Effects of glucose limitation on biomass and spiramycin production by Streptomyces ambofaciens

Abstract

Spiramycin production by Streptomyces ambofaciens Sp181110 with glucose as the carbon source was studied under a controlled nutritional environment. In a batch culture, the glucose excess after ammonium depletion led to pyruvate and alpha-ketoglutarate accumulation. 85 mg/l of spiramycin were produced in less than 70 h during the stationary and maintenance phase on these acids after glucose exhaustion. Fed-batch strategy was designed to study spiramycin production without by-product formation and glucose accumulation. In these conditions, up to 150 mg/l were produced in less than 80 h during the stationary phase on glucose. The antibiotic titre was found independent of the glucose feeding under carbon limitation and the importance of putative intracellular reserves formed after nutrient exhaustion was suggested. Besides, spiramycin production was not inhibited by the limiting flux of glucose.

Time-Resolved Transcriptomics and Constraint-Based Modeling Identify System-Level Metabolic Features and Overexpression Targets to Increase Spiramycin Production in Streptomyces ambofaciens

“…Comparison between model-predicted growth rates and experimentally determined ones on four minimum growth media providing different Carbon (C) and Nitrogen (N) sources (glucose and ammonium, glucose and valine, glycerol and ammonium, glycerol, and valine). The values reported by the blue bars correspond to measurements obtained from previously published works (Lounès et al, 1995, Lounès et al, 1996a,b; Colombie et al, 2005)…”

“…The reliability of the reconstructed S. ambofaciens model was inferred by comparing the predicted growth rates on a set of different minimal media against a set of experimentally determined ones available from previous studies (Lounès et al, 1995, 1996a,b; Colombie et al, 2005). Accordingly, in silico minimal growth media were defined using exchange reactions present in the model, and biomass optimization was selected as the model objective function (O.F.).…”

Amino acid uptake profiling of wild type and recombinant Streptomyces lividans TK24 batch fermentations

“…(e.g., Madden et al, 1996;Karandikar et al, 1997;Avignone Rossa et al, 2002;Corvini et al, 2004;Colombié et al, 2005). Pyruvate and ␣-ketoglutarate are well known overflow metabolites, allowing cells to deal with this excess carbon resulting from a carbon flux bottleneck between the glycolysis and the TCA cycle (Hodgson, 2000, Colombié et al, 2005.…”

Carbon source regulation of antibiotic production

“…97 In a batch culture under ammonium depletion, excess glucose led to pyruvate and a-ketoglutarate accumulation and maintained an antibiotic production phase from these acids after glucose exhaustion. 98 One of the conclusions from the above-mentioned information is that not all secondary metabolite genes are equally sensitive to carbon source regulation control. For instance, actinorhodin production is sensitive to glucose concentrations in the range of 100 mM; however, higher concentrations are necessary to repress doxorubicin production.…”