Antibacterial and antioxidant capacity of polar microorganisms isolated from Arctic lichen Ochrolechia sp

Although many scientists have been studying lichens, the bacterial communities among lichens have not been fully explored. In this study, the biological activities of bacterial isolates from Arctic lichen Ochrolechia sp. were screened. Cell cultures were extracted using ethyl acetate, and these cultures were tested for antibacterial and antioxidant activities. To evaluate the antibacterial activities, we carried out a disk diffusion test and minimum inhibitory concentration assay. The inhibition zone diameter (mm) was 8 to 12, and its MIC value ranged from 222.0 to > 1000 μg/ml (control antibiotic ampicillin ranged from 0.31 to 0.58 μg/ml). PAMC26625 (Sphingomonas sp., sequence similarity: 99.108%) showed a high amount of total phenolic and total flavonoid contents within 5 extracts and also exhibited 77.23% and 80.02% in the 1,1-diphenyl-2-picryl-hydrazyl assay and the 2,2'-azino-bis(3-ethyl benzothiazoline-6-sulphonic acid) assay, respectively. In the ferric reducing antioxidant power assay, it was determined that PAMC26625 contained a higher amount of ferrous ion [8.72 mM Fe(II)/mg extract] than control ascorbic acid [6.21 mM Fe(II)/mg extract]. Our data indicated that they had potential to be novel sources of antibacterials and antioxidants.