Construction and analysis of an artificial consortium based on the fast-growing cyanobacterium Synechococcus elongatus UTEX 2973 to produce the platform chemical 3-hydroxypropionic acid from CO2

• Published in: Biotechnology for biofuels 2020-05, Vol.13 (1), p.1-82, Article 82
• Main Authors: Zhang, Li, Chen, Lei, Diao, Jinjin, Song, Xinyu, Shi, Mengliang, Zhang, Weiwen
• Format: Article
• Language: English
• Subjects: 3-Hydroxypropionic acid; Acids; Artificial consortium; Bacteria; Biosynthesis; Carbohydrates; Carbon; Carbon dioxide; Cell culture; Cell growth; Chemicals; Climate change; Consortia; Conversion; Cultivation; Cyanobacteria; E coli; Elongation; Escherichia coli; Feasibility studies; Fermentation; Fine chemicals; Genes; Growth conditions; Heterotrophic bacteria; Industrial applications; Manufacturing costs; Microorganisms; Oxidative stress; Permease; Photosynthesis; Physiological aspects; Plant biochemistry; Production costs; Productivity; Purification; Raw materials; Reactive oxygen species; Studies; Sucrose; Sucrose permease; Sugar; Symbiotic; Synechococcus elongatus
• ISSN: 1754-6834; 1754-6834
• DOI: 10.1186/s13068-020-01720-0

Cyanobacterial carbohydrates, such as sucrose, have been considered as potential renewable feedstock to support the production of fuels and chemicals. However, the separation and purification processes of these carbohydrates will increase the production cost of chemicals. Co-culture fermentation has been proposed as an efficient and economical way to utilize these cyanobacterial carbohydrates. However, studies on the application of co-culture systems to achieve green biosynthesis of platform chemicals are still rare. In this study, we successfully achieved one-step conversion of sucrose derived from cyanobacteria to fine chemicals by constructing a microbial consortium consisting of the fast-growing cyanobacterium Synechococcus elongatus UTEX 2973 and Escherichia coli to sequentially produce sucrose and then the platform chemical 3-hydroxypropionic acid (3-HP) from CO.sub.2 under photoautotrophic growth conditions. First, efforts were made to overexpress the sucrose permease-coding gene cscB under the strong promoter P.sub.cpc560 in S. elongatus UTEX 2973 for efficient sucrose secretion. Second, the sucrose catabolic pathway and malonyl-CoA-dependent 3-HP biosynthetic pathway were introduced into E. coli BL21 (DE3) for heterologous biosynthesis of 3-HP from sucrose. By optimizing the cultivation temperature from 37 to 30 [degrees]C, a stable artificial consortium system was constructed with the capability of producing 3-HP at up to 68.29 mg/L directly from CO.sub.2. In addition, cell growth of S. elongatus UTEX 2973 in the consortium was enhanced, probably due to the quick quenching of reactive oxygen species (ROS) in the system by E. coli, which in turn improved the photosynthesis of cyanobacteria. The study demonstrated the feasibility of the one-step conversion of sucrose to fine chemicals using an artificial consortium system. The study also confirmed that heterotrophic bacteria could promote the cell growth of cyanobacteria by relieving oxidative stress in this microbial consortium, which further suggests the potential value of this system for future industrial applications.