SCREENING AND IDENTIFICATION OF HEAVY METAL-TOLERANT ENDOPHYTIC FUNGI LASIODIPLODIA THEOBROMAE FROM BOSWELLIA OVALIFOLIOLATA AN ENDEMIC PLANT OF TIRUMALA HILLS

ABSTRACTAim: The aim of this study was to evaluate the heavy metal resistance potentiality of endophytic fungi isolated from the leaves of Boswellia ovalifoliolata,an endemic medicinal plant of Tirumala Hills.Methods: Initially, isolation of fungal endophytes was carried out. Isolated fungi were screened for the heavy metal resistance against Co, Cd, Cuand Zn using growth and evaluated their maximum tolerant capacity. Molecular identification of endophytic fungi was carried out by 18S rRNA geneamplification and Sanger's nucleotide sequencing. Phylogenetic tree was constructed using NCBI Clustal W.Results: Ten different endophytic fungi were isolated from the leaves of B. ovalifoliolata. Among the isolated endophytic fungi, five showed resistanceto Co, Cd, Cu, and Zn. The most resistant fungus was identified as Lasiodiplodia theobromae based on 18S rRNA gene sequencing.Conclusions: L. theobromae was isolated from B. ovalifoliolata and identified as one of the useful fungi involved in mycoremediation against heavymetal toxicity.Keywords: Heavy metals, Endophytic fungi, Endemic plant, Bioremediation

Comparative Studies on Growth and Remediation of Waste Water by Two Cyanobacterial Biofertilizers

Nitrogen fixing cyanobacteria are ecologically significant inputs in improving the plant productivity in tropical countries like India. Large scale cultivation of these organisms using inorganic media is relatively expensive. In the present study utilization of kitchen waste water emerged from a pilgrim centre as a source of nutrients and its remediation was compared using two blue green algal cultures viz. Anabeana variabilis and Nostoc muscorum. A complete randomized design was created for the experiment that was performed on BG-11, 100% and 75% KW (Kitchen Water) media. The physicochemical properties of waste water were analyzed before and after cultivation. It was found that the N. muscorum was more effective in removal of phosphorous and nitrogen contaminants from waste water to meet the standards of safe discharge besides producing more biomass compared to A. variabilis

TRITERPENOID SAPONINS: A REVIEW ON BIOSYNTHESIS, APPLICATIONS AND MECHANISM OF THEIR ACTION

Saponins are the potential bioactive compounds secreted by plants, endophytic fungi and marine organisms. Saponins are the glycosides containing non sugar portion, aglycone (sapogenin) attached to sugar moiety by glycosidic linkage. Depending on the chemical nature of aglycone, saponins are of triterpenoid and steroid saponins. The present review gives an overview of the biosynthesis pathway of triterpenoid saponins and mechanism of the biosynthesis. The review discusses the biomedical and pharmaceutical importance of triterpenoid saponins as they possess different activities including antimicrobial, haemolytic, hypolipidemic, immunomodulating and cytotoxic activities. The review also focuses on the mechanism of their action towards various activities.Â

RAPID SYNTHESIS OF SILVER NANOPARTICLES USING AQUEOUS LEAF EXTRACT OF ACHYRANTHES ASPERA AND STUDY OF THEIR ANTIMICROBIAL AND FREE RADICAL SCAVENGING ACTIVITIES

