Evaluation of Growth and Utilization Potential of Rhodobacter sphaeroides in Reused Medium

Rhodobacter sphaeroides is a metabolically versatile purple non-sulfur bacteria that can produce valuable substances. As the low-cost and high-efficiency production of valuable substances is attracting attention, the reuse of the medium is emerging as a promising strategy. Therefore, in this study, the growth of R. sphaeroides was evaluated by reusing the medium of Escherichia coli and Saccharomyces cerevisiae. As a result, in the reuse of the medium in which S. cerevisiae was cultured, sufficient growth of R. sphaeroides could be confirmed, and especially, the growth of R. sphaeroides was not inhibited under aerobic conditions. Therefore, it is considered that the strategy of reusing the medium of S. cerevisiae is sufficiently feasible. Of the organic compounds investigated, R. sphaeroides grew best in succinic acid, followed by malic acid, citric acid, acetic acid, and glucose. In addition, by comparing photopigment synthesis in the reused medium, we propose the hypothesis that succinic acid may play an important role in photopigment synthesis for the first time.