Vitamin B12 biosynthesis over waste frying sunflower oil as a cost effective and renewable substrate.

Statistical experimental designs were used to develop a medium based on waste frying sunflower oil (WFO) and other nutrient sources for production of vitamin B12 (VB12) by Propionibacterium freudenreichii subsp. freudenreichii PTCC 1674. The production of acetic acid and propionic acid were also evaluated using the same microorganism. The amount of WFO in the media was initially optimized. The amount of 4 % w/v of oil found to be an appropriate amount for production of VB12. A Plackett Burman design was then employed to identify nutrients that have significant effect on the production of VB12 in the WFO media. Dimethylbenzimidazolyl (DMB), cobalt chloride, ferrous sulfate, and calcium chloride were the most important compounds. The level optimization of nutrients as the significant factors was finally performed using response surface methodology based on a central composite design. The model predicted that a medium containing 35.56 mg/L DMB, 14.69 mg/L CoCl2.6H2O, 5.82 mg/L FeSO4.7H2O, and 11.41 mg/L CaCl2.2H2O gives the maximum VB12 production of 2.60 mg/L. The optimized medium provides a final concentration of vitamin 170 % higher than that by the original medium. This study offers valuable insights on a cost-effective carbon source for industrial production of food-grade VB12.