Dumping of milk whey with sewage causes large-scale losses of valuable milk components and increases the purification costs of
dairy plants wastes. Whey can be valuable nutrient medium for cultivation of microorganisms and direct biosynthesis of the
bioactive compounds, for example B12 vitamin. The main industrial producer of B12vitamin is Propionibacterium freudenreichii
ssp. shermanii. It can use lactose as a main carbon source and it is able to grow in milk whey. Condensed whey usage can cut
down expenses on transportation of the raw material and decrease the processing time and plant floor spaces needed for
cultivation. Propionibacterium culture and symbiotic culture of Acetobacter aceti were cultivated in the nutrient media based on
milk whey with different amount of solids for evaluation of lactose concentration influence on corrinoid formation. Joint
cultivation of Propionibacterium freudenreichii ssp. shermanii and Acetobacter aceti in the whey-based nutrient media with 10
% concentration of lactose is recommended for efficient production of condensed milk whey enriched by B12 vitamin.