Objective: To study the biosynthesis of silver nanoparticles (AgNPs) using the aqueous leaf extract of Achyranthes aspera and check the antimicrobial and free radical scavenging activity of the biosynthesized AgNPsMethods: 20 ml of aqueous leaf extract of A. aspera was added to 80 ml of 2 mM silver nitrate and the reaction solution was heated at 55-60 °C for 20 min and incubated. Biosynthesized AgNPs were characterized by different spectroscopic measurements including UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction pattern (XRD), Transmission electron microscopy (TEM) and Dynamic light scattering (DLS). Antimicrobial activity of AgNPs was checked against Staphylococcus aureus, Bacillus subtilis (Gram+ve bacteria), Klebsiella pneumonia, Pseudomonas aeruginosa (Gram-ve bacteria), Aspergillus niger, Candida albicans and Candida nonalbicans (Human pathogenic fungi) by employing disc diffusion method. The free radical scavenging activity of AgNPs was checked against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Hydrogen peroxide (H2O2) radicals. Results: After 1 h of incubation, the light yellow color of the reaction solution was turned to dark brown. UV-Vis spectra showed the absorption peak at 445 nm and confirmed the synthesis of AgNPs. FTIR spectra revealed the functional groups plausibly involved in the biosynthesis and stabilization of AgNPs. XRD pattern revealed that the synthesized AgNPs were crystalline in nature with face-centered cubic (FCC) phase. TEM revealed that the synthesized AgNPs were spherical in shape with 20-40 nm in size. DLS analysis revealed that the average size of AgNPs was 24.5 nm. Biosynthesized AgNPs were highly stable due to their high negative zeta potential value of-28.1 mV. AgNPs showed effective antimicrobial activity against S. aureus (16.4 mm), B. subtilis (14.5 mm), K. pneumonia (13.2 mm), P. aeruginosa (12.4 mm), A. niger (12.2 mm), C. albicans (11.5 mm) and C. nonalbicans (11.8 mm). AgNPs showed effective free radical scavenging activity with IC50 values of 77.73 and 90.53 µg/ml respectively against DPPH and H2O2 radicals.Conclusion: Successful and rapid synthesis of AgNPs was achieved using aqueous leaf extract of A. aspera. Biosynthesized AgNPs were proved to be excellent antimicrobial agents and free radical scavengers.Keywords: Achyranthes aspera, Silver nanoparticles, TEM, DLS, Antimicrobial and Radical scavenging activit

BIOFABRICATION OF SILVER NANOPARTICLES USING AQUEOUS LEAF EXTRACT OF MELIA DUBIA, CHARACTERIZATION AND ANTIFUNGAL ACTIVITY

Objective: To investigate the bio-fabrication of silver nanoparticles (AgNPs) using aqueous leaf extract of Melia dubia (ALM) and test the antifungal activity of AgNPs against pathogenic fungi Aspergillus niger and Candida tropicalis. Methods: 10 ml of aqueous leaf extract of Melia dubia was added to 90 ml of 1 mM silver nitrate and incubated for 8h at room temperature. After incubation, the color change was observed from light yellow to dark brown. The synthesized AgNPs were characterized using UV-Vis spectroscopy, Fourier Transform Infra red spectroscopy (FTIR), Energy Dispersive X-ray Spectroscopy (EDX), Scanning Electron microscopy (SEM), X-ray diffraction analysis (XRD) and Atomic Force Microscopy (AFM). Antifungal activity against Aspergillus niger and Candida tropicalis was carried out by employing the disc diffusion method. Results: UV-Vis spectra confirmed the synthesis of AgNPs by showing characteristic peak between 380-450 nm*. FTIR spectra showed the functional groups possibly involved in the synthesis of AgNPs. EDX confirms the presence of elemental silver at 3 Kev. SEM and AFM showed the synthesized AgNPs were spherical in shape with size ranging between 20-40 nm*. XRD analysis revealed the crystalline nature of AgNPs with face centred cubic (FCC) lattice. AgNPs was found to be very effective against the tested pathogenic fungi A. niger and C. tropicalis and formed the inhibition zones 13.0 and 14.5 mm respectively. Conclusion: It is concluded that the bio-fabrication of AgNPs using aqueous leaf extract of Melia dubia was robust and rapid. The AgNPs were stable and proved to be excellent antifungal agents

