Efficient, Simple Production of Corresponding Alcohols from Supplemented C2-C8 Carboxylic Acids in Escherichia coli Using Acyl-CoA Transferase from Megasphaera hexanoica

Abstract

The accumulation of short-chain carboxylic acids (SCCAs), such as acetic acid (C-2), propionic acid (C-3), butyric acid (C-4), and valeric acid (C-5), produced by acetogens in the anaerobic digestion (AD) process hampers the maintenance of stable AD processes in biomethane production. The conversion of various SCCAs to the corresponding alcohols can be a good solution not only for utilizing abandoned or harmful SCCAs and producing useful alcohols but also for increasing the efficiency of the biogas production process. ACT01_02765 (acyl-CoA transferase) fromMegasphaera hexanoicaquickly and easily converted C-2-C(8)carboxylic acids into the corresponding alcohols inEscherichia coliwith AdhE2 (alcohol dehydrogenase) fromClostridium acetobutylicum. E. coli(ACT01_02765 and AdhE2) converted carboxylic acids to the corresponding alcohols with a conversion yield that was approximately 40 times higher and a conversion rate that was approximately 10-50 times faster than those ofE. coli(Ptb-Buk and AdhE2). The enzymatic machinery inE. coli(ACT01_02765 and AdhE2) is effective for carboxylic acids of different carbon chain lengths, resulting in the production of propanol, butanol, pentanol, hexanol, heptanol, and octanol.