Microbes are often identified using biochemical tests that detect specific enzymes of metabolic pathways. e. coli typically ferments lactose, whereas shigella does not. if a pure culture of each bacterium was placed in a tube containing lactose as the only food source, and a chemical indicator changed color after a ph change, what would the tubes look like after the bacteria were incubated?

a. both tubes would show the evidence of lactose fermentation by turning alkaline.
b. the tube with e. coli would indicate a ph change, and the shigella tube would indicate no change.
c. neither tube will show any change.
d. both tubes would show the evidence of lactose fermentation by turning acidic and changing the ph indicator.

b. The tube with E. coli would indicate a pH change, and the Shigella tube would indicate no change.

Explanation:

Since E. coli has the ability to ferment lactose, one of the products of fermentation is lactic acid. Formation of acid from fermentation will cause a color change in the indicator as a result of pH change.

In summary, the pH of the tube with E. coli is expected to indicate a change after incubation while that of Shigella without the ability to ferment lactose will indicate no change.

The correct option is b.

a axis of a graph is a color or shade so we can all go outside and have a party so we can eat   some grilled cheese sammiches and broccoli and have some ugly fun times

i don't know why i put this, i know its not the i was just bored : p

delete this answer while you can