Influence of inoculum density and aeration volume on biomass and bioactive compound production in bulb-type bubble bioreactor cultures of Eleutherococcus koreanum Nakai

► In vitro conditions affect biomass and bioactive compound production in bioreactors. ► Inoculum density and aeration volume are main factors of adventitious root cultures. ► Physiological responses of roots are affected by gas components inside bioreactors. ► Optimizing culture conditions will be beneficial for the pilot-scale production. ► Eleutherococcus koreanum Nakai is an endemic medicinal plant contains useful bioactive compounds. This study deals with the effects of initial inoculum density and aeration volume on biomass and bioactive compound production in adventitious roots of Eleutherococcus koreanum Nakai in bulb-type bubble bioreactors (3-L capacity). While the fresh and dry weights of the roots increased with increasing inoculum density, the highest percentage dry weight and accumulation of total target compounds (eleutheroside B and E, chlorogenic acid, total phenolics, and flavonoids) were noted at an inoculum density of 5.0gL−1. Poor aeration volume (0.05vvm) stunted root growth, and high aeration volume (0.4vvm) caused physiological disorders. Moreover, an inoculum density of 5.0gL−1 and an aeration volume of 0.1vvm resulted in the highest concentration of total target compounds and least root death. Such optimization of culture conditions will be beneficial for the large-scale production of E. koreanum biomass and bioactive compounds.