Efficient, Simple Production of Corresponding Alcohols from Supplemented C_2-C_8 Carboxylic Acids in Escherichia coli Using Acyl-CoA Transferase from Megasphaera hexanoica

摘要

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) from Megasphaera hexanoica quickly and easily converted C_2-C_8 carboxylic acids into the corresponding alcohols in Escherichia coli with AdhE2 (alcohol dehydrogenase) from Clostridium 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 of E. coli (Ptb-Buk and AdhE2). The enzymatic machinery in E.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.