ENDOPHYTIC FUNGAL ASSISTED SYNTHESIS OF SILVER NANOPARTICLES, CHARACTERIZATION AND ANTIMICROBIAL ACTIVITY

Objective: The objective was to investigate the biosynthesis of silver nanoparticles (SNPs) using extracellular fungal filtrate of Aspergillus niger andcheck their antimicrobial activity against Staphylococcus aureus and Escherichia coli.Methods: 10 ml of extracellular fungal filtrate of A. niger was added to 50 ml of 1 mM silver nitrate and incubated at room temperature for 24 hrs.SNPs were characterized using ultraviolet-visible (UV-Vis) spectroscopy, Fourier transforms infrared spectroscopy (FTIR), transmission electronmicroscopy (TEM), atomic force microscopy (AFM), and X-ray diffraction analysis (XRD). Antimicrobial activity was checked against S. aureus andE. coli by employing disc diffusion method.Results: The color change of the solution from light yellow to dark brown indicated the formation of SNPs. The formation of SNPs was furtherconfirmed by UV-Vis spectroscopy, which showed the characteristic peak between 400 and 460 nm. TEM and AFM analysis showed that the size ofSNPs were between 10 and 50 nm with roughly spherical in shape. XRD analysis confirmed the crystalline nature of SNPs synthesized by showing theBraggs peaks which could be indexed to (111) and (220) of face cubic crystal phase of silver. FTIR showed the peaks at 1026, 1215, 1348, 1632, and2928/cm, which were responsible for the different functional groups possibly involved in the synthesis and stabilization of SNPs. The SNPs formedthe inhibition zones of 14.0 and 12.5 mm against S. aureus and E. coli, respectively.Conclusion: It is concluded that the biosynthesis of SNPs using extracellular fungal filtrate of A. niger was simple, eco-friendly, and robust. The SNPssynthesized were well-dispersed, crystalline in nature and also proved to be excellent antimicrobial agents.Keywords: Silver nanoparticles, Aspergillus niger, Transmission electron microscopy, X-ray diffraction, Antimicrobial activity

Antimicrobial and anti oxidant activities of an Endophytic fungi Isolated from an endemic medicinal plant Pterocarpus santalinus

Endophytic fungi are intriguing microorganisms live inside the healthy plant tissues.   they are quite diverse in nature and have enormous potential for production of important secondary metabolites of biomedical, pharmaceutical and clinical importance. In the present work we have isolated an endophytic fungi from the leaves of Pterocarpus santalinus an endemic medicinal plant of Eastern ghats, Tirumala hills, India. Based on the molecular characterization by 18S rRNA analysis the fungi was identified as Xylaria spp. ENT2 (Accession No. KF493856.1). the crude extract of Xylaria sp. was evaluated for antioxidant and antimicrobial activities. Among the other extracts tested methanolic extract showed highest activity against all the bacterial and fungal pathogens with a minimum bactericidal concentration (MBC) of about 30μg/mL against Staphylococcus aureus and a Minimum Fungicidal Concentration (MFC) of about 50μg/mL against Candida albicans. Similarly methanolic extract proved to be potential natural antioxidant with 56.26±0.08 radical scavenging activity (RSA)

Isolation, screening of rhizosphere fungi antagonistic to rice stem rot disease pathogen Sclerotium oryzae catt.,

Objective: The production of antifungal substances by rhizosphere fungi has long been recognized and this knowledge is entering practical lifethrough the use of fungal antagonists to protect crops against their fungal pathogens.Methods: In this study rhizosphere fungi isolation in serial dilution plate technique, and their antimicrobial properties against plant pathogen testedby dual culture, disc diffusion method. Effect of these fungi in seed germination and growth promoting activity was measured in pot culture method. Results and conclusion: Rhizosphere fungi it has become clear that in addition to diffusible substances evidence has accumulated that these bioactivecompounds are not only able to promote seed germination and plant growth, but also to strongly inhibit pathogenic fungal growth. As the demandfor organic products and the need to render agriculture more sustainable are rising, finding new environmentally friendly crop protection strategiesis essential. In this perspective, the newly discovered capacity of fungal bioactive compounds to efficiently repel phytopathogenic fungi in laboratoryexperiments holds great promise.Keywords: Rhizosphere, Biological control, Sclerotium oryzae, Seed germination