Ester-Producing Mechanism of Ethanol O-acyltransferase Gene in from Shanxi Aged Vinegar.

The ethanol O-acyltransferase is an important element of key signaling pathways and is widely expressed in yeast strains. In this study, we investigated the expression of 1 in the overexpression lines or knockout system of using qRT-PCR and western blotting. The amount of total protein was determined using the Bradford method; the esterase activity was determined using p-nitrophenyl acetate as a substrate, and the production of volatile fatty acids in wild-type, knockout, and over-expression systems was detected using SPME GC-MS. The esterase activity of 1-knockout was significantly lower than that in wild type (<0.01), and the activities of esterase in three 1-overexpressing strains-OE-1, OE-2, and OE-3-were significantly higher than those in wild type (<0.01). In the 1-knockout strain products, the contents of nine volatile fatty acids were significantly lower than those in wild type (<0.01), and the relative percentages of three fatty acids, methyl nonanoate, methyl decanoate, and ethyl caprate, were significantly lower than those in the other six species in the wild-type and knockout groups (<0.05). The nine volatile fatty acids in the fermentation products of the overexpressed 1 gene were significantly higher than those in the wild-type group (<0.01). The relative percentages of the three fatty acid esters, methyl nonanoate, methyl caprate, and ethyl caprate, were significantly higher than those in the other six species (<0.05). 1 plays an important regulatory role in esterase activity and the production of medium-chain volatile fatty acids.