3.3 Small amounts of required amino acids in α-ketoglutarate
module
The metabolism of arginine and histidine is involved in the synthesis of
the intermediate α-ketoglutarate of TCA cycle (Figure 1), which also
showed relatively small amounts of required supplements to restore cell
growth (Figure S3). Therefore, the lower concentrations of arginine and
histidine (20, 60, and 100 mg/L) were adopted to cultivated the
auxotrophic strains to evaluate their roles in cell growth and FFA
production (Figure 4).
his3 Δ had little impact on cell growth and FFA production, and
the auxotrophic strain reached the optimal behavior of control strain in
60 mg/L of histidine. The performance of strain did not continue to
improve when the concentration was further increased to 100 mg/L.
Different from histidine, while supplementing 60 mg/L of arginine, the
OD600 and FFA titer were only 60% and 30% of those in
control strain within 48 h, respectively (Figure 4B, D). The minimal
required amount of arginine was approximately 100 mg/L.