INFLUENCE OF PHYSICO-CHEMICAL PARAMETERS ON SECONDARY METABOLITE PRODUCTION BY MARINE FUNGI

Objective: Our study aimed to characterize and optimize the physico-chemical properties which render the high yield of bioactive secondary metabolites from marine fungi and its antibacterial activity against clinical pathogens.Methods: Bioactive secondary metabolites extracted from marine fungi of Nijampatnam mangroves, Guntur district Andhra Pradesh, India. By using different solvent systems, secondary metabolite was screened for antimicrobial activity against clinical pathogen, Optimization of cultural conditions for maximizing the yield of biomass and compared the yield in different broth media and minimum inhibitory concentration of the optimised compound done for both compounds.Results: fungal extracts GAPS-1 and GAPS-2 was affectively extracted in ethyl acetate. Isolated compound showed antibacterial activity highest zone of inhibition against E. coli and least to Pseudomonas. Maximum yield of the compound was achieved in modified potato dextrose broth (PDB) medium containing 20% w/v Potato 2% w/v Dextrose broth containing1% w/v glucose and sucrose,1% w/v beef extract and ammonium chloride and 0.01 % mineral salts(MGSO4 and MNSO4) at 25 °C and 30 °C and pH 7.0 and 8.0 with 144 h of incubation period. The yield was observed maximum in potato dextrose broth compared to czapek dox broth, sabaraud's broth and nutrient broth and minimum inhibitory concentration of the optimized compound ranges from 250 μg for gaps-1 and 300 μg for gaps-2.Conclusion: Secondary metabolite yield maximum in potato dextrose broth and its potential anti-bacterial activity needs further investigation for pharmaceutical applications

Biosynthesis and characterization of Dillenia indica-mediated silver nanoparticles and their biological activity

Dillenia indica L. is a traditional medicinal plant well known for its ability to cure various human diseases. In the current study, silver nanoparticles have been synthesized by simple and eco-friendly method using Dillenia indica extract. The green synthesized nanoparticles were characterized by Fourier transform infrared (FTIR), UV-visible spectroscopy, Atomic force microscopy (AFM), High-resolution transmission electron microscopy (HR-TEM), Zeta Potential and Size Distribution. UV-visible and FTIR spectra, AFM, HR-TEM and Zeta Potential readings and size distribution conformed that the synthesized silver particles were in the size of nano. The green synthesized silver nanoparticles were subjected for antibacterial activity against Gram-positive bacteria Enterococcus faecalis and Gram-negative bacteria Escherichia coli by agar well diffusion method. The synthesized AgNPs exhibited significant inhibition of 27 and 16 mm against the test bacteria at 0.25 mg/ml. Further the antibacterial activity was confirmed by live and dead cell assay by fluorescence microscopy and morphological changes of bacteria were studied by Scanning electron microscope (SEM). The study recommends that the synthesized silver nanoparticles using Dillenia indica extract have potential application in inhibition of bacteria owing to their potent antibacterial activity