Characterization of mixed organic compounds extracted from Rhodobacter sphaeroides and applications to enhance the physiological responses of fermenting microorganisms

Photosynthetic bacteria can produce physiologically active compounds (PACs). In this study, PACs extracted from Rhodobacter sphaeroides were aerobically grown in the dark for 48 h. Neutral monosaccharides and amino acids in PACs were characterized and changes in the features of PACs before and after hydrolysis were analyzed using Fourier transform infrared spectroscopy. The growth and fermentation efficiency of Escherichia coli and Saccharomyces cerevisiae were enhanced under PACs-supplemented conditions. S. cerevisiae showed enhanced ethanol production. PACs did not act as carbon sources. The mixed organic compounds in PACs enhanced the physiological activities of other organisms by acting as nutrients. Therefore, the productivity of industrial microorganisms can be enhanced through exposure to PACs.