next-generation sequencing and de novo RNA sequencing of C. gloeosporioides ES026 to elucidate the molecular functions, biological processes, and biochemical pathways of these unique sequences. Gene ontology and Kyoto Encyclopedia of Genes and Genomes assignments allowed annotation of lysine decarboxylase (LDC) and copper amine oxidase (CAO) for their conversion of L-lysine to 5-aminopentanal during HupA biosynthesis. Additionally, we constructed a stable, high-yielding HupA-expression system resulting from the overexpression of CgLDC and CgCAO from the HupA-producing endophytic fungus C. gloeosporioides ES026 in Escherichia coli. Quantitative reverse transcription polymerase chain reaction analysis confirmed CgLDC and CgCAO expression, and quantitative determination of HupA levels was assessed by liquid chromatography high-resolution mass spectrometry, which revealed that elevated expression of CgLDC and CgCAO produced higher yields of HupA than those derived from C. gloeosporioides ES026. These results revealed CgLDC and CgCAO involvement in HupA biosynthesis and their key role in regulating HupA content in C. gloeosporioides ES026.

Characterization and antitumor activity of camptothecin from endophytic fungus Fusarium solani isolated from Camptotheca acuminate

BACKGROUND

Camptothecin (CPT) is a potent drug against cancers, originally from plants. The endophytic fungi could produce the secondary metabolite same as the host and is used as medicine.

OBJECTIVES

The aim of this paper was to investigate an endophytic fungal CPT with anti-neoplastic activity.

METHODS

Endophytic fungi were isolated from Camptotheca acuminata in China. CPT from strain S-019 was characterized by TLC, HPLC and EI-MS analysis. Anti-tumor activity of fungal CPT was detected by MTT and fluorescent dye methods using Vero and PC-3 cells.

RESULTS

A total of 94 endophytic fungi strains were isolated from tissues of C. acuminata and 16 fungi strains displayed cytotoxic activity on Vero or PC3 cells. Of which, the fungal strain S-019, classified as Fusarium solani, displayed impressive cytotoxic activity on cancer cells and was found to produce CPT by analysis of TLC, HPLC and EI-MS methods. Bioassay studies confirmed that the fungi CPT had potent cytotoxicity on Vero cells and induced apoptosis of Vero cells.

CONCLUSION

The endophytic fungi from camptotheca trees are a reliable source for natural anticancer compounds. The endophytic fungi could produce CPT same as plant. The fungal CPT exhibited effective activity at inhibiting cell growth and inducing apoptosis on Vero cells.

Endophytic Bacteria Isolated from Panax ginseng Improves Ginsenoside Accumulation in Adventitious Ginseng Root Culture

Ginsenoside is the most important secondary metabolite of ginseng. Natural sources of wild ginseng have been overexploited. Although root culture could reduce the length of the growth cycle of ginseng, the number of ginsenosides is fewer and their contents are lower in adventitious roots of ginseng than that in ginseng cultivated in the field. In this study, we investigated the effects of endophytic bacterial elicitors on biomass and ginsenoside production in adventitious roots cultures of Panax ginseng. Endophyte LB 5-3 as an elicitor could increase biomass and ginsenoside accumulation in ginseng adventitious root culture. After 6 days elicitation with a 10.0 mL of strain LB 5-3, the content of total ginsenoside was 2.026 mg g⁻¹ which was four times more than that in unchallenged roots. The combination of methyl jasmonate and strain LB 5-3 had a negative effect on ginseng adventitious root growth and ginsenoside production. The genomic DNA of strain LB 5-3 was sequenced, and was found to be most closely related to Bacillus altitudinis (KX230132.1). The challenged ginseng adventitious root extracts exerted inhibitory effect against the HepG2 cells, which IC₅₀ value was 0.94 mg mL⁻¹.

