Fig. 2
From: Microbial production of butyl butyrate: from single strain to cognate consortium
Combinatorial approaches attempted in single strain for BB biosynthesis. Black color denotes the native pathways responsible for butyryl-CoA and/or butanol accumulation through intracellular acyl-CoA molecules (in Clostridia species). The grey color shows the pathway optimizations by either overexpressing downstream acyl-CoA enzymes or introducing new enzymes with higher activity. Green color indicates the heterologous pathways aiming at improving the intracellular butyryl-CoA molecule for high butyrate and butanol availability (often in E. coli). In some cases, butyryl-CoA and/or butanol are supplemented in the fermentation system. The blue circles indicate BB produced. AAT modules should be introduced to catalyze the esterification reaction of butyryl-CoA with butanol into biosynthetic BB. adhE2 (aldehyde/alcohol dehydrogenase)