title: Sodium ions activated phosphofructokinase leading to enhanced D-lactic acid production by Sporolactobacillus inulinus using sodium hydroxide as a neutralizing agent.
abstract: Sporolactobacillus inulinus is a superior D-lactic acid-producing bacterium and proposed species for industrial production. The major pathway for D-lactic acid biosynthesis, glycolysis, is mainly regulated via the two irreversible steps catalyzed by the allosteric enzymes, phosphofructokinase (PFK) and pyruvate kinase. The activity level of PFK was significantly consistent with the cell growth and D-lactic acid production, indicating its vital role in control and regulation of glycolysis. In this study, the ATP-dependent PFK