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MENDELNET 2013IN-VITRO ANTIBACTERIAL SENSITIVITY OF USNEA BARBATALICHEN EXTRACTED WITH METHANOL AND ETHYL- ACETATEAGAINST SELECTED STAPHYLOCOCCUS SPECIES FROM BOVINEMILKIdamokoro E. 1 , M., Masika P. 2 , Muchenje V. 1 , Green E. 31 Department of Livestock and Pasture, Faculty of Science and Agriculture, University ofFort Hare, Private Bag X1314, Alice 5700, South Africa2 Agricultural and Rural Development Research Institute, Faculty of Science andAgriculture, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa3 Microbial Pathogenicity and Molecular Epidemiology Research Group, Department ofBiochemistry and Microbiology, Faculty of Science and Agriculture, University of FortHare, Private Bag X1314, Alice 5700, South AfricaE-mail: egreen@ufh.ac.za, easyg@webmail.co.zaABSTRACTOur objective was to evaluate the antimicrobial potential of Usnea barbata lichen as a medicinalplant against selected Staphylococcus species isolated from raw milk of mastitis cows. In-vitroscreening of the methanolic and ethyl-acetate extracts of U. barbata were evaluated to determinetheir antimicrobial activity against thirteen different Staphylococcus species. The selectedorganisms were isolated from raw bovine milk by several biochemical tests and identified with anAPI staph kit (bioMerieux, France). The antimicrobial activity of the extracts were evaluated usingboth the agar well diffusion method and the broth micro-dilution technique to determine the meanzone of inhibition and the minimum inhibitory concentration (MIC), respectively. The minimumbactericidal concentrations (MBC) of the extracts were also evaluated. Both the methanolic andethyl-acetate extract showed variable antimicrobial activity against the Staphylococcus species withmean zones of inhibition ranging from 0 - 34 mm in diameter. Susceptibility by the Staphylococcusspecies tested in the methanol and the ethyl-acetate extract was 92.31% and 53.85% respectively.The MIC result for the methanol extract ranged from 0.0390 to10 mg/ml, while that of the ethylacetateextract ranged from 0.15625 to 5 mg/ml. The MBC’s were in the range of 40 to > 160mg/ml and 80 to > 160 mg/ml for the methanol and the ethyl-acetate extracts, respectively. Resultsfrom this study revealed the in vitro antimicrobial activity of Usnea barbata lichen and thereforevalidate the use of the plant in traditional medicine.Key words: antimicrobial resistance, mastitis, microbial activity, medicinal plantAcknowledgments: The authors wish to thank M the National Research Foundation and GovernMbeki Research Development Centre, University of Fort Hare for funding.203 | P age