Effects of Tea and Fruits Juice on Bacterial Proliferation

Abstract

Effect of tea and fruits on the proliferation of opportunistic pathogens were examined. Three kind of teas: green tea, oolong tea and black tea and four pathogens: Bacillus subtilis, Staphylococctus aureus, E. coli and Pseudomonas aeruginosa were subjected to the experiments. The three kinds of tea leaf extracts (25g leaves in 500ml at 95C for 5min) inhibited the proliferation of S. aureus, B. subtilis and E. coli, but'not of P. aerugz'nosa, The effectiveness was correlated with the catechin content of the teas and MIC of catechin against S. aureus was lmg/ml, against B. subtilis and E. coli were 1-2mg/ml. The effect was bactericidal and the three bacterial strains tested were all killed at the concentration of above MIC, but P. aeruginosa was resistant. Juice of lemon and citrus (Sudachi), inhibited the proliferation of all the four organisms within 60min soaking, but those of grapefruit, kiwi and apple were less effective in inhibiting the proliferation. The effect was bactericidal and the results suggest the major factor was the lower pH.