To convert 2-KIV to isobutyraldehyde, a 2-Kivd enzyme is used. The Kivd enzyme from L. lactis is an uncommon enzyme with a traditional industrial role of aldehyde production for aroma development in cheese [75]. Given its activity with branched chain ketoacid substrates, this enzyme is uniquely suited to the task of bridging the BCAA production pathway to Adh to allow for heterologous IBT production [33]. The enzyme is a non-oxidative, thiamine diphosphate dependent, Mg2+-dependent keto acid decarboxylase [75]. The kivd gene can be expressed in an active form in R. eutropha (Sinskey laboratory, data not shown).