Members of the Streptomyces genus are known for the production of various secondary metabolites, such as broad spectrum antibiotic oxytetracycline. In the past decade, however, actinomycetes have raised the interest of researchers as candidate cell factory for heterologous protein expression. In the scope of this work, we selected three Streptomyces rimosus strains, constructed and tested for the expression of heterologous gene encoding caminisine, fused with the fluorescent protein mCherry reporter system. In the experimental part, with the aim of re-optimizing the standard bioprocess, we defined the growth morphology of the selected strains in liquid media, tested the influence of various inoculum sources on culture growth and protein production. Optimization was carried out at 40 mL and 5 mL scale, which was scaled down to a smaller scale of 3 mL. Upon successful transition to a smaller scale, we explored the possibilities of modifying the standard growth medium to accomodate higher bioprocess productivity. Replacing the nitrogen source casein tryptone by soy flour and soy protein concentrate led to a significant change in the production of the heterologous protein. Compared to tryptone, we achieved at least 30 % higher fluorescence values of the mCherry in the medium containing soy flour protein isolate.
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