I study the metabolism that drives photosynthetic H₂ production by Rhodopseudomonas palustris. H₂ is currently used in various industries and is receiving increasing attention as a clean-burning fuel. Most H₂ we use as a society is derived from fossil fuels. However, H₂ can be produced biologically from renewable resources using organisms like R. palustris. R. palustris obtains energy from photosynthesis and electrons from organic (and some inorganic) waste to produce H₂ via nitrogenase. A disadvantage of producing H₂ via nitrogenase is that it is repressed by ammonia, which is found in feedstocks for biological H₂ production. Fortunately, we have created mutants that produce H₂ even in the presence on ammonia. I compared one of these mutants to the wild-type strain using ¹³C-metabolic flux analysis and transcriptional approaches to identify metabolic pathways that affect H₂ production. I then used the resulting information to engineer a strain with higher H₂ yields. Currently, I am characterizing the metabolism and physiology of non-growing R. palustris cells where the highest H₂ yields are observed.

Related publications:

1. McKinlay, JB and CS Harwood. 2010. Carbon dioxide fixation as a central redox cofactor recycling mechanism in bacteria. Proceedings of the National Academy of Sciences USA. 107 (26): 11669-11675.
2. McKinlay, JB and CS Harwood. 2010. Mini-review. Photobiological production of hydrogen gas as a biofuel. Current Opinion in Biotechnology. 21 (3): 244-251.
3. Huang, JJ, EK Heiniger, JB McKinlay, and CS Harwood. 2010. Production of hydrogen gas from light and the inorganic electron donor thiosulfate by Rhodopseudomonas palustris. Applied and Environmental Microbiology. 76 (23): 7717-7722.