Diversity and extracellular enzyme activities of fungal endophytes isolated from medicinal plants of Western Ghats, Karnataka

A total of 112 endophytic fungi belonging to 26 genera were isolated from six wild medicinal plants belonging to Bisle region, Western Ghats of Karnataka, among which Hedychium flavescens Carey ex Roscoe and Hedychium coronarium J. Koenig are listed as endangered plants in the Red data book. The endophytic fungal diversity and extracellular enzyme activity from the endangered plants are reported for the first time. The diversity of the fungal isolates was analyzed using Simpson’s diversity indices, Shannon–Weiner index and Evenness. The fungal isolates were screened for the production of extracellular enzymes, of which 29% were positive for amylase, 28% for cellulase, 18% for pectinase and 40% for asparaginase activity. None of the endophytic isolates depicted laccase activity

Induction of Systemic Resistance by Trichoderma Asperellum against Bacterial Wilt of Tomato Caused by Ralstonia Solanacearum

Trichoderma asperellum was used as a biological control agent against bacterial wilt disease caused by Ralstonia solanacearum. The present investigation is focused on the role of defense- related enzymes in imparting resistance to tomato against bacterial wilt pathogen Ralstonia solanacearum. Two isolates of Trichoderma asperellum (T4 and T8) exhibiting high antagonistic activity against a virulent strain of Ralstonia solanacearum (RS) were selected during screening for studies on several biocontrol mechanisms under greenhouse conditions. Seed treatment with T. asperellum isolates significantly improved the quality of seed germination and seedling vigor. Efficacy of T4 and T8 isolates, evaluated under greenhouse conditions exhibited suppression by about 50% in disease incidence of bacterial wilt and promoted growth in tomato plant. The isolates T4 and T8 were further tested for their ability to induce the production of defense-related enzymes in plants. The seed application with T4 and T8 isolates induced a significant increase in the activities of peroxidase (POX), Polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), and â.1, 3-glucanase in treated tomato plants. Increased activities of phenylalanine ammonia lyase, peroxidase, Polyphenol oxidase, â-1, 3-glucanase were observed in T4 and T8 pre-treated tomato plants challenged with Ralstonia solanacearum. Trichoderma asperellum treatment also triggered the defense related enzymes involved in synthesis of phenols. Higher accumulation of phenolics was noticed in plants pre-treated with T4 and T8 challenged with Ralstonia solanacearum. Native PAGE analysis of both peroxidase (POX) and Polyphenol oxidase (PPO) was carried out for the time course of enzyme activities. The present study shows that in addition to direct antagonism and plant growth promotion; induction and increased activity of defense related enzymes involved in the phenyl propanoid pathway collectively contributed to enhanced resistance against invasion of bacterial wilt in tomato caused by Ralstonia solanacearum

Optimization of physiological conditions for L-asparaginase production by endophytic fungi (Fusarium solani) isolated from Tinospora cordifolia (Willd.) Hook. F & Thomson

Asparaginase converts L-asparagine to L-aspartic acid and has received considerable attention in the recent years for its anti-carcinogenic potential. In the present investigation, the endophytic fungi isolated from T. cordifolia were screened for the production of extracellular L-asparaginase during their growth on Modified Czapekdox medium (MCD). The physical and nutritional conditions were optimized for maximum production of L-asparaginase by F. solani under submerged fermentation conditions (SmF). The fungi exhibited significant variations in the production of L-asparaginase under the influence of incubation period, temperature, pH, carbon and nitrogen sources. It was observed that maximum enzyme activity was recorded on the 6th day of incubation period at pH 7.0 with an incubation temperature of 30°C at 120 rpm. Sucrose (0.2%) was the best carbon source. Different nitrogen sources at concentrations ranging from 0.1% to 0.5% were assessed. Among them, ammonium nitrate (0.4%) and sodium nitrate (0.4%) showed maximum production of L- asparaginase

Induction of Systemic Resistance in Tomato against Ralstonia Solanacearum By Pseudomonas Fluorescens

