Abstract: In this work, high cell density fed-batch fermentation was carried out to produce propionin with higher antibacterial activity. Starting from 96 h of fermentation, a mixed carbon source (sodium lactate:glucose = 3:1, m/m) and a mixed nitrogen source (yeast extract:corn distiller’s grains liquid = 1:30, V/V) (100 mL each, 2.5 g/L) were added at 24 h intervals for a total of 120 h. As a result, the antibacterial activity of propionin was increased from 17.6 to 31.2 AU/mL. In this study, we innovatively used corn distiller’s grains liquid as an alternative nitrogen source to partially replace yeast extract in order to greatly reduce the production cost of propionin. In addition, propionin was found to be a proteinaceous material with antibacterial activity as revealed by infrared spectroscopy and protease sensitivity experiments. The results of this study lay the foundation for industrial production and application of propionin.

Key words: high cell density fermentation, fed-batch feeding, corn distiller’s grains liquid, propionin