Metabolic engineering of Clostridium acetobutylicum for the production of butyl butyrate
Butyl butyrate is widely used as a fragrance additive for foods and beverages. The first step in the currently used process is the production of precursors, including butanol and butyrate, from petroleum using chemical catalysts, followed by the conversion of precursors to butyl butyrate by immobilized lipase. In this work, we engineered Clostridium acetobutylicum for the selective, one-step production of butyl butyrate from glucose. C. acetobutylicum ATCC 824, possessing a strong carbon flux that yields butanol and butyryl-CoA, was selected as a host and was engineered by introducing alcohol acyltransferases (AATs) from Fragaria x ananassa (strawberry) or Malus sp. (apple). Batch culture of the engineered C. acetobutylicum strain CaSAAT expressing the strawberry SAAT gene produced 50.07 mg/L of butyl butyrate with a selectivity of 84.8% of total esters produced. Also, the engineered C. acetobutylicum strain CaAAAT expressing the apple AAAT gene produced 40.60 mg/L of butyl butyrate with a selectivity of 87.4%. This study demonstrated the feasibility of the one-step fermentation of butyl butyrate from glucose in the engineered C. acetobutylicum, as a proof of concept.
KeywordsButyl butyrate Clostridium acetobutylicum Alcohol acyltransferase Butanol Ester
This work was supported by a grant from the Ministry of Science and ICT (MSIT) through the National Research Foundation (NRF) of Korea (NRF-2016R1D1A3B04933184). SYL was supported by the Technology Development Program to Solve Climate Changes on Systems Metabolic Engineering for Biorefineries from the MSIT through the NRF of Korea (NRF-2012M1A2A2026556 and NRF-2012M1A2A2026557).
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Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals by any of the authors.
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