NUTRITIONAL ENHANCEMENT OF DRIED DISTILLER'S GRAINS WITH SOLUBLES VIA SPOROBOLOMYCES ROSEUS FERMENTATION

Abstract Text: Whole stillage and thin stillage from the ethanol production process were evaluated as substrate sources for the production of β-carotenes by Sporobolomyces Roseus (ATCC28988). This product has the potential to be used as a novel feed ingredient for poultry, swine or cattle diets. β-carotenes have been supplemented in animal diets, typically from 150 mg/kg to 300 mg/kg to improve animal health, enhance meat color and quality and increase vitamin A levels in milk and meat. By supplementing a stillage fermentation with easily consumable carbon sources and protein sources the fermentation lag time will be reduced and the protein levels of the resultant product will be unaffected or increased. Microbial growth kinetics and stillage fermentations were performed in 500-ml baffled shake flasks and in a 5 L fermentation bioreactor. HPLC method was used to analyze and quantify the β-carotenes. A 50 L bioreactor has been specifically designed to evaluate the scalability of the process and to perform subsequent feed production trails. Media optimization was conducted in shake flasks using supplemented glucose or glycerol and ammonium sulfate or urea.  By supplementing the fermentation with additional protein sources which are easily consumed by the microbes, such as urea, the protein level of the resultant feed ingredient would be unaffected.  Final β-carotene concentration was found to be highest for the whole stillage, with 10 g/L added glucose and 10 g/L nitrogen added through ammonium sulfate, at 272.57±4.34 µg β-carotene/g biomass.  Glycerol addition yielded no significant increase (p>.05) in β-carotene yield, while urea addition significantly decreased (p<.05) the final β-carotene concentrations.  The resulting fermented product can be effectively blended with regular feed to generate a premium nutritionally enhanced feed product using either whole stillage as a dry feed ingredient or thin stillage as a liquid feed additive. 

Keywords: Beta Carotene, DDGS, Feed, Fermentation