地衣抗生物質之初步研究—地衣丙酮抽出物對細菌的影響

Abstract

Seven species of lichens were collected from the northern mountainous areas of Taiwan. Lichen substances were extracted by acetone. Six of the 7 lichens acetone extracts have inhibitory effect on Gram positive bacteria including both cocci and bacilli. Usnea longissima has an inhibitory effect on several species of both Gram positive and Gram negative bacteria and also on yeast. Its range of inhibition on bacteria is very wide, and its inhibition on bacteria is species specific. The Usnea longissima acetone extract is highly stable to acid, alkaki and heat. The lowest effective inhibitory concentration of this acetone extract is different depending on the bacteria treated. The lowest effective inhibitory concentration of this acetone extracted substance is 100 ppm for the bacterium most sensitive to this extract among the various bacteria tested. When bacteria are treated with this lichen extract at less than the lowest effective inhibitory concentration, the percent of viable bacteria are decreased. Bacteria treated with the Usnea longissima acetone extract, and then diluted appropriately to eliminate further action of the acetone extract showed that these bacteria did not recover their viability. This indicates that the acetone extract for these bacteria is bactericidal rather than bacteriostatic. The protein and carbohydrate content of these bacteria are decreased by the treatment of Usnea longissima acetone extract.