The milk-based medium contains optimal amount of substances which allows maintaining viability and preserving biotechnological properties of lactic acid bacteria cells. This proven fact determines the need of researches for optimization or modification of culture and protective media. Experiments have been carried out to modify culture medium for lactic acid bacteria isolated from goat milk, which will allow the intensive biomass accumulation and the obtaining of a high viable count of microorganisms. The growth dynamics, pH, titratable acidity and the number of viable microorganisms were monitored in cow milk –based medium and in the modified medium – goat milk based. Cultivation of strains was performed at optimal parameters in sterilized hydrolyzed cow and goat milk media for 24 h at 30±2 °C. The dilution method was used to estimate the number of viable lactic acid bacteria cells. Studied strains, specially the strain Lactococcus lactis CNMN-LB-75, showed significant differences during cultivation on the control medium and the modified one, it has been established that the composition of the modified culture medium allows obtaining the highest productivity of autohtonous lactic acid bacteria isolated from goat milk. The highest accumulation of L. lactis CNMN-LB-75 biomass (1,4 mg / ml) was registered after 12 hours of incubation, at the value of pH = 4,5. The maximum count of cells was 3,8 × 1010 at the stationary phase (Fig. 1). The growth parameters was determined by growth rate m= 0,186 oră-1 and the shortest generation time g = 3,725 hours. The protective medium plays an important role in maintaining of the viability of microorganisms during freeze-drying. The base of protective medium for preserving lactic acid bacteria was optimized by substitution of cow milk to goat milk. The mechanism for optimizing protection medium was established by developing mathematical model for calculating the viability index of bacteria considering all possible interactions between milk and phosphate buffer solution (sodium citrate) with the addition of protective substances. The impact of protective cow milk-based and goat milk-based media on strains viability were studied after freeze-drying. In the result of processing the experimental data, was obtained the regression equation which describes in natural values (p <0.05) the changes of lactic acid bacteria strains viability depending on the content of base protective components in the protective medium: Y=-194,12+6,60×L+0,40×C-0,04×L2-0,05C2 where Y is viability of LAB (%), L is goat milk content (%),C is sodium citrate content (%). A typical 3D surface plot, showing the compared effect of cow milk with buffer solution and goat milk with buffer solution is presented in Fig. 2. a) b) This study demonstrated that mathematical model was useful in evaluating the effects of factors leading to a higher survival of the lactic acid bacteria cells. The analysis of obtained results shows that the use of goat milk resulted in increased viability of lactic acid bacteria strains during freeze-drying, in comparison with cow milk-based protective medium, that is important for maintaining their biotechnological properties.