The present invention relates to a liquid composition of live Mollicutes bacteria and a stabiliser, whereby the stabiliser is a natural deep-eutectic solvent (NADES). In this liquid composition the live Mollicutes are stabilised without need for freezing or freeze-drying. This allows various advantageous uses in diagnostics and medicine, specifically as a liquid vaccine for use against infection or disease caused by Mollicutes bacteria, for human- or non-human animals.