10.22376/ijpbs.2019.10.1.p1-12 Volume 2 Issue 4 2011 (October - December) Antibacterial activity of acetone, methanol and aqueous extract prepared from some lichen  lessThan br / greaterThan species were evaluated against five bacterial strains viz. Staphylococcus aureus, Escherichia lessThan br / greaterThan coli, Vibrio cholerae, Shigella dysenteriae. Shigella flexneri The aqueous, methanol and acetone  lessThan br / greaterThan extracts exhibited a variable range of antibacterial activity to bacterial strains. The acetone and  lessThan br / greaterThan methanol extracts of all investigated lichens showed selective antibacterial activity. The lessThan br / greaterThan methanol extracts were usually the most active against test organisms. An aqueous extracts of  lessThan br / greaterThan investigated lichens were found to be inactive against all tested bacteria.  Sankar Narayan Sinha And Mrinal Biswas lichen, antibacterial activity, Staphylococcus aureus, Escherichia coli, Vibrio cholerae, Shigella dysenteriae. Shigella flexneri 23-28