Metabolic and Process Engineering of Clostridium beijerinckii for Butyl Acetate Production in One Step

n-Butyl acetate is an important food additive
commonly produced via concentrated sulfuric acid
catalysis or immobilized lipase catalysis of butanol and acetic acid.
Compared with chemical methods, an enzymatic approach is more environmentally
friendly; however, it incurs a higher cost due to lipase production. In vivo biosynthesis via metabolic engineering
offers an alternative to produce n-butyl acetate.
This alternative combines substrate production (butanol and acetyl-coenzyme
A (acetyl-CoA)), alcohol acyltransferase expression, and esterification
reaction in one reactor. The alcohol acyltransferase gene ATF1 from Saccharomyces cerevisiae was introduced into Clostridium beijerinckii NCIMB 8052, enabling it
to directly produce n-butyl acetate from glucose
without lipase addition. Extractants were compared and adapted to
realize glucose fermentation with in situ n-butyl acetate extraction. Finally, 5.57 g/L of butyl acetate
was produced from 38.2 g/L of glucose within 48 h, which is 665-fold
higher than that reported previously. This demonstrated the potential
of such a metabolic approach to produce n-butyl acetate
from biomass.