BIOMYC-1 is a solution based on the antibiotic tiamutin which is produced by the fungus Pleurotus mutilus.This antibiotic has been shown to be very effective in eliminating the mycoplasma species frequently present in contaminated cell cultures and is generally used sequentially in combination. with minocycline (see BIOMYC-2). Following our protocol, the mycoplasmas do not develop resistance to thess antibiotics – a common occurrence with other antibiotic treatment methods. The treatment is based on alternating use of the two antibiotics: four days with tiamutin followed by three days with minocycline, and repeating the cycle 2-3 times. On completion of the treatment, the cells should be grown on media without antibiotics for at least two weeks and then re-tested for the presence of mycoplasmas. If the culture test is positive, the course of treatment should be repeated.