Improving the growth response ofBorreliaspecies
Borrelia species are microaerophilic spirochetes, i.e., they are unable to grow in the presence of atomospheric oxygen (21%) or under anaerobic conditions. Compounds that have been shown to quench toxic products of oxygen (i.e., superoxide radicals, hydrogen peroxide, hydroxyl radicals, and singlet oxygen) were added to Borrelia growth media (Kelly's medium). Among the compounds tested were catalase, superoxide dismutase, peroxidase, dithiothreitol (DTT), formate, fumarate, dimethyl sulfoxide (DMSO), manganese, activated charcoal (Norit A), mannitol, and a combination of ferric chloride and potassium (meta)bisulfite (iron-bisulfite). Of these, the compounds that were the most effective in enhancing the growth of the species of Borrelia tested were iron-bisulfite, DTT, and DMSO. DTT possesses the ability to break down hydrogen peroxide, and iron-bisulfite has been reported to have superoxide dismutase-like activity in artificial media. Iron-bisulfite, DMSO, sodium formate, DTT, and combinations of these compounds have been incorporated into solid and biphasic Kelley's medium to determine their effect on microaerobic and aerobic growth on plates and in biphasic medium. Iron-bisulfite was the most effective compound tested under these conditions.Key words: Borrelia, bisulfite, spirochetes, microaerobe.