Development of a chemically defined medium for the production of the antibiotic platensimycin by Streptomyces platensis

Abstract

The actinomycete Streptomyces platensis produces two compounds that display antibacterial activity: platensimycin and platencin. These compounds were discovered by the Merck Research Laboratories, and a complex insoluble production medium was reported. We have used this medium as our starting point in our studies. In a previous study, we developed a semi-defined production medium, i.e., PM5. In the present studies, by varying the concentration of the components of PM5, we were able to develop a superior semi-defined medium, i.e., PM6, which contains a higher concentration of lactose. Versions of PM6, containing lower concentrations of all components, were also found to be superior to PM5. The new semi-defined production media contain dextrin, lactose, MOPS buffer, and ammonium sulfate in different concentrations. We determined antibiotic production capabilities using agar diffusion assays and chemical assays via thin-layer silica chromatography and high-performance liquid chromatography. We reduced crude nutrient carryover from the seed medium by washing the cells with distilled water. Using these semi-defined media, we determined that addition of the semi-defined component soluble starch stimulated antibiotic production and that it and dextrin could both be replaced with glucose, resulting in the chemically defined medium, PM7.

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

“…However, many of the natural congeners were isolated from fermentations as large as 3400 L at titers as low as 3 µg L −1 [24, 28, 29]. Semi-defined and chemically defined media for PTM production in S. platensis MA7327 have also been reported [53, 54]. Although the titers of PTM under these conditions are less than those in previous reports, they support PTM and PTN production in simple, defined, and soluble medium.…”

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

“…In our optimized fermentation medium, soybean flour was used to replace yeast extract as nitrogen source, and soluble starch was used to replace dextrin and α-lactose as carbon source. Interestingly, soluble starch was also observed to stimulate PTM production in S. platensis MA7327 (Falzone et al 2013). However, the concentration of soybean flour seemed more critical than the soluble starch because the production media containing 7.5 g/L soybean flour could only produced PTM with a titer less than 400 mg/L, while the media with higher soybean flour concentration (> 10 g/L) minimally produced 1000 mg/L PTM, regardless of the soluble starch concentration used (Fig.…”

“…Singh and his colleagues obtained a PTM titer of 52 mg/L from S. platensis MA7327 in a 50 L CLA production medium (mainly consisting of yellow corn meal, lactose and ambrerex) (Zhang et al 2011). Demain and his colleagues developed several semi-defined or chemically-defined media for S. platensis MA7327, all of which supported PTM production (Aluotto et al 2013; Falzone et al 2013). …”

Evaluation of fermentation conditions triggering increased antibacterial activity from a near-shore marine intertidal environment-associated Streptomyces species

“…After eight days of fermentation, flasks (in replicates for each different media used) were removed and spun at 10,000 rpm to remove cell matter and cease the fermentation. This step was repeated at days 16, 20 and 24 and the resulting fermentation broth was collected and refrigerated at −4 °C [22] . Agar plug tests …”