: In the present study, the key industrial strain of Kluyveromyces lactis NRRL Y-110 was used todevelop an industrial process for probiotic cell mass production. Therefore, the biomass production process of K. lactis was developed via the optimization of different medium and process parameters in shake flask and bioreactor levels. In the first part of the work, the effect of medium composition on the production of biomass was investigated in shake flask culture.