Efficient production of succinic acid from macroalgae hydrolysate by metabolically engineered Escherichia coli

• E. coli BS002 was created to produce succinic acid from L. japonica hydrolysate.
• Glucose and mannitol were two major fermentable sugars in hydrolysate.
• Mannitol was superior to glucose for succinic acid production due to higher yield.
• High titer and yield of succinic acid from macroalgae biomass were reported firstly.

In this study, microbial production of succinic acid from macroalgae (i.e., Laminaria japonica) was investigated for the first time. The engineered Escherichia coli BS002 exhibited higher molar yield of succinic acid on mannitol (1.39 ± 0.01 mol/mol) than glucose (1.01 ± 0.05 mol/mol). After pretreatment and enzymatic hydrolysis, L. japonica hydrolysate was mainly glucose (10.31 ± 0.32 g/L) and mannitol (10.12 ± 0.17 g/L), which was used as the substrate for succinic acid fermentation with the recombinant BS002. A final 17.44 ± 0.54 g/L succinic acid was obtained from the hydrolysate after 72 h dual-phase fermentation. The yield was as high as 1.24 ± 0.08 mol/mol total sugar, which reached 73% of the maximum theoretical yield. The results demonstrate that macroalgae biomass represents a novelty and economical alternative feedstock for biochemicals production.