P184: Does availability of the important (but elusive) metabolite glucose-1-phosphate limit avilamycin production?

Modern concepts have been applied to a commercial antibiotic (avilamycin) production process that uses an undefined complex medium with carbon and nitrogen feeds resulting in unknown physiological outcome(s). Deconstruction of the process revealed that phosphate limitation is required for initiation of antibiotic biosynthesis. We hypothesise this is due to the central role of glucose-1-phosphate (G-1-P) in providing avilamycin precursors. G-1-P can be considered a “rare” metabolite since it is only readily available during glycogen catabolism. In a carbon-rich process, phosphate limitation would result in enhanced glycogen accumulation, as in the absence of sufficient phosphate for maximum ATP production, storage carbohydrates are synthesised. This will later result in the release of copious quantities of G-1-P if conditions for re-utilisation of the storage compounds are imposed. A genome scale metabolic model has been constructed of the producing species to examine the accumulation kinetics of G-1-P under differing steady-state conditions; constraining the modelling process using data from chemostat culture experiments. Strategies to identify specific gene knock-outs that may result in increased levels of the antibiotic will be discussed, which will help to determine the importance of G-1-P released from glycogen to avilamycin biosynthesis. Sugars are frequently found in natural products, many of these derived from G-1-P, such as important commercial macrolide antibiotics (erythromycin, tylosin), antiparasites (avermectins), and anticancer drugs (doxorubicin). Therefore, discoveries regarding the importance of G-1-P availability in avilamycin production may apply to the biosynthesis of other deoxysugar containing natural products.