Noooo not at all that's just bad for the environment
Yellow-indicates acid production from fermentation of the carbohydrate lower the pH below the neutral range
The 3rd one I think not really sure
Just say we have a big amount of tryptophan in the sense that it exceeds, tryptophan would act as a co-repressor which prevents synthesis of more enzymes for its production
Hope this helps :)
The second one I believe.
