Production of protein and fatty acids in the anaerobic fermentation of molasses byE. ruminantium

Production of protein and volatile fatty acids by anaerobic digestion of blackstrap molasses was investigated. This protein may have potential as a feed for animals (and, we hope, for humans) in the near future. Volatile fatty acids can be further fermented to produce methane. Fermentation of molasses byEubacterium ruminantium was studied in a chemostat at a constant temperature of 37 C. This study focused on kinetics of growth of the pure culture. The maximum rate of protein production of about 0.326 g/l/hr was obtained when the pH and retention times were 6.2 and between 5 and 7 hrs, respectively. Average cell yield was 12.6% and carbohydrate conversion was 82 to 99%. Volatile fatty acids also were produced, with acetic acid and n-butyric acid being the predominant products. Two different kinetic models were used to fit the experimental data. The kinetic parameters obtained for the Monod model were: μmax=0.207 (1/hr); k_s=0.165 g/l.