Harnessing riboflavin production of food derived L. fermentum to develop a riboflavin bio-enriched oat beverage

Riboflavin is a key micronutrient and important precursor of the co-enzymes flavin mononucleotide (FMN) and flavin adenine-di-nucleotide (FAD) thereby playing a vital role in nutrient metabolism, growth and development of the human body. Some lactic acid bacteria (LAB) strains have the ability to produce riboflavin, a feature that is linked to the rib operon, and selection of roseoflavin spontaneous mutants has previously been shown as a method for obtaining riboflavin-overproducing LAB strains. The aim of the present work was to develop a riboflavin bio-enriched commercial vegetable beverage by its fermentation using a riboflavin-overproducing LAB strain. A riboflavin–overproducing spontaneous mutant (Ros 1.2) was initially obtained from a Limosilactobacillus fermentum strain isolated from buffalo milk, harboring the rib operon. After preliminary small-scale trials with L. fermentum Ros 1.2 in soy and oat beverages, riboflavin production in commercial oat beverage was optimized and scaled up to 3 L fermenters demonstrating a significantly increased riboflavin titer and productivity when switching fermentation from conventional laboratory media to commercial oat beverage under controlled conditions. To date, this is the first study that showed riboflavin bio-enrichment of a commercial oat beverage by a riboflavin-overproducing food derived L. fermentum strain.