Distinguished Lectureship in Nanoscience

Biology plays a major role in the carbon cycle on earth. It was estimated that terrestrial photosynthesis draws down 120 giga tons of carbon per year, half of which is released back to the atmosphere by respiration. The remaining carbon is slowly converted to CO2 and CH4 due to microbial metabolism, with about 10% stored in soil. To date, burning of fossil fuel emits more than 10 gigatons of carbon annually, which upsets the natural balance of the carbon cycle and caused a rapid increase of atmospheric greenhouse gas (GHG) in recent years. With advances in biochemistry, biophysics, molecular biology and cell biology, it has become possible to design new metabolism with an aim for reducing GHG in the atmosphere. However, because of the complexity, metabolic phenotypes cannot be predicted to the desirable precision, directed cell evolution thus becomes an important approach to constructing new metabolism. Here we will present examples of how design and evolution can be used to explore new metabolism in the cell. We will use  β-alanine synthesis to illustrate the emergence of new metabolic pathways, and discuss CO2 and methanol assimilation in E. coli, cyanobacteria, and cell-free systems.