Effect of Green Tea and EGCG on the Growth Rate and Cell Density of the Probiotic Bacteria Lactobacillus acidophilus and Lactobacillus gasseri

Green tea and probiotic bacteria have been reported to have beneficial health effects individually. The purpose of this study was to determine if green tea (GT) or epigallocatechin-3-gallate (EGCG), the main flavonoid component of GT, would stimulate the growth rate and increase the cell density in planktonic cultures of the probiotic bacterial strains Lactobacillus acidophilus NCFM (L. acid.) and Lactobacillus gasseri ATCC 33323 (L. gas.). Aqueous GT and EGCG extracts were prepared and matched for total phenol content. Growth rate was determined using a 96-well microtiter plate assay. Cell density was assessed via optical density at 600nm. GT (1, 2, 10, 20, 30 and 40%) and EGCG (1, 2 and 10%) enhanced the maximum specific growth rate (MSGR) of L. acid. vs. the control. GT (4, 10, 20, 30, and 40%) and EGCG (1, 2, 4, 10, and 20%) also enhanced the MSGR of L. gas. relative to the control. GT (10 and 30%) and EGCG (1% only) increased the cell density of both L. acid. and L. gas. relative to the control. In summary, in preliminary results, GT and EGCG increased the growth rate and final cell densities of both L. acid. and L. gas., suggesting that combinations of probiotic cultures with tea components may promote survival, growth or activity in the gastrointestinal tract. This project was supported by North Carolina State University, the NC Dairy Foundation, and the Southeast Dairy Foods Research Center.