More atmosphere means more molecules to scatter the violet and blue light away from your eyes. If the path is long enough, all of the blue and violet light scatters out of your line of sight. The other colors continue on their way to your eyes. This is why sunsets are often yellow, orange, and red.”
The alkaline/alkaline results could indicate that only the protein was utilized by the organism, but it could also be a result of prolonged incubation. The organisms could have exhausted that available sugar and then reverted to protein catabolism.