I should have said fermentation, not sugar.
"In a number of cases, a synthetically produced amino acid can be biologically transformed into another amino acid by a semi-fermentation or an enzymatic process. The semifermentation process involves the metabolic interaction of a fermentation organism with a synthetic precursor. An increasing number of organisms are genetically engineered. Amino acids may also be formed by reactions catalyzed by enzymes. The substrates may be naturally occurring, but they may also be synthetic, and are often both. They may also be produced by a wide number of non-biological processes that are considered to be synthetic by the TAP (Areki and Ozeki, 1991)."
This is discussing the breakdown of synthetic nutes.