Antibacterial and Antibiofilm Activity of Silver Nanoparticles Synthesised by Beetroot Containing Betalains Pigment on Clinical Bacterial Isolates

Abstract

Introduction: Artificial colours have been used in foods for many years with adverse side-effects. As a result, many studies have focused on natural dyes, and interest in natural dyes is increasing every day due to the lack of side-effects. The betalains are pigments, which are present in the Beta vulgaris L (red beet) roots; these are exploited for native colouring and additive agents in food. These compounds possess many desirable properties such as antioxidant and antimicrobial activity etc., Nanotechnology is currently being used to enhance plant medicinal applications. It is an environmentally non toxic and low cost method. Aim: To examine the role of beetroot containing betalain on synthesising Silver Nanoparticles (AgNPs) and to determine the antibacterial activity. Materials and Methods: This in-vitro study was carried out in Department of Botany, KK College in Namakkal, Tamil Nadu during the period of December 2018 to December 2020. The 2mM of AgNPs was utilised for the preparation of nanoparticles with beetroot containing betalains. The characterisation of synthesised AgNPs was done by Fourier Transform Infrared spectroscopy (FTIR), Ultraviolet-Visible (UV-Vis) spectroscopy, Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). In addition, the antibacterial activity of AgNPs were evaluated by the agar well-diffusion method. Results: In this study, the highest concentration of betalains observed at pH 5 in both solvents [ethanol (154.4 mg/100 mg) and water (131.2±0.15/100 mg)] was recorded. The acetone recorded a maximum of 143.8 mg/100 mg at pH 4. Bio sourced AgNPs had antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Enterococcus faecalis, Pseudomonas aeruginosa, Proteus sp, Salmonella sp and Acinetobacter baumannii. Furthermore, synthesised AgNPs inhibited the biofilm formation in all isolates. Conclusion: This study reveals that AgNPs exhibit strong antimicrobial activity so that they can be developed as new types of antimicrobial agents to treat bacterial infections, including biofilm bacterial infections, and are attractive and environmentally friendly.

Keywords

• additives
• antibacterial
• microscopy
• nanotechnology
• natural pigment