Commercial riboflavin production by recombinant Bacillus subtilis: down-stream processing and comparison of the composition of riboflavin produced by fermentation or chemical synthesis
A novel process for riboflavin production using a recombinant Bacillus subtilis strain has been developed. Here we describe a down-stream processing procedure to obtain riboflavin qualities having a minimal content of 96% (‘feed-grade’) and 98% (‘food/pharma-grade’) riboflavin, respectively. Compared to riboflavin produced by chemical synthesis, products with improved chemical purity were obtained. All compounds representing more than 0.1% of the final products were identified. Feed-grade riboflavin material ex fermentation contained small amounts of amino acids and amino sugars and the biosynthetic riboflavin precursor dimethyl-ribityl-lumazine. All other side products found were derived from riboflavin, resulted from the purification procedure and were also found in riboflavin obtained by chemical synthesis. The Bacillus-produced riboflavin does not contain DNA. The data presented here were used to obtain product approval for the commercial application in the USA, Japan and the UK.