GREEN SYNTHESIS AND CHARACTERIZATIONS OF SILVER NANOPARTICLES USING FRESH LEAF EXTRACT OF MORINDA CITRIFOLIA AND ITS ANTI-MICROBIAL ACTIVITY STUDIES

Objective: To develop a rapid method of synthesis of silver nanoparticles (Ag NPs) using the fresh aqueous leaf extract of Morinda Citrifolia from 0.1 M AgNO3 solution, to characterize the resulting Ag NPs and also compare their antimicrobial activity with those of standard drugs against human pathogenic bacteria.Methods: 25 ml of the aqueous extract was added to 25 ml of 0.1 M aqueous AgNO3 at room temperature. The mixture was stirred continuously for 5-10 minutes. The reduction was completed with the appearance of brownish-black colored dispersion. The resulting nanoparticles were characterized using UV-Vis absorption spectra and Particle size analysis (DLS method). Further the Antimicrobial activity was compared with the drugs against S. aureus and P. aureginosa strains using the disk diffusion method.Results: The formation of Silver nanoparticles was confirmed with the help of UV-Vis absorption spectra at ≈ 425 nm and particle size as approximately 100 nm using Particle size analysis (DLS method). The anti-microbial activity of the Ag NPs so synthesized was studied against human pathogens in wound infections such as S. aureus and P. aureginosa strains. The inhibitory activity for Ag NPs was compared with those of known drugs such as tetracycline, Ceftazidime and Amikacin at 30 mcg. The inhibitory activity of the Synthesized Ag NPs was found pronounced against P. aureginosa strains.Conclusion: A rapid method of synthesizing Ag NPs has been developed by using the fresh leaf extract of Morinda Citrifolia and it was found that the extract is a potential reducing agent to produce stable Ag NPs. The research provides a new input to the development of anti-microbial agent.Â

Grapevine adaptation to abiotic stress: an overview

International audienc

Effects of stress and defence allocation on tree growth: Simulation results at the individual and stand level.

The long life span of trees implies that they are more or less frequently confronted with different biotic and abiotic stress situations during their lives. However, biotic stress such as attacks by herbivores or pathogens and abiotic stress such as frost or drought could strongly vary in frequency, intensity, duration, time of occurrence as well as in the involved tissues. This urged trees to develop flexible defence mechanisms during their evolution ensuring a high probability of survival to regenerate successfully. Based on an analysis of existing literature on plant response to herbivory, McNaughton (1983) concludes that “. . .the yield of the tissue affected and other tissues is not affected in proportion to the amount of tissues damaged by the herbivore”, referring also to Lee and Bazzaz (1980) and Neilsen (1981). McNaughton presents a set of alternative patterns about the eff

A conceptual model for the development of Phytophthora disease in Quercus robur

Here, a conceptual model is presented for the development of Phytophthora disease in pedunculate oak. The model is presented using the causal loop diagram tool and gives an overview of how various abiotic and biotic factors, such as soil moisture, nutrient availability and mycorrhizal colonization, may affect the reproduction and the infective capacity of soil-borne Phytophthora species, the susceptibility of the host and subsequent disease development. It is suggested that the link between the root damage caused by Phytophthora species and overall tree vitality is in the assimilation and allocation of carbon within the plants. The potential impact of environmental factors on these processes is discussed. The model is presented with reference to scenarios related to variation in soil moisture and nutrient availability. The need for species-specific validation of the model and the implications of the model are discussed