In the BSc thesis a possibility of lactic acid fermentation of algae was investigated. Some literature sources show an improvement in functionality of products treated with lactic acid fermentation. Thus, experiments on improving algal products with the use of lactic acid fermentation are becoming more common. The results of our experiment represent the first step in the process of lactic acid fermentation of algae - in our case microalgae, Arthrospira platensis (Spirulina) and Chlorella vulgaris (Chlorella). We used a modified MRS agar as the substrate for the experiment, where carbon source (glucose) was replaced with microalgal dried powder (either Chlorella or Spirulina) as the sole source of carbon. We inoculated the agar plates with 5 different strains of lactic acid bacteria from the genus Lactobacillus and their growth and lactic acid production were monitored. After 3-4 days incubation at anaerobic conditions all strains showed good growth, where the best growth was observed for Lb. plantarum NCDO 1193/IM 212 and Lb. plantarum LMG 6907/IM 527. Furthermore, the microbial metabolism of carbon source in the medium was confirmed with the decrease of pH, indicating lactic acid production.