Production of vitamin B12 by Propionibacterium freudenreichii subsp. shermanii ATCC 13673 on a soybean agro-industrial waste-based medium: bioprocess optimization in STR bioreactors

The production and use of plant-based foods are increasing based on health, ethical, and environmental concerns. However, plants do not synthesize vitamin B ₁₂ , thus the fortification of plant-based foods is highly recommended to prevent its deficiency. The aim of this work was to optimize vitamin B ₁₂ production by Propionibacterium freudenreichii subsp. shermanii ATCC 13673 growing on stirred tank bioreactors using the liquid acid protein residue of soybean, an agro-industrial waste, as medium culture. The influence of medium supplementation, pre-saccharification of sugars, and aeration strategies were investigated. The pH and temperature control were optimized applying the Design of Experiments (DoE) approach, using a central composite design. After the optimization process, the vitamin B ₁₂ production more than tripled (from ~ 1.5 mg • L ^− 1 up to 5 mg • L ^− 1 ). Further, cultures produced high biomass concentrations for this bacterium (> 6 g • L ^− 1 ), whilst increasing by three-fold the specific biomass yield of vitamin B ₁₂ (> 0.8 mg • g ^− 1 dry cell). This bioprocess based on cheap and available soybean agro-industrial waste and a GRAS microorganism can be an efficient alternative source of vitamin B ₁₂ production to fortify plant-based products in the future.