4A & 4B, where incorrect glycolysis∶pentose pathway split ratios gave no acceptable model.
For each glycolysis∶pentose pathway split ratio, an ensemble of 1500 models was constructed using Matlab (Mathworks, Natick, MA) on an Intel (Santa Clara, CA) Pentium 4 processor running Microsoft (Redmond, WA) Windows XP.
To account for this additional degree of freedom in determining the steady state flux, we calculate the flux map for a variety of glycolysis:pentose phosphate pathway split ratios (25∶75, 50∶50, 75∶25 and 95∶5) and carry out the EM approach using each of these varying flux maps to examine the effect of the split ratio on the modeling results.
After determining that these three parameters were significantly distributed in the screened models, a hierarchical clustering analysis was performed examining these three free enzyme fractions in the original ensemble of models for the 95∶5 glycolysis∶pentose pathway split, as shown in Figure 7B.
Thus, a low co-morbidity of two metabolically linked diseases would indicate a missing link along a Co-set, which would break the flux coupling by creating a pathway split.
Two pathway splitting strategies for monacolin J, and four for lovastatin were tested at different metabolic nodes.
To overcome limitations imposed by accumulation of intermediates and metabolic stress in monoculture, approaches using pathway splitting and co-culture were developed.
Pathway splitting and coculture could be combined with an increase in gene dosage and modification and expression of a statin pump protein in the future, and this strategy may further improve lovastatin production.
P. p/LV_V 9 produced 287.5 ± 2.0 mg/L lovastatin after 84 h (Fig. 5c), which was 267% higher than the productivity of the strain with a single copy of the biosynthetic genes (P. p/LV_SC), and even 15% higher than the productivity of the optimal pathway splitting and coculture strategy applied to the strains with a single copy of biosynthetic genes (Liu et al. 2018).
