Corynebacterium glutamicum is a commonly applied host for the industrial production of amino acids. While valued for its robustness, it is somewhat inferior to competing strains such as Escherichia coli because of the relatively low growth rate of 0.40 h −1 in synthetic, industrial media. Accordingly, adaptive laboratory evolution (ALE) experiments were performed in continuous cultivation mode to select for a growth-improved host. To ensure industrial attractiveness, this ALE study aimed at a reduction of dependency on costly growth-boosting additives such as protocatechuate (PCA) or complex media supplements. Consequently, double selection pressures were installed consisting of a steady increase in growth rate demands and a parallel reduction of complex medium fractions. Selection yielded C. glutamicum EVO5 achieving 0.54 h −1 and 1.03 g Glc g CDW −1 h −1 in minimal medium without abovementioned supplements. Sequencing revealed 10 prominent mutations, three of them in key regulator genes.

Nocardia terpenica IFM 0406 is the producer of the immunosuppressants brasilicardins A-D. Brasilicardin is a promising compound because of its unique mode of action and its higher potency and reduced toxicity compared to today's standard drugs. However, production of brasilicardin is so far hampered as Nocardia terpenica IFM 0406 synthesizes brasilicardin in only low amounts and represents a human pathogen (biosafety level 2 BSL2). In order to achieve a safe and high yield production of brasilicardin A (BraA), the authors heterologously express the brasilicardin gene cluster in the nocardioform actinomycete Amycolatopsis japonicum (A. japonicum::bcaAB01), which is fast growing, genetically accessible and closely related to N. terpenica IFM 0406. In A. japonicum::bcaAB01, four brasilicardin congeners, intermediates of the BraA biosynthesis, are produced. Investigation of the genes flanking the previously defined brasilicardin biosynthetic gene cluster revealed two novel genes (bra0, bra12), which are involved in brasilicardin biosynthesis: bra12 encodes a transcriptional activator of the brasilicardin gene cluster. bra0 codes for a dioxygenase involved in methoxylation of brasilicardin. Based on this finding the authors are able to revise the proposed brasilicardin biosynthesis.

Brasilicardin A (1) consists of an unusual anti/syn/ anti-perhydrophenanthrene skeleton with a carbohydrate side chain and an amino acid moiety. It exhibits potent immunosuppressive activity, yet its mode of action differs from standard drugs that are currently in use. Further pre-clinical evaluation of this promising, biologically active natural product is hampered by restricted access to the ready material, as its synthesis requires both a low-yielding fermentation process using a pathogenic organism and an elaborate, multistep total synthesis. Our semi-synthetic approach included a) the heterologous expression of the brasilicardin A gene cluster in different non-pathogenic bacterial strains producing brasilicardin A aglycone (5) in excellent yield and b) the chemical transformation of the aglycone 5 into the trifluoroacetic acid salt of brasilicardin A (1 a) via a short and straightforward five-steps synthetic route. Additionally, we report the first preclinical data for brasilicardin A.

The bacterium Nocardia terpenica IFM 0406 is known as the producer of the immunosuppressant brasilicardin A. Here, we report the completely sequenced genome of strain IFM 0406, which facilitates the heterologous expression of the brasilicardin biosynthetic gene cluster but also unveils the intriguing biosynthetic capacity of the strain to produce secondary metabolites.