Study On The Relationship Between Energy Charge Of Acetobacter Pasteurianus And Acetic Acid Fermentation

Acetic acid is commonly produced by fermentation,which is an important raw material for the food industry.As an indicator to measure energy state of bacteria,energy charge is closely related to acetic acid fermentation,The acid-resistant mechanism of Acetobacer pasteurianus is also closely related to energy metabolism.The main energy metabolism pathway of Acetobacter pasteurens was constructed during acetic acid fermentation by transcriptome.And initial acid,dissolved oxygen,total concentration and other fermentation conditions as well as the effect of enhanced ethanol respiratory chain were particular analyzed on Acetobacter pasteurensis energy metabolism and acetic acid fermentation.Transcriptome of Acetobacter pasteurensis during acetic acid fermentation was analyzed,and 474 genes was enriched.The KEGG matched metabolic pathways are mainly involved in the nucleosome metabolism,glucose metabolism,tolerance mechanism,energy metabolism,and carbon metabolism of Acetobacter pasteurensis.The energy metabolism pathway of Acetobacter pasteurensis AC2005 was constructed,including glycolytic pathway,TCA cycle,ethanol oxidation,pentose phosphate pathway,ATP production and acid resistance genes.The relationship between acetic acid fermentation energy and bacterial metabolic activity and acetic acid fermentation efficiency was analyzed.The results showed that under different initial acid conditions,the acid production rate was the highest at the concentration of 40 g/L bottom acid,which was 2.02 g/L/h.The energy load is consistent with the change trend of ATP concentration.In the early stage of fermentation,glucose is the main substrate.and 35 g/L of the initial acid concentration consumes the most glucose and the highest productivity.And the metabolism-related TCA cycle weaken,the ATP metabolism reduced,and the acid-resistance up-regulated gene expression because of the increase of the concentration of the initial acid.Entering the period of rapid acid production,ethanol has become a major substrate,with decreasing of glucose consumption,increasing of ATP and energy load,and accelerating of acid production rate.At the same time,the TCA cycle was attenuated due to the up-regulation of ethanol respiratory chain-related genes and the up-regulation of ATP production.This indicates that the substrate concentration affects the energy metabolism of the cells,as well as the production of ATP and the tolerance of the cells.Under different dissolved oxygen conditions,the acid production rate of 20%dissolved oxygen was the highest,which was 2.00 g/L/h.The energy load is consistent with the change trend of ATP concentration.In the early stage of fermentation,glucose is the main production substrate,and 10%of dissolved oxygen consumes the least amount of glucose and the least production.There was no significant difference between 20%and 30%of dissolved oxygen consumption of glucose.The increase of dissolved oxygen increased the expression of TCA cycle related to the metabolism of bacteria,enhanced ATP metabolism,and increased the expression of acid-resistant genes.Entering the period of rapid acid production,ethanol has become a major productivity substrate,with reduced glucose consumption,increased ATP and energy load,and accelerated acid production rate.At the same time,the up-regulation of ethanol respiratory chain-related genes and the up-regulation of ATP production have attenuated the TCA cycle,and acid-resistant genes Increased expression of base acid increased.It shows that dissolved oxygen affects the energy metabolism of the bacteria,as well as the production of ATP and tolerance of the bacteria.At different total concentrations,the acid production rate was the highest at a total concentration of 10%,which was 2.11 g/L/h.The energy load is consistent with the change trend of ATP concentration.In the early stage of fermentation,glucose is the main production substrate,and 9%of the total concentration consumes the most glucose and the highest productivity.And the increase of total concentration weakened TCA cycle associated with bacterial metabolism,decreased ATP metabolism,and up-regulated acid-resistant gene expression.Entering the period of rapid acid production,ethanol has become a major productivity substrate,with reduced glucose consumption,increased ATP and energy load,and accelerated acid production rate.At the same time,the up-regulation of ethanol respiratory chain-related genes and the up-regulation of ATP production have attenuated the TCA cycle,and acid-resistant genes Increased expression of base acid increased.This indicates that the substrate concentration affects the energy metabolism of the cells,as well as the production of ATP and the tolerance of the cells.The effect of enhanced ethanol respiration chain on acetic acid fermentation and energy load was analyzed.The results showed that the enhanced ethanol respiratory chain at the early fermentation stage had no significant effect on the metabolic activity of the bacteria,and entered the rapid acid production period,which enhanced the expression of ethanol oxidation-related genes in the ethanol respiratory chain recombinant strain.At the same time,TCA cycle expression was up-regulated and ATP production was up-regulated,indicating that the enhanced ethanol respiratory chain can enhance energy metabolism and ATP production,thereby increasing bacterial metabolic activity.