Abstract
We previously reported that Synechococcus elongatus PCC 7942, engineered with the sucrose transporter CscB, can export up to 85% of its photosynthetically-fixed carbon as sucrose and shows considerable promise as an alternative carbohydrate source. One approach to effectively utilize this cyanobacterium is to generate synthetic, light-driven consortia in which sucrose-metabolizing heterotrophs catalyze the conversion of the low-value carbohydrate into higher-value compounds in co-culture. Here, we report an improved synthetic photoautotroph/chemoheterotroph consortial design in which sucrose secreted by S. elongatus CscB directly supports the bacterium Halomonas boliviensis, a natural producer of the bioplastic precursor, PHB. We show that alginate encapsulation of S. elongatus CscB enhances sucrose-export rates ~2-fold within 66 h, to ~290 mg sucrose L−1 d−1 OD750−1 and enhances the co-culture stability. Consortial H. boliviensis accumulate up to 31% of their dry-weight as PHB, reaching productivities up to 28.3 mg PHB L−1 d−1. This light-driven, alginate-partitioned co-culture platform achieves PHB productivities that match or exceed those of traditionally engineered cyanobacterial monocultures. Importantly, S. elongatus CscB/H. boliviensis co-cultures were continuously productive for over 5 months and resisted invasive microbial species without the application of antibiotics or other chemical selection agents.
Original language | English (US) |
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Pages (from-to) | 236-245 |
Number of pages | 10 |
Journal | Metabolic Engineering |
Volume | 44 |
DOIs | |
State | Published - Nov 2017 |
Externally published | Yes |
Keywords
- Bioplastic
- Co-culture
- Halomonas boliviensis
- Synechococcus elongatus PCC 7942
- Synthetic biology
ASJC Scopus subject areas
- Biotechnology
- Bioengineering
- Applied Microbiology and Biotechnology