EXPLORATION OF AVERRHOA CARAMBOLA EXTRACT AS AN E. COLI BIOFILM MODULATING AGENT

Rimi Singha, Paramadatta Das, Gourab Debnath, Mousumi Goswami, Abhijit Bhattacharya4, Shukdeb Acharjee*, Manash C. Das*

ABSTRACT

Escherichia coliis a gram-negative bacillus associated with intestinal illness in humans. E. coli biofilm consists of a bacterial colony embedded in a matrix of extracellular polymeric substances (EPS), which protects the microbes from adverse environmental conditions and results in infection. Biofilm physiology is characterized by increased tolerance to stress, antibiotics, and host immunological defence. Averrhoa carambolaL., commonly known as carambola or star fruit, is a perennial tree in the family Oxalidaceae. It contains oxalic acid and caramboxin. It is a rich source of minerals and vitamins, including magnesium, potassium, and vitamin C. In this study, the antibacterial properties of Averrhoa carambola fruit water extract (AW) and Averrhoa carambola ethanolic extract (AE) against E. coli were evaluated, and their effects on biofilm formation and dispersion were determined. The broth microdilution method was used to determine the minimum inhibitory concentration (MIC) at concentrations rangingfrom 1 µl/ml to 25 µl/ml, and absorbance was measured at 600 nm. An agar diffusion assay was performed to determine the zone of inhibition for AW and AE, with the zones7.97mm and 9.21mm,respectively, observed at 6 µl/ml and 13 µl/ml concentrations in comparison with the antibiotic gentamicin. Biofilm dispersion assay was performed, and before and after staining, the optical density was recorded. Both AW and AE extracts have exhibited a zone of inhibition against E. coli, and optical density measurements indicated inhibition of bacterial growth at 75 µg/ml. Biofilm dispersion assay values recorded before and after staining demonstrated antibiofilm activity. The findings indicate that AW and AE extracts possess antibacterial activity and inhibit E. coli biofilm formation.

Keywords: Averrhoa carambola, Extract, Biofilm, Exopolysaccharide, MIC, AW, AE.