Improving the Acetic Acid Fermentation of Acetobacter pasteurianus by Enhancing the Energy Metabolism.

Xinyu Wang,Jun Wang,Zhiwei Feng,Hang Zhao,Jia Song,Yu Zheng,Min Wang,Weizhao Li,Tao Hu,Zhi Lei

doi:10.3389/fbioe.2022.815614

Abstract

Energy metabolism is important for cell growth and tolerance against environment stress. In acetic acid fermentation by Acetobacter pasteurianus, the correlation coefficients of acid production rate with energy charge and ATP content were 0.9981 and 0.9826, respectively. The main energy metabolism pathway, including glycolysis pathway, TCA cycle, ethanol oxidation, pentose phosphate pathway, and ATP production, was constructed by transcriptome analysis. The effects of fermentation conditions, including dissolved oxygen, initial acetic acid concentration, and total concentration, on acetic acid fermentation and energy metabolism of A. pasteurianus were analyzed by using the RT-PCR method. The results showed the high energy charge inhibited glucose catabolism, and associated with the high ethanol oxidation rate. Consequently, a virtuous circle of increased ethanol oxidation, increased energy generation, and acetic acid tolerance was important for improving acetic acid fermentation.

Highlights

Acetic acid is an important food material fermented from ethanol by using acetic acid bacteria (AAB) (Saichana et al, 2015)
This work aimed to reveal the relationship between ethanol oxidation and energy generation of A. pasteurianus, and to improve the acetic acid fermentation according to the energy metabolism
The experimental data for the specific rate (SR) of acetic acid production, ethanol consumption, or glucose consumption could be calculated with the following formula: SR dc dt Xt where, SR is the specific rate of acetic acid production, ethanol consumption, or glucose consumption. dc/dt presents the rate of acetic acid production, ethanol consumption, or glucose consumption

Summary

Introduction

Acetic acid is an important food material fermented from ethanol by using acetic acid bacteria (AAB) (Saichana et al, 2015). Several mechanisms reportedly help AAB resist acetic acid stress, relating to (I) PQQ-ADH (Trcek et al, 2006; Yakushi et al, 2018), (I) TCA cycle (Andrés-Barrao et al, 2012; Andrés-Barrao et al, 2016), (III) ATP binding cassette transporter, such as AatA (Nakano et al, 2006), (IV) amino acid metabolism (Yin et al, 2017), and (V) adaptive response of tolerant proteins (Ishikawa et al, 2010). All these mechanisms are related to energy metabolism or ATP. Combined with the ethanol respiration chain, intracellular H+ is pumped to the outside of the membrane, forming a proton gradient, which promotes adenosine triphosphatase (ATPase) to produce ATP for cell growth and metabolism

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