Investigations on riboflavin production by wild-type yeast strain for supplementation of organic feed

Supplementation of vitamin B2 (riboflavin) in poultry feeding is essential. For economic and environmental reasons, riboflavin is now produced biotechnologically, which, in most industrial production, is based on genetically modified organisms (GMOs). Due to legislation, organic animals must be fed with GMO-free feeds, which also applies to the production processes of vitamin additives in the feed. Therefore, the main objective of experiments in this paper is the screening of GMO-free wild-type yeast strains overproducing riboflavin as a starting point to develop GMO-free riboflavin production lines that ensure the continuous supply of riboflavin for organic livestock. A screening of wild-type, non-GMO microorganisms overproducing riboflavin was conducted. The wild-type yeast Meyerozyma guilliermondii DSM 11947 produced the highest riboflavin concentration in the screening procedure. In order to provide a feasible and affordable certified organic animal vitamin B2 supplement, the possibility of minimizing the expensive media component, yeast extract, was shown. This work shows the possibility of using a wild-type strain to achieve higher levels of riboflavin by means of bioprocess engineering and without metabolic engineering. A fermentation strategy at the laboratory scale is provided, where a yield of 30 mg riboflavin per g dry matter of yeast cells was achieved.