What is pioneer organisms?
Pioneer organisms, also called pioneer species, are hardy species which are the first to colonize a completely undeveloped environment, beginning a chain of ecological succession that ultimately leads to a biodiverse steady-state ecosystem. For instance, for an environment where there is no life, some lichens may be the first life form of this environment. After their metabolism breaking down inorganic rocks into organic soil, other plants will take advantages from those organic substances to grow, and the biodiversity of this ecosystem will increase.
What is the prototype of our project?
The prototype of E. pangu is oxygenic microalgae, the pioneer organism of earth. (Fig. 1)For primitive earth, the atmosphere had almost no gaseous O2, which is critical to the emergence of other organisms. It was because the emergence of all kinds of oxygenic microalgae such as cyanobacteria that changed the atmosphere of earth to fit other organisms on the earth. Likewise, for Martian atmosphere, gaseous oxygen is very rare, and the main component is CO2, which account for almost 95% of Martian atmosphere. Thus, we thought that Martian pioneer organism should be capable of fixing excessive CO2, and also some N2, the third main component of Martian atmosphere.
Fig. 1. Oxygenic microalgae grow on medium with out carbon source.
Why E. pangu is better pioneer organism than microalgae for Mars?
Although both cyanobacteria and E. pangu are capable of carbon fixation, but there is an obvious advantage for E. pangu : The energy used to fix carbon in E. pangu is chemical energy, while in cyanobacteria, the energy comes from light. It is remarkable that the Martian atmosphere is rarer than that of earth, which means cyanobacteria can not use the solar light energy directly because of UV radiation. For E. pangu , they can be set in dark environment so that we do not need to waste time on solving the problem of UV radiation.
Why we call our engineered E.coli E. pangu ?
In Chinese mythology, Pangu is the creator of universe. The emergence of other organisms was impossible without Pangu. Thus, as the first "life form"; of the universe, Pangu can be considered as the pioneer organism of the whole universe. Combined Chinese mythology with our project, our engineered bacteria are called E. pangu .