Antibacterial activity in extracts of some bryophytes from China and Mongolia

Disc diffusion assay was used to screen for antibacterial activity of ethanolic extracts of 60 bryophytes belonging to 39 genera, including 38 liverworts, one, hornwort, and 21 mosses from China and Mongolia. Out of 60 bryophytes, 56 species (93.3%), including all liverworts tested, have detectable antibacterial activity against at least two of the selected seven bacteria, including four Gram positive (Bacillus megaterium, Bacillus subtilis, Bacillus thuringiensis, and Staphylococcus aureus) and three Gram negative (Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas putida). Seventeen species (two mosses and 15 liverworts) are active against all seven selected bacterial species. Out of 21 mosses, four species did not show positive evidence. Antibacterial activity was particularly prominent in the members of Conocephalum, Frullania, Herbertus, Marchantia, Mastigophora, and Porella. The antibacterial activity of the alcoholic extracts of Bazzania tridens, Herbertus aduncus, Porella densifolia, Polytrichum commune, and Thuidium kanedae, expressed as MICs (minimal inhibitory concentration) and MBCs (minimal bactericidal concentration), were compared with three reference antibiotic drugs. Out of the seven bacteria tested, Staphylococcus aureus is most resistant to the extracts of both liverworts and mosses. Pseudomonas putida is most sensitive to the extracts of mosses, and Bacillus subtilis is most sensitive to the extract of liverworts. The broad spectrum of antibacterial activity shown in the present study suggests that most liverworts are worthy of further investigation for the nature of their definitive antibacterial compounds and other potentially biologically active ingredients. The investigation of oil bodies of the tested liverworts reveals that there is no correlation between the antibacterial activity and the size and numbers of oil bodies.