Bio-oil based biorefinery strategy for the production of succinic acid

Abstract

Background: Succinic acid is one of the key platform chemicals which can be produced via biotechnology process instead of petrochemical process. Biomass derived bio-oil have been investigated intensively as an alternative of diesel and gasoline fuels. Bio-oil could be fractionized into organic phase and aqueous phase parts. The organic phase bio-oil can be easily upgraded to transport fuel. The aqueous phase bio-oil (AP-bio-oil) is of low value. There is no report for its usage or upgrading via biological methods. In this paper, the use of AP-bio-oil for the production of succinic acid was investigated.

Results: The transgenic E. coli strain could grow in modified M9 medium containing 20 v/v% AP-bio-oil with an increase in OD from 0.25 to 1.09. And 0.38 g/L succinic acid was produced. With the presence of 4 g/L glucose in the medium, succinic acid concentration increased from 1.4 to 2.4 g/L by addition of 20 v/v% AP-bio-oil. When enzymatic hydrolysate of corn stover was used as carbon source, 10.3 g/L succinic acid was produced. The obtained succinic acid concentration increased to 11.5 g/L when 12.5 v/v% AP-bio-oil was added. However, it decreased to 8 g/L when 50 v/v% AP-bio-oil was added. GC-MS analysis revealed that some low molecular carbon compounds in the AP-bio-oil were utilized by E. coli.

Conclusions: The results indicate that AP-bio-oil can be used by E. coli for cell growth and succinic acid production.

Figure 1

Co-production of high quality bio-oil and succinic acid from biomass treated by both thermochemical and biotechnological processes.

Figure 2

Bacterial growth in test of the media. a: bacterial growth in modified M9 media; b: bacterial growth in the traditional fermentation media with or without Fermentation components; c: bacterial growth in the traditional fermentation media with low concentrations of AP-bio-oil.

Figure 3

Succinic acid production with different percentages of AP-bio-oil with or without Fermentation components. a: glucose variation during the aerobic phase; b: glucose variation during the anaerobic phase; c: succinic acid fermentation during the anaerobic phase.

Figure 4

GC-MS analysis of AP-bio-oil components before and after fermentation. a: fermentation medium with 50% AP-bio-oil; b: fermentation medium with 100% AP-bio-oil. Peaks for possible components: 1:3-methyl-butanal; 2: ethanol; 3: acetic acid 4: 2, 3-dihydro-3, 5-dihydroxy-6-methyl-4H-Pyran-4-one; 5: dimethoxy phenol.

Figure 5

Production of succinic acid with biomass pretreated by both biotechnological and thermal process. AP-bio-oil concentration: (a) 0%; (b) 2.5%; (c) 5%; (d) 12.5%; (e) 25%; (f) 50%.