Disclosed herein are bacteria engineered to treat diseases associated with hyperammonemia and methods of use thereof. Specifically, the bacteria are engineered to comprise a racemase to enable the detection of non-naturally occurring metabolites as an indication that the engineered bacteria are effectively converting ammonia.

Provided herein are compositions and methods for stabilizing enzymes. Also provided are systems, compositions and methods for using the stabilized enzymes to produce a desired compound.

Disclosed herein are a microorganism with excellent deacetoxycephalosporin C (DAOC) productivity and a use thereof. A mutant microorganism with improved DAOC productivity and a use thereof for producing 7-aminodeacetoxycephalosporanic acid (7-ADCA) are provided.