Effect Of Pyruvic Acid On Bacterial Cellulose Synthesis Of Gluconacetobacter Xylinus CGMCC 2955

Due to the excellent properties of bacterial cellulose,it has important application value in many fields.There are many reports on the synthesis and production of bacterial cellulose,but there are still many unknown issues to be explored in the relevant regulatory mechanisms.Therefore,it is of great significance to further study how to regulate the synthesis of bacterial cellulose to improve the production of bacterial cellulose.Pyruvic acid is a key intermediate metabolite in the process of carbohydrate metabolism,linking the Embden-Meyerhof-Parmas pathway(EMP)and the tricarboxylic acid cycle(TCA).In this study,pyruvic acid was added to two different media and G.xylinus was cultured under static condition.This study investigated the effect of pyruvic acid on the synthesis of bacterial by comparing the fermentation properties of G.xylinus,the key enzyme of carbon metabolism and the intracellular metabolites,in order to provide basic data for improving and regulating bacterial cellulose biosynthesis.When cultured in semi-synthetic medium,the addition of pyruvic acid to the medium promoted the growth of G.xylinus cells,and the bacterial cellulose production increased by 21%when cultured for 15 days.The activities of key enzymes in the EMP pathway were reduced during the cultivation process.The activities of isocitrate dehydrogenase and succinate dehydrogenase in the TCA cycle were increased.The UGPase activity in the bacterial cellulose synthesis pathway was increased.In addition,the metabolic flux of the intracellular pentose phosphate pathway(PPP)to the nucleic acid metabolic pathway of G.xylinus was reduced during the logarithmic phase.The amino acid metabolism associated with the TCA cycle was affected during the fermentation.In the stationary phase,the catabolism of saturated fatty acids was increased.It showed that after the addition of pyruvic acid,the metabolism of the glucose branch weakens in the logarithmic phase,more glucose flows to the bacterial cellulose synthesis pathway,and the yield of bacterial cellulose was increased.In addition,the energy metabolism of the intracellular fatty acids in G.xylinus was enhanced during the stationary phase.The growth of the bacteria provided more energy,so the amount of G.xylinus cells increased.When cultured in synthetic medium,with the addition of pyruvic acid,the glucose utilization of G.xylinus was increased and the cell growth rate was promoted.The production of bacterial cellulose was improved by 33%when cultured for 13 days.The activity of pyruvate kinase in the EMP pathway was reduced.And the activity of isocitrate dehydrogenase and succinate dehydrogenase in the TCA cycle was significantly increased in the early logarithmic phase.The UGPase activity was also significantly increased.Through the analysis of intracellular metabolites of G.xylinus,the metabolic pathway of bacterial cellulose synthesis was enhanced,and the amino acid branch metabolism associated with the TCA cycle was enhanced.After adding pyruvic acid,the increase of TCA cycle and related amino acid metabolism provided more energy for cell growth to reduce the energy metabolism of grape vines.Therefore,more glucose was used for bacterial cellulose synthesis,and the yield of bacterial cellulose was increased.In both semi-synthetic and synthetic media culture conditions,the addition of pyruvic acid caused a certain influence on the intracellular energy metabolism and the synthetic pathway of bacterial cellulose.However,the metabolism regulation of G.xylinus was different after the addition of pyruvic acid,because its own growth and metabolism were different.Compared with the control group,when the pyruvic acid were added,there was no significant difference in the microscopic morphology,chemical bonds,crystallinity,thermal stability and the Young's modulus of the bacterial cellulose.However,the tensile strength was increased by 30%.