Abstract

DNA crown cells are artificial cells in which the outside of the membrane is coated with DNA. DNA crown cells (artificial cells) can be generated by incubating cells within egg white containing a sphingosine (Sph)-DNA-adenosine mixture. Previous research investigating the contribution of DNA crown cells to applied fields demonstrated that antibiotics are produced by co-cultures of yeast (beer) with DNA crown cells when the latter are generated using DNA from the antibiotic-producing Streptomyces griseus. However, many problems remain in the characterization of these phenomena. Notably, there is a long delay between the initiation of the co-culture and antibiotic production, either about 5 weeks when using DNA crown cells in egg white or about 15 days when using purified cells.
The present experiments were carried out to resolve the mechanism of antibiotic production, especially the issue of the delay in antibiotic production in co-culture systems. The present study demonstrated that antibiotic was produced after 5 days of co-culturing at small scale (1mL malt) and that the yeast was unable to grow once antibiotic production initiated. Based on these results, I propose the following mechanism for antibiotic production in this co-culture system. Time until antibiotic was detected may be influenced by the volume of malt used and the ratio of contact between the DNA crown cells and yeast. Notably, antibiotic was detected after 5 days of culturing at small scale (using 1mL malt and cells incubated with yeast (3mg) in 2mL egg), after 17 days at intermediate scale (using 30mL malt and cells incubated with yeast (0.3g) in 6mL egg white), and after 5 weeks at large scale (using 10L malt and cells incubated with yeast (5g) in 20mL egg white).
Yeast that were in contact with DNA crown cells produced antibiotic, but were unable to grow after the initiation of antibiotic production. The remaining yeast that were not in direct contact with the DNA crown cells continued to grow and produce antibiotic and to accumulate the antibiotic. Further experiments will be needed to validate this proposed mechanism. With or without such validation, there remain several problems that will need to be addressed, including whether DNA crown cells in fact are killing the cocultured yeast

Keywords: Antibiotic;Beer; DNA crown cells;Streptomyces griseus;Yeast