Comparative Analysis of the Antibacterial Activity of Sri Lankan Black Tea from Different Geographical Areas

Abstract

Tea is one of the most ancient and popular therapeutic beverages consumed by people all over the world. It is made from the leaves and buds of the plant “Camellia sinensis”. Tea is cultivated in more than thirty countries around the world as a plantation crop. In the present study, tea infusions from twenty black tea samples belonging to low (Dust (I), BOPF, BOPI, OPI, Pekoe), mid (Dust (I), Dust, BOPF Local, BOPI, BOP, OPI, Pekoe) and up (Dust, BOPF, BOP, FBOP, FBOPI, OPA, OPI, Pekoe) country of Sri Lanka were tested by microdilution assay for antibacterial activities against Escherichia coli, Methicillin-resistant S. aureus (MRSA) and M. smegmatis (MS). The results were statistically analyzed using ANOVA. None of the tea infusions showed antibacterial activity against gram-negative bacterium E. coli even at the highest concentration of tea infusion. All the tea samples had antibacterial activity against gram-positive bacteria M. smegmatis and S. aureus. S. aureus was more sensitive to all the tested tea samples than M. smegmatis. Samples with the highest and the lowest antibacterial activity against M. smegmatis were: low-country Dust (I) (MIC- 1.24 mg/ml) and mid-country BOPF (MIC- 2.78 mg/ml) respectively, while the highest and the lowest antibacterial activity against S. aureus were; mid-country BOP (MIC- 0.38 mg/ml) and low-country BOPF (MIC- 1.72 mg/ml) respectively. Agro-climatic elevation of the tea sample affected antibacterial activity of black tea. Based on the results of this study, it is concluded that Sri Lankan black tea possesses selective antibacterial activity against Gram-positive bacterial species and Sri Lankan black tea may have the potential to be used as a safe supplementary beverage during antibacterial therapy.