Microbial production of butyl butyrate, a flavor and fragrance compound.

Butyl butyrate (BB) has been widely used as a flavor and fragrance compound in the beverage, food, perfume, and cosmetic industries. Currently, BB is produced through two-step processes; butanol and butyrate are first produced and are used as precursors for the esterification reactions to yield BB in the next step. Recently, an alternative process to the current process has been developed by using microorganisms for the one-pot BB production. In the one-pot BB process, alcohol acyl transferases (AATs) and lipases play roles in the esterification of butanol together with their co-substrates butyryl-CoA and butyrate, respectively. In this paper, we review the characteristics of two enzymes including AAT and lipase in the esterification reaction. Also, we review the one-pot processes for BB production by employing the wild-type and engineered Clostridium species and the engineered Escherichia coli strains, with the combination of AATs and lipases.