n-Butanol production by Rhodopseudomonas palustris TIE-1
Wei Bai, Tahina Onina Ranaivoarisoa, Rajesh Singh, Karthikeyan Rengasamy, Arpita Bose
Abstract
Abstract Anthropogenic carbon dioxide (CO 2 ) release in the atmosphere from fossil fuel combustion has inspired scientists to study CO 2 to biofuel conversion. Oxygenic phototrophs such as cyanobacteria have been used to produce biofuels using CO 2 . However, oxygen generation during oxygenic photosynthesis adversely affects biofuel production efficiency. To produce n -butanol (biofuel) from CO 2 , here we introduce an n -butanol biosynthesis pathway into an anoxygenic (non-oxygen evolving) photoautotroph, Rhodopseudomonas palustris TIE-1 (TIE-1). Using different carbon, nitrogen, and electron sources, we achieve n -butanol production in wild-type TIE-1 and mutants lacking electron-consuming (nitrogen-fixing) or acetyl-CoA-consuming (polyhydroxybutyrate and glycogen synthesis) pathways. The mutant lacking the nitrogen-fixing pathway produce the highest n -butanol. Coupled with novel hybrid bioelectrochemical platforms, this mutant produces n -butanol using CO 2 , solar panel-generated electricity, and light with high electrical energy conversion efficiency. Overall, this approach showcases TIE-1 as an attractive microbial chassis for carbon-neutral n- butanol bioproduction using sustainable, renewable, and abundant resources.