Enhancement of oxytetracycline production after gamma irradiation-induced mutagenesis of Streptomyces rimosus CN08 strain |
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Authors: | Hadeer Lazim Nedra Slama Houda Mankai Insaf Barkallah Ferid Limam |
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Affiliation: | 1.Unité de Microbiologie et Biologie Moléculaire,Centre National des Sciences et Technologies Nucléaires,Tunis,Tunisia;2.Laboratoire des Substances Bioactives,BP-901 Centre de Biotechnologie,Hammam-lif,Tunisia |
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Abstract: | Streptomyces rimosus CN08 isolated from Tunisian soil produced 8.6 mg l−1 of oxytetracycline (OTC) under submerged fermentation (SmF). Attempts were made for enhancing OTC production after irradiation-induced mutagenesis of Streptomyces rimosus CN08 with Co60-γ rays. 125 OTC-producing colonies were obtained after screening on kanamycin containing medium. One mutant called Streptomyces rimosus γ-45 whose OTC production increased 19-fold (165 mg l−1) versus wild-type strain was selected. γ-45 mutant was used for OTC production under solid-state fermentation (SSF). Wheat bran (WB) was used as solid substrate and process parameters influencing OTC production were optimized. Solid-state fermentation increased the yield of antibiotic production (257 mg g−1) when compared with submerged fermentation. Ammonium sulphate as additional nitrogen source enhanced OTC level to 298 mg g−1. Interestingly, OTC production by γ-45 mutant was insensitive to phosphate which opens the way to high OTC production even in medium containing phosphate necessary for optimal mycelia growth. |
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