Evaluation of antibacterial potencies of eight lichen extracts against gram-positive moderately halophilic bacteria

Abstract

The leather sector has global economic importance. Overcoming microbiological problems, especially arising from halophilic bacteria, will greatly reduce product losses. In this study, lichen species including Usnea sp., Platismatia glauca, Ramalina farinacea, Evernia divaricata, Bryoria capillaris, Hypogymnia tubulosa, Pseudevernia furfuracea and Lobaria pulmonaria were examined for their antibacterial efficacies against Staphylococcus saprophyticus subsp. saprophyticus (TR5) and Salinicoccus roseus (KV3) which are proteolytic and lipolytic Gram-positive moderately halophilic bacteria. The extracts of P. glauca, B. capillaris, P. furfuracea and L. pulmonaria had no antibacterial efficacy against the test bacteria. On the other hand, the extracts of H. tubulosa, R. farinacea, Usnea sp. and E. divaricata had considerable antibacterial effect with varying percentages of inhibition. The maximum inhibition ratios at the tested concentrations of 15–240 µg ml–1 for lichen samples of H. tubulosa, R. farinacea, Usnea sp. and E. divaricata were detected as 94.72 ± 0.75%, 76.10 ± 1.85%, 99.36 ± 0.04%, 89.49 ± 2.26% for TR5 and 97.44 ± 0.14%, 95.92 ± 0.29%, 97.97 ± 0.39%, 97.58 ± 0.53% for KV3, respectively. The most remarkable suppression was obtained with Usnea sp. extracts against KV3. These results indicate the need for further studies investigating the applicability of these natural resources to control moderately halophilic bacteria in the preservation of raw hides and skins.