Metabolic engineering of roseoflavin-overproducing microorganisms

Abstract

Background Roseoflavin, a promising broad-spectrum antibiotic, is naturally produced by the bacteria Streptomyces davaonensis and Streptomyces cinnabarinus . The key enzymes responsible for roseoflavin biosynthesis and the corresponding genes were recently identified. In this study we aimed to enhance roseoflavin production in S. davaonensis and to synthesize roseoflavin in the heterologous hosts Bacillus subtilis and Corynebacterium glutamicum by (over)expression of the roseoflavin biosynthesis genes. Results While expression of the roseoflavin biosynthesis genes from S. davaonensis was not observed in recombinant strains of B. subtilis , overexpression was successful in C. glutamicum and S. davaonensis . Under the culture conditions tested, a maximum of 1.6 ± 0.2 µM (ca. 0.7 mg/l) and 34.9 ± 5.2 µM (ca. 14 mg/l) roseoflavin was produced with recombinant strains of C. glutamicum and S. davaonensis , respectively. In S. davaonensis the roseoflavin yield was increased by 78%. Conclusions The results of this study provide a sound basis for the development of an economical roseoflavin production process. Electronic supplementary material The online version of this article (10.1186/s12934-019-1181-2) contains supplementary material, which is available to authorized users.

Multiple copies of the oxytetracycline gene cluster in selected Streptomyces rimosus strains can provide significantly increased titers

“…Augmenting ‘gene dosage’ by amplification of the target gene or the entire biosynthetic pathway might instead be a successful strategy [ 9 ]. This can be achieved by expression of the target biosynthetic pathway on a replicative plasmid, which is maintained in the host in multiple copies [ 10 ]. Alternatively, multiple copies of genes that encode the biosynthesis of a target product can be integrated into the chromosomes [ 11 ].…”

The roseoflavin producer Streptomyces davaonensis has a high catalytic capacity and specific genetic adaptations with regard to the biosynthesis of riboflavin

“…In subsequent reactions, the enzymes RosB (EC 2.6.1.114) (Schwarz et al ., 2016; Konjik et al ., 2017), RosC (unpublished) and RosA (EC 2.1.1.343) (Jankowitsch et al ., 2011) synthesize roseoflavin from FMN. There is strong evidence that roseoflavin is exported from the cytoplasm of the producer cells and about 20 μM roseoflavin (8 mg l −1 ) can be found in the culture supernatant of cells grown to the stationary phase in a specific starch and yeast extract containing growth medium (Mora‐Lugo et al ., 2019). This is the only growth medium known to support roseoflavin formation.…”

Advances in metabolic engineering of Corynebacterium glutamicum to produce high-value active ingredients for food, feed, human health, and well-being

“…In addition to amino acids, plant (poly)phenols, terpenoids, extremolytes, and medical polymers, have been showcased here. C. glutamicum was recently shown to produce antibiotics such as roseoflavin [136], vitamins such as d-pantothenate [137] and vitamin B 2 [138], and diagnostic biomarkers for the characterisation of various cancer types such as l-2-hydroxyglutarate [139], N-alkylated amino acids such as N-methyl-l-alanine [140], and N-ethyl-sarcosine [141], as well as chlorinated or brominated l-tryptophans [142,143] for the synthesis of peptide drugs, promising an even wider portfolio in the future. In addition, the functional expression of type I polyketide synthase, renders C. glutamicum a promising microbial cell factory to produce type I polyketide synthase-derived high-value molecules.…”