The effect of citrate supplementation on medium viscosity and poly-γ-glutamic acid synthesis by engineered B. subtilis 168

ABSTRACT: The industrially attractive biopolymer Poly-γ-glutamic acid (γ-PGA) is commonly produced by species of the genus Bacillus by co-feeding different carbon- and nitrogen sources. Recent studies have highlighted the pivotal role of co-metabolization of a rapidly degradable carbon source such as glycerol together with citrate for γ-PGA production, independently fueling biomass generation as well as TCA cycle precursor supply. With this study, we report that the sole presence of citrate in the production medium greatly influences growth behavior, γ-PGA production, and the viscosity of microbial cultures during biopolymer synthesis. Independent of the citrate concentration in the medium. only minor amounts of citrate were imported by B. subtilis 168 in presence of glycerol due to carbon catabolite repression. However, a high citrate concentration resulted in a 6-fold increase in γ-PGA titer as compared to low levels of exogenous citrate. Data suggests that citrate was not used as a precursor in γ-PGA synthesis but rather influenced the fate of imported glutamate. The citrate concentration also affected medium viscosity as depletion resulted in a remarkable spike in broth viscosity. Additionally, cellular proteome analysis at different levels of citrate availability revealed significant changes in protein abundance involved in motility and fatty acid degradation

INSTRUMENT(S): LTQ Orbitrap Elite

ORGANISM(S): Bacillus Subtilis Subsp. Subtilis Str. 168

SUBMITTER: Sandra Maass  

LAB HEAD: Dörte Becher

PROVIDER: PXD058048 | Pride | 2025-02-10

REPOSITORIES: pride