Expert: Walter Hintz - 3/30/2009

Question
Hi:

I've heard that bacteria can easily digest and metabolize carbohydrates and proteins but cannot metabolize lipids. If this is true, then can bacteria be used to breakdown all the carbs and proteins in the milk [which pretty much constitute most of the non-fat milk solids] to make the butter? Once the proteins and carbs are metabolized by the bacteria, they will no longer be in the hard solid form the originally were in. For example, casein [the chief milk protein] is solid, however, once bacteria break it down, they will convert it to amines, ammonia, propionic acids and other volatile compounds -- some maybe solid but very soft and not take up as much space as the original casein.

I'm guessing if all of the above happens, then the end result will resemble butter. Right?


Thanks,

Green

Answer
There are species of bacteria that can metabolize anything including inorganic compounds (sulfur bacteria).  E. coli can reduce lipids in the intestines.  I am not acquainted with milk chemistry enough however to consider the conversion of milk to butter.