Construction Of The Best Actobacter Aceti And Preliminary Study On Vinegar Fermentation

Vinegar is a traditional oriental grain food with a sour taste and distinct fragrance which is used as a condiment sauce worldwide. The vinegar fermentation includes liquid fermentation and solid-state fermentation and so on. The liquid fermentation time is shorter than solid-state fermentation, so the organic acid fermentation was not sufficient. Whole-cell biocatalysts are commonly limited by low tolerance of extreme process conditions such as alcoholic strength, temperature, pH, and concentration of solute and one of the most significant influences is alcohol concentration. Here we describe the use of genome shuffling to improve the ethanol tolerance of a poorly characterized industrial strain of acetic acid bacterium.In this study, the acetic acid bacteridum strain, Acetobacter sp. was separated and isolated form vinegar grains which was obtained from the factory. It was treated with UV and Hydroxylamine hydrochloride.The starting mutant population of genome shuffling was obtained after selecting by high ethanol plates. The mutant strains were constructed after three rounds of shuffling. The strain A3-11was then selected by media with high content of ethanol. The ethanol tolerance of A3-11was increased from7%to13%.In high-ethanol liquid medium, A3-11well grew and validly utilized ethanol. It had log-phase faster than the control strain (the wild type strain). During the vinegar fermentation, the content of total acid component produced by the strain A3-11was distinctly improved compared with the control. The results of liquid chromatography showed that the content of the main organic acid components was improved after adding A3-11. Acetic acid was produced twice as much as the wild type strain. Furthermore, the concentration of butanedioic acid was4.04-fold greater than the control. Another important organic acid compound malic acid was enhanced by up to2.97times higher than the control. In the fermentation, total acid produced by A3-11was increased from14.89%to34.22%; total acetate produced by A3-11was increased from24.39%to32.46%.