Reprint of: Effect of fermentation parameters, elicitors and precursors on camptothecin production from the endophyte Fusarium solani

Volumetric productivity of camptothecin from the suspension culture of the endophyte Fusarium solani was enhanced up to ∼152 fold (from 0.19μgl(-1)d(-1) to 28.9μgl(-1)d(-1)) under optimized fermentation conditions including initial pH (6.0), temperature (32°C) and agitation speed (80rpm) with (5% (v/v)) ethanol as medium component. Among various elicitors and precursors studied, tryptamine (0.5mM) as precursor and bovine serum albumin (BSA) (0.075mM) as an elicitor added on day 6 of the cultivation period resulted in maximum enhancement of camptothecin concentration (up to 4.5 and 3.4-fold, respectively). These leads provide immense scope for further enhancement in camptothecin productivity at bioreactor level. The cytotoxicity analysis of the crude camptothecin extract from the fungal biomass revealed its high effectiveness against colon and mammary gland cancer cell lines.

Production of naphthoquinones and phenolics by a novel isolate Fusarium solani PSC-R of Palk Bay and their industrial applications

The present study was attempted to enhance the production of naphthoquinones and phenolics by Fusarium solani PSC-R of Palk Bay origin, which exhibited potent antibacterial, antioxidant and dyeing activity. Maximum productivity of naphthoquinones and phenolics was achieved in potato infusion medium supplemented with 2% sucrose. Addition of nitrogen sources to the medium adversely affected the production of both naphthoquinones and phenolics. An initial pH of 5 and incubation at 31°C for six days at 140rpm was found to increase the yield (123.65mg/g of DW), concentration (867.33mg/l) and total naphthoquinones (602.8μM/g DW) by 7.58, 10.44 and 3.68-fold respectively. Similarly, the antioxidant and antibacterial activity associated with the phenolics of PSC-R increased by 1.5-fold in the optimized medium. The obtained results document the effective means of enhanced production of naphthoquinones and phenolics in the suspension culture of F. solani PSC-R at bioreactor level.

Effect of fermentation parameters, elicitors and precursors on camptothecin production from the endophyte Fusarium solani

Volumetric productivity of camptothecin from the suspension culture of the endophyte Fusarium solani was enhanced up to ∼152 fold (from 0.19 μg l(-1) d(-1) to 28.9 μg l(-1) d(-1)) under optimized fermentation conditions including initial pH (6.0), temperature (32 °C) and agitation speed (80 rpm) with (5% (v/v)) ethanol as medium component. Among various elicitors and precursors studied, tryptamine (0.5 mM) as precursor and bovine serum albumin (BSA) (0.075 mM) as an elicitor added on day 6 of the cultivation period resulted in maximum enhancement of camptothecin concentration (up to 4.5 and 3.4-fold, respectively). These leads provide immense scope for further enhancement in camptothecin productivity at bioreactor level. The cytotoxicity analysis of the crude camptothecin extract from the fungal biomass revealed its high effectiveness against colon and mammary gland cancer cell lines.

Endophytes as in vitro production platforms of high value plant secondary metabolites

Many reports have been published on bioprospecting of endophytic fungi capable of producing high value bioactive molecules like, paclitaxel, vincristine, vinblastine, camptothecin and podophyllotoxin. However, commercial exploitation of endophytes for high value-low volume plant secondary metabolites remains elusive due to widely reported genomic instability of endophytes in the axenic culture. While most of the endophyte research focuses on screening endophytes for novel or existing high value biomolecules, very few reports seek to explore the possible mechanisms of production of host-plant associated or novel secondary metabolites in these organisms. With an overview of host-endophyte relationship and its possible impact on the secondary metabolite production potential of endophytes, the review highlights the evidence reported for and against the presence of host-independent biosynthetic machinery in endophytes. The review aims to address the question, why should and how can endophytes be exploited for large scale in vitro production of high value phytochemicals? In this regard, various bioprocess optimization strategies that have been applied to sustain and enhance the product yield from the endophytes have also been described in detail. Further, techniques like mixed fermentation/co-cultivation and use of epigenetic modifiers have also been discussed as potential strategies to activate cryptic gene clusters in endophytes, thereby aiding in novel metabolite discovery and overcoming the limitations associated with axenic culture of endophytes.