The biological control agent Pseudomonasfluorescens was used against the bacterial wilt causing Ralstoniasolanacearum. The present investigation focuses on the role of defenserelated enzymes in imparting resistance in tomato against R. solanacearum. A total of ten rhizobacterial isolates werescreened against R. solanacearum, ofwhich three isolates (Pf3, Pf5 & Pf8) showed a maximum inhibition againstthe pathogen and were further identified as P.fluorescens by 16S rRNA analysis. Seedling treatment with P. fluorescens isolates significantlyenhanced the quality of seed germination and seedling vigor. The three P. fluorescens strains were furthertested for their ability to induce the production of defense-related enzymes inplants. Involvement of defense related enzymes in bacterial wilt pathogenesiswas studied in susceptible tomato cultivar (Arka Meghali). Root dip inoculationwas performed with bacterial suspensions of R.solanacearum and P. fluorescens (1× 108 cfu/ml) on ten days old seedlings and harvested at differenttime intervals (0, 3, 6, 9, 12, 15, etc. up to 72 h) and assayed for thedefense related enzyme activity. The seedling treatment of P. fluorescens isolatesinduced a significant increase in the activities of peroxidase (POX), Polyphenoloxidase (PPO), phenylalanine ammonia lyase (PAL), and β-1, 3-glucanase in treated tomato plants and the same trend ofincrease in enzyme activity was observed in P.fluorescens treated tomato seedlings challenged with R. solanacearum. The activities of the enzymes PAL, POX, PPO and β-1, 3-glucanase reached maximum at 24,18, 24 and 24 h after inoculation respectively. Higher accumulation ofphenolics was noticed in plants pre-treated with P. fluorescens and challenge inoculated with R. solanacearum. Native PAGE analysis of both Peroxidase (POX) andPolyphenol oxidase (PPO) was carried out for the time course of enzymeactivities and the isoforms of POX and PPO were examined

Lactic Acid Bacteria Mediated Induction of Defense Enzymes To Enhance the Resistance in Tomato against Ralstonia Solanacearum Causing Bacterial Wilt

The biocontrol agent Lactic acid bacterium (LAB) was used against the bacterial wilt caused by Ralstonia solanacearum. The present investigation focuses on the role of defense related enzymes in imparting resistance to tomato plants against R. solanacearum. The LAB isolate was tested for its ability to induce the production of defense-related enzymes in treated tomato seedlings. Tomato seedlings were raised from LAB pretreated seeds, were challenge inoculated with R. solanacearum, harvested at different time intervals (0–72 h) and assayed for defense enzyme activity. The LAB treated seeds showed increase in germination percentage (6%) and seedling vigour index (259) compared with control. Treatment of tomato seedlings with LAB isolate induced a significant amount of Peroxidase (POX), Polyphenol oxidase (PPO), Phenylalanine ammonialyase (PAL), total phenolics and β-1,3-glucanase activities. The activities of PAL, POX, PPO and β-1,3-glucanase reached maximum at 24 h, 24 h, 32 h and 24 h respectively after challenge inoculation. Increased accumulation of phenolics was noticed in plants pre-treated with LAB. Native PAGE analyses of POX and PPO were carried out for the time course of enzyme activities and the isoforms of POX and PPO were examined. In field study, ten isolates of R. solanacearum treated plots yielded an average of 32.4–50 kg/m2 and LAB treated plots an average of 153.5 kg/m2. As compared to the control, LAB increased the yield by 15.3% (8.2 kg/m2) and the pathogen infected plants and pre-treated with LAB gave an average of 55% (28.3 kg/m2 compared to the infected plots). Field experiment results indicated that LAB exhibited 61.1% of disease reduction of bacterial wilt in tomato

Antimicrobial and Antioxidant Potential of Endophytic Fungi Isolated from Ethnomedicinal Plants of Western Ghats, Karnataka

A total of 79 endophytic fungal isolates were obtained from four wild medicinal plants-Tinospora cordifolia (Willd.) Hook.f and Thomson (Menispermaceae), Piper nigrum L., Piper longum L. (Piperaceae) and Zingiber officinale Roscoe (Zingiberaceae)from Western Ghats of Karnataka and screen them for antimicrobial and antioxidant potential.Among them, 16isolates depicting good antimicrobial activityby agar plug method (2.33mm-20.66mm) and agar well diffusion method (2.66mm-21mm)against human pathogens were identified by molecular techniques andsubjected to secondary metabolite extraction. The extracts were tested for their antioxidant potential by DPPH assay, ABTS assay, reducing power assay and total phenolic content. The isolate ABR4 (Fusarium solani) of Tinospora cordifoliashowed remarkable antimicrobial activity against the human pathogens at tested concentrations of 20-100µg/ml. The isolate GKS (Aspergillus terreus) of Zingiber officinale demonstrated excellent antioxidant activity (IC50-3.34) as compared to standard Gallic acid (IC50 – 5.54) which has not been reported previously. The findings of the study indicate that endophytic isolates serve as a potential source of novel bioactive products

