In silico Analysis of 1,4-butanediol Heterologous Pathway Impact on Escherichia coli Metabolism
The bio-based synthesis of 1,4-butanediol (BDO), a key compound in many industries, has recently been achieved in Escherichia coli, however the yield even in glucose was far below the theoretical maximum. Furthermore, the impact of the BDO pathway on cell metabolism is yet to be discovered. The main objective of this study was to in silico improve and analyze the production potential of BDO on glucose and glycerol and evaluate the interaction between native and non-native pathways for wild-type and mutant strains using a simple biosynthetic pathway. The maximum production potential and changes in metabolic fluxes were simulated by different objective functions (biomass and BDO) and the reactions with highest differences were identified under different environmental conditions. Considering the outcomes 80% of the reactions with significant flux change were identical for all conditions simulated. Flux variability analysis was carried out to decipher the variation of fluxes and flux span changes (SC) were calculated. To further analyse the reactions with SC over 1 mmol gDW-1h-1 and to calculate the correlation coefficients for WT and mutant strains uniform random sampling was carried out. Most important variations in correlation patterns were observed for reactions in the mutant model. On the other hand, the addition, elimination and optimization of different pathways significantly affected the pairwise correlation patterns as well as the entire solution space of the network. Keywords: 1,4-butanediol, E. coli, flux variability analysis, random sampling, in silico, COBRA