Cyanofactory Platform to Photosynthetically Produce Advanced Fuels and Chemicals, While Providing Bioregenerative Life Support Services South Dakota State University/NASA Ames Research Center, Human Exploration & Operations Mission Directorate
Bubble-column reactors and Cyanobacteria culture
Total linalool accumulated from LinS Anabaena (LinS) and LinS-DXP Anabaena (LinS-DXP) during 14 days.
Dr. William Gibbons, Science PI, South Dakota State University
NASA EPSCoR Stimuli 2014 -15
Dr. Joseph Skiles, NASA Technical Monitor, Ames Research Center
To enable cyanobacteria to produce linalool or limonene from CO2 and H2O, the respective synthase genes have been successfully integrated into the N2fixing cyanobacterium Anabaena sp. PCC7120. The first reported photosynthetic production and secretion of these biofuel molecules has been confirmed by GC-MS. Subsequent genetic optimization of the underlying metabolic pathway (by over-expressing three key genes) has increased linalool production by 2-3 fold (figure at left) and limonene by 7-9 fold (published in Green Chem 16 (6), 3175 – 3185). The maximum linalool productivity was ~1.7μg/L/h when nitrate was used as the sole nitrogen source, and ~1.3μg/L/h when atmospheric N2 was the sole nitrogen source. Linalool and limonene produced by the engineered N2-fixing cyanobacterium is secreted into the growth medium and volatilized into the flask headspace, allowing easier product recovery. To improve productivity, Anabaena has been subjected to directed evolution that has resulted in increased tolerance to these chemicals. To improve technical and economic feasibility, we have worked to optimize the design and operation of photobioreactor systems that have integrated product recovery systems. Several bubble column reactors have been designed and tested with specific focus on gas flow and illumination (intensity and light-dark cycles). The optimum conditions for cyanobacteria cultivation were: 24:0 L-D periods, L.I of 68 µmol.m-2.s-1 and enriched air flow of 4.4 l.min-1. The optimum conditions for cyanobacteria cultivation were: 24:0 L-D photoperiods, Light Intensity of 68 µmol/m2/sec and enriched air flow of 4.4 liter/min. At this optimal condition, the growth rate was 2.5 g/liter/day and lipid productivity was 389±5 mg/g biomass. A company, CyanoSun Energy, was formed in 2012 to commercialize this technology. US Patent 8,993,303 “Genetically engineered cyanobacteria” was awarded on 3/31/2015 to PIs Zhou and Gibbons.
Published on Dec 14, 2015
NASA Office of Education’s Aerospace Research & Career Development (ARCD) is pleased to release NASA EPSCoR Stimuli, a collection of univers...