Lactic acid bacteria mediated induction of defense enzymes to enhance the resistance in tomato against Ralstonia solanacearum causing bacterial wilt

The biocontrol agent Lactic acid bacterium (LAB) was used against the bacterial wilt caused by Ralstonia solanacearum. The present investigation focuses on the role of defense related enzymes in imparting resistance to tomato plants against R. solanacearum. The LAB isolate was tested for its ability to induce the production of defense-related enzymes in treated tomato seedlings. Tomato seedlings were raised from LAB pretreated seeds, were challenge inoculated with R. solanacearum, harvested at different time intervals (0–72 h) and assayed for defense enzyme activity. The LAB treated seeds showed increase in germination percentage (6%) and seedling vigour index (259) compared with control. Treatment of tomato seedlings with LAB isolate induced a significant amount of Peroxidase (POX), Polyphenol oxidase (PPO), Phenylalanine ammonialyase (PAL), total phenolics and β-1,3-glucanase activities. The activities of PAL, POX, PPO and β-1,3-glucanase reached maximum at 24 h, 24 h, 32 h and 24 h respectively after challenge inoculation. Increased accumulation of phenolics was noticed in plants pre-treated with LAB. Native PAGE analyses of POX and PPO were carried out for the time course of enzyme activities and the isoforms of POX and PPO were examined. In field study, ten isolates of R. solanacearum treated plots yielded an average of 32.4–50 kg/m2 and LAB treated plots an average of 153.5 kg/m2. As compared to the control, LAB increased the yield by 15.3% (8.2 kg/m2) and the pathogen infected plants and pre-treated with LAB gave an average of 55% (28.3 kg/m2 compared to the infected plots). Field experiment results indicated that LAB exhibited 61.1% of disease reduction of bacterial wilt in tomato

Ameliorated Antibacterial and Antioxidant Properties by Trichoderma harzianum Mediated Green Synthesis of Silver Nanoparticles

Biosynthesis of silver nanoparticles using beneficial Trichoderma harzianum is a simple, eco-friendly and cost-effective route. Secondary metabolites secreted by T. harzianum act as capping and reducing agents that can offer constancy and can contribute to biological activity. The present study aimed to synthesize silver nanoparticles using T. harzianum cell filtrate and investigate different bioactive metabolites based on LC-MS/MS analysis. The synthesized silver nanoparticles (AgNPs) from T. harzianum were characterized by ultraviolet–visible spectrophotometry, Fourier transform infrared spectrometry (FT-IR), energy-dispersive spectroscopy (EDS), dynamic light scattering (DLS), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The surface plasmon resonance of synthesized particles formed a peak centered near 438 nm. The DLS study determined the average size of AgNPs to be 21.49 nm. The average size of AgNPs was measured to be 72 nm by SEM. The cubic crystal structure from XRD analysis confirmed the synthesized particles as silver nanoparticles. The AgNPs exhibited remarkable antioxidant properties, as determined by DPPH and ferric reducing antioxidant power (FRAP) assay. The AgNPs also exhibited broad-spectrum antibacterial activity against two Gram-positive bacteria (S. aureus and B. subtilis) and two Gram-negative bacteria (E. coli and R. solanacearum). The minimum inhibitory concentration (MIC) of AgNPs towards bacterial growth was evaluated. The antibacterial activity of AgNPs was further confirmed by fluorescence microscopy and SEM analysis

Endophytic Fungi—Alternative Sources of Cytotoxic Compounds: A review

Cancer is a major cause of death worldwide, with an increasing number of cases being reported annually. The elevated rate of mortality necessitates a global challenge to explore newer sources of anticancer drugs. Recent advancements in cancer treatment involve the discovery and development of new and improved chemotherapeutics derived from natural or synthetic sources. Natural sources offer the potential of finding new structural classes with unique bioactivities for cancer therapy. Endophytic fungi represent a rich source of bioactive metabolites that can be manipulated to produce desirable novel analogs for chemotherapy. This review offers a current and integrative account of clinically used anticancer drugs such as taxol, podophyllotoxin, camptothecin, and vinca alkaloids in terms of their mechanism of action, isolation from endophytic fungi and their characterization, yield obtained, and fungal strain improvement strategies. It also covers recent literature on endophytic fungal metabolites from terrestrial, mangrove, and marine sources as potential anticancer agents and emphasizes the findings for cytotoxic bioactive compounds tested against specific cancer cell lines