Epigallocatechin gallate (EGCG) is the main component of green tea extracts that inhibits the growth of Mycobacterial smegmatis mc(2)155, and the mechanism is not clear. This study showed the effects of EGCG on the growth of mc(2)155. The content and the structure of EGCG in LB medium with mc(2)155 were identified by HPLC and LC/MS. Transmission electron microscopy was utilised to identify the cell envelope structure. As a result, the optional inhibition concentration was determined to be 20 μg mL(-1). Most of EGCG was transferred into its isomeride in LB medium, but the inhibition effects against mc(2)155 had yet been maintained. The changes of cell envelope structure were showed after EGCG treatment for 18 h. The cell wall appeared to have a less electron-translucent zone, turn rougher and thicker. The results show that EGCG impacts the integrity of mycobacterial cell wall and is likely be a better prophylactic agent against tuberculosis.
Keywords: M. smegmatis mc2155; antimicrobial effect; cell-wall structure; epigallocatechin gallate.