Characterization of High-Ornithine-Producing DB1 Isolated from Kimchi and Its Application in Rice Bran Fermentation as a Starter Culture.

High-ornithine-producing DB1 were isolated from kimchi. Ornithine is produced from arginine via the intracellular arginine deiminase pathway in microorganisms; thus, high cell growth is important for producing ornithine in large quantities. In this study, excellent DB1 growth (A: 5.15-5.39) was achieved in de Man, Rogosa, and Sharpe (MRS) medium supplemented with 1.0-3.0% arginine (pH 5.0) over 24-48 h at 30 °C, and the highest ornithine (15,059.65 mg/L) yield was obtained by culture in MRS containing 3.0% arginine for 48 h. DB1 was further investigated as a functional starter culture for rice bran fermentation. After 48 h of fermentation at 30 °C, the fermented rice bran was freeze-dried and ground. The prepared fermented rice bran contained 43,074.13 mg/kg of ornithine and 27,336.37 mg/kg of citrulline, which are used as healthcare supplements due to their beneficial effects. Furthermore, the organoleptic quality of the fermented rice bran was significantly improved, and the fermented product contained viable cells (8.65 log CFU/mL) and abundant dietary fiber. In addition, an investigation of its safety status showed that it has no harmful characteristics. These results indicate that the fermented rice bran product produced is a promising functional food candidate.