You have a tube of nutrient broth, in which E. coli is growing. Upon analyzing the broth chemistry, you find: oxygen content has dropped a bit, but carbon dioxide has gone up a lot formic, acetic, and lactic acids are present What kind of metabolism has most likely occurred

Explanation:

A metabolic process in which an organism breaks down glucose to produce carbon dioxide and ATP in absence of oxygen.Other than carbon dioxide and  ATP fermentation produces lactic acid, ethyl alcohol etc.

A drop in oxygen concentration and rise in Carbon dioxide levels with the presence of Formic ,acetic and lactic acid signifies that the metabolism which has occurred is Fermentation.