I call this theory the Greening of Mars.

If I'm going to create a false atmosphere on MARS, by genetically engineering a lichen to live in an extremophile environment, then I have to look for desirable genes at the bottom of the ocean.

I need to take the "hardiness genes" from the bacteria that is most genetically similar to the green alga or cyanobacterium. This gene has to come from the bottom of the ocean. So, take that gene (it probably has something to do with metabolizing nitrogen, but that's another story) and incorporate it into the lichen's genome to make it super hardy, so hardy it can live on the surface of Mars with minimal "fuss" and if I play my cards right, the lichen will hence produce large concentrations of oxygen over time. I have to travel to the bottom of the ocean to "green" Mars.

In the end, the change in the concentrations of gases in the atmosphere would never make the air breathable? In my current opinion, it would just make it possible for material science to make a space suit that would be lighter, more comfortable, etc?

I like to pretend like I could do it all myself. OH WAIT, I could. I only need other people's money, other people just get in the way.