A certain bacterium that is a tryptophan auxotroph was observed to grow well when it was supplied wi… Show more A certain bacterium that is a tryptophan auxotroph was observed to grow well when it was supplied with tryptophan, but as soon as the tryptophan in the environment was exhausted, the bacteria started to excrete a metabolite on the tryptophan biosynthetic pathway. why didn’t the bacteria excrete the metabolite before exhausting the environmental tryptophan. • Show less