Submitted to: Fermentation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/2018
Publication Date: 4/19/2018
Citation: Johnston, D., Nghiem, N.P. 2018. Evaluation of sweet sorghum juice for the production of lysine using corynebacterium glutamicum. Fermentation. 4(29):1-8.
Interpretive Summary: Sorghum is a grain that can be grown in non-tropical climates and can be grown in marginal land and drier regions than corn. Sweet sorghum is a type of sorghum that contains high levels of sugar in its stems. Sweet sorghum stems can be harvested and pressed to produce a juice containing ready to ferment sugars. Utilizing this juice, experiments were conducted to determine if sweet sorghum juice could be fed to a lysine-producing microorganism, Corynebacterium glutamicum, to produce lysine, a high value amino acid used as an animal feed supplement. Fermentation experiments showed that lysine could be produced and there were no inhibitory issues with utilizing sweet sorghum juice. This information will be useful to feed supplement producers, farmers looking to diversify production and fermentation researchers.
Technical Abstract: Sweet sorghum juice is a liquid sugar feedstock that can be produced in non-tropical climates. Utilization of sweet sorghum juice as a feedstock for the production of lysine was investigated utilizing the auxotrophic mutant Corynebacterium glutamicum ATCC 21513 in stirred tank bioreactors. The juice alone was found to have inadequate nutrients for growth of the auxotroph, so the juice was supplemented with two levels of yeast extract and peptone. The supplemented juice could support growth and produce lysine from the available sugars. No inhibitory effects of the juice were found on the growth of the organism. The lysine concentrations reached 28.8 g/l in the batch fermentations with complete utilization of the available sugars and a conversion efficiency of 0.23 g/g.