Float methods to produce antibiotics in liquid culture for Actinomycetes

Isolated actinomycetes tend to face problems such as barely producing antibacterial substances when cultured in liquid. The Streptomyces strains we used faced the same problem. In this study, a float method was used to allow some strains to secrete antibiotics into a liquid medium at a relatively high concentration. • Many actinomycetes produce antibiotics in solid culture, but not in liquid culture. • The strains we used in this study also did not produce antibiotics in general liquid culture. • Our newly developed float culture method enabled DGK16 and TSO12 and TSP2-12 to produce antibiotics at high concentrations in liquid. • Float culture is likely to be effective for other microorganisms that are facing problems in other liquid culture.