Abstract: The present invention relates to methods of activating live lactic acid bacteria comprising exposing said bacteria to a preparation comprising citrate, wherein said bacteria have the ability to utilize citrate as an external electron acceptor. The present invention further relates to methods to enhance the activity of certain live bacteria in mammals. More specifically the invention relates to improve the wake-up of certain lactic acid bacteria from the freeze-dried state. The present invention also relates to preparations comprising said activated bacteria and therapeutic uses of said activated bacteria.