Strain Improvement Program of Streptomyces roseosporus for Daptomycin Production

Daptomycin is a cyclic lipopeptide antibiotic with potent activity against gram-positive bacteria. It has a calcium-dependent mechanism of action that disrupts multiple features of the bacterial membrane function. This antibiotic is highly demanded due to its effectiveness against to microorganisms resistant to other antibiotics, including vancomycin-resistant Staphylococcus aureus (VRSA) and methicillin-resistant S. aureus (MRSA). Daptomycin is produced by fermentation of Streptomyces roseosporus, currently identified as Streptomyces filamentosus. However, low fermentation yields and high production costs are reported. This chapter describes a method of strain improvement involving random mutagenesis, rational screening by bioassay, and flask fermentation. The ultimate objective is to select mutants of S. roseosporus overproducing daptomycin in order to design a more cost-effective daptomycin production.