Effect of ultrasonic treatment on metabolic activity of Propionibacterium shermanii, cultivated in nutrient medium based on milk whey

Utilization of milk whey still remains one of the most serious problems of the modern world dairy industry. Because of high biological value of whey it can be used as nutrient media in techniques of direct microbiological synthesis of complex high-molecular substances, for example the B12 vitamin, which participate in various biocatalytic reactions in organism providing normal functioning of the brain, nervous and hematogenic systems. The main industrial producer of B12 vitamin is Propionibacterium shermanii species, which can use lactose as main carbon source and can develop directly in milk whey. However, common ways of vitamin B12 microbiological production can’t be applied on the food plants and there must be used alternative safe methods, such as ultrasonic treatment of the cell culture, which can carry out the direct modulation of metabolic activity of bacteria for increasing of a yield of B12 vitamin. For the definition of ultrasonic processing influence on metabolism of Propionibacterium freudenreichii ssp. shermanii industrial strain it was cultivated in the nutrient media based on milk whey and treated by low intensity ultrasound at a frequency of 20 kHz within 10 and 20 min each 24 h. Received results allow to suggest that ultrasonic modulation of propionic bacteria metabolic activity can be used for an intensification of B12 vitamin biotechnological obtaining and manufacturing of fermented food products based on milk whey and enriched with B12 vitamin.