As much as I like Interstellar, the movie could have spend more tiime to try to get some of the details about biology right, including trying to work out its blight so it worked a little better. The viewer is supposed to believe that whatever the blight is, it is reducing the oxygen in the air within several human generations. While early bacteria did cause a similar atmospheric change on the early Earth when they evolved to perform photosynthesis, it took place over millions of years and not a few generations. It's a darn good thing they did, too, because these early bacteria started releasing free oxygen into the atmosphere.
I have learned a new rule in this house. When a movie has an obvious flaw in physics, I am supposed to listen with intent interest while my roommate, who has a bachelor's in physics, breaks down the problems with the physicis in excruiciating detail. If I find out that a movie that has excellent physics but poor biology, I am supposed to be quiet about these scientific errors and not explain them to her in excruciating detail.