Titer improvement and pilot-scale production of platensimycin from Streptomyces platensis SB12026

Abstract

Platensimycin (PTM) and platencin (PTN), isolated from several strains of Streptomyces platensis, are potent antibiotics against multi-drug resistant bacteria. PTM was also shown to have antidiabetic and antisteatotic activities in mouse models. Through a novel genome-mining method, we have recently identified six PTM and PTN dual-producing strains, and generated several mutants with improved production of PTM or PTN by inactivating the pathway-specific transcriptional repressor gene ptmR1. Among them, S. platensis SB12026 gave the highest titer of 310 mg/L for PTM. In this study, we now report titer improvement by medium and fermentation optimization and pilot-scale production and isolation of PTM from SB12026. The fermentation medium optimization was achieved by manipulating the carbon and nitrogen sources, as well as the inorganic salts. The highest titer of 1560 mg/L PTM was obtained in 15-L fermentors, using a formulated medium mainly containing soluble starch, soybean flour, morpholinepropanesulfonic acid sodium salt and CaCO3. In addition, a polyamide chromatographic step was applied to facilitate the purification and 45.14 g of PTM was successfully obtained from a 60 L scale fermentation. These results would speed up the future development of PTM as human medicine.

In vivo instability of platensimycin and platencin: Synthesis and biological evaluation of urea- and carbamate-platensimycin

“…Given our capacity to produce PTM in excellent yields by fermentation, 13–18,28,29 we envisioned that both the urea and carbamate analogues could be easily accessed through a coupling reaction between a ketolide moiety and ADHBA or trihydroxybenzoic acid, respectively. Urea functional groups are much more stable to hydrolysis than amides 30 and several urea- and carbamate-containing compounds are clinically-relevant drugs or drug leads.…”

“…19,20 While total synthetic routes of both PTM and PTN are available, 26,27 titers of PTM from fermentation of SB12029 are >300 mg L −1,17,28 with pilot-scale production >1.5 g L −1 29 . These high titers significantly reduce the time and resources needed to access the PTM and PTN scaffolds.…”

Platensimycin and platencin: Inspirations for chemistry, biology, enzymology, and medicine

“…Exploiting a combination of pathway engineering and fermentation optimization, pilot scale production of PTM was developed. Manipulation of the medium and optimization of the fermentation procedures of one of the Δ ptmR1 strains, S. platensis SB12026, afforded PTM production titers of 1.56 g L −1 [56]. …”

A facile semi-synthetic approach towards halogen-substituted aminobenzoic acid analogues of platensimycin

“…With ample PTM in hands from the fermentation of S. platensis SB12026, 41 we began our investigation to obtain gram-quantity of PTMA ( 1d ) for semi-synthesis of PTM analogues with varying aminobenzoate moieties (Scheme 1). Singh and his co-workers obtained PTMA via a mild amide hydrolysis through NaNO 2 /CH 3 COOH/Ac 2 O with a moderate yield of about 60%.…”

“…However, the yield decreased dramatically for a large scale synthesis, which was probably due to the low solubility for PTM under acid conditions. 16,41 Therefore, EtOH was used as the solvent to make PTMA ethyl ester 1a , followed by the LiOH-mediated hydrolysis in a large scale synthesis. Thus 1.20 g of PTMA was obtained from 2.11 g of PTM with 85% overall yield in two steps (Scheme 1B).…”