Development Of Highly Active Virginiamycin-producing Strain And Improvement Of Its Productivity Using Synthetic Adsorbing Resins


V. A. Savushkin, V. V. Dzhavakhiya, E. V. Glagoleva, V. V. Savel'eva, E. D. Popova, A. I. Ovchinnikov, V. I. Glagolev, N. V. Novak, D. A. Durnikin

Virginiamycin, an antibiotic produced by some Streptomyces species, is widely used in veterinary and bioethanol production. It represents a natural mix of two different macrocyclic components, among which M1 and S1 factors are the main acting components. M1 and S1 act synergistically when present in the optimum ratio of 60-75% of M1 and 25-40% of S1. Due to a large number of genes involved into the virginiamycin biosynthesis, the development of overproducing strains able to synthesize M1 and S1 at a synergistic ratio with the total productivity exceeding 3-4 g/L still remains a relevant problem. Using a multi-step random UV mutagenesis of the Streptomyces sp. strain DSM40559, a highly active strain S 15-30 was obtained, which virginiamycin titer on a basic medium significantly increased that of the parental strain (2.6 and 0.35 g/L, respectively), and the M1:S1 ratio remained synergistic (72:28). Various sources of carbon, nitrogen, and macroelements were evaluated for medium improvement, and several different types of synthetic macroporous resins were tested to provide the highest virginiamycin titer in culture broth of the developed strain. The resulting improved fermentation medium supplemented with 20 g/L of Amberlite XAD-16 resin increased strain productivity up to 5.03 ± 0.12 g/L with the simultaneous maintenance of the M1:S1 ratio within the synergistic range (72:28) and highly selective level of adsorption of the antibiotic from culture broth (92-95%). The variability of the M1:S1 ratio in the total antibiotic titer depending on various medium composition and resin type was first demonstrated. The obtained strain is promising for the industrial use due to its high productivity and the optimal M1:S1 ratio. Results of the study will be used for the further selection of overproducing strains and the scaling up of the virginiamycin production. The obtained data can be interesting for other researchers working in the field of production of macrolide antibiotics.


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