Microbial growth and modification of corn distillers dried grains with solubles during fermentation

Corn distillers dried grains with solubles (DDGS) were fermented with bacteria or yeast. The microbial growth on three DDGS media-unmodified DDGS, enzyme-pretreated DDGS, and supplemented DDGS – was compared with standard media. Comparative growth profile indicated peaks in microbial growths at different times. The highest specific growth rates (SGR) of 0.6, 0.54 and 0.51 h−1 were observed for Saccharomyces Boulardii on unmodified DDGS, yeast extract, and enzyme-modified DDGS, respectively. Pediococcus Acidilactici and Lactobacillus Plantarum had the SGR of 0.17 and 0.07 h−1, respectively, on control DDGS. However, L. Plantarum on unmodified DDGS demonstrated the highest cell count (2.91 × 1011 CFU/mL), followed by S. boulardii at 1.5 × 109 CFU/mL on YEPD, and P. acidilactici at 1.16 × 1010 CFU/mL on MRS (de Man, Rogosa and Sharpe) media. Protein digestibility of DDGS improved slightly due to fermentation, and resulted in reduced phytic acid content for some treatments. Production of lactic acid was highest on unmodified DDGS.

► We modified corn distillers dried grains with solubles (DDGS) by bacterial and yeast fermentation. ► DDGS with or without nutrient supplementation supported vigorous microbial growth. ► Yeast growth rate was approximately 5-fold higher than bacterial growth rates. ► Bacterial and yeast fermentation resulted in lower phytic acid in DDGS substrates. ► Production of lactic acid by bacteria was the highest on unmodified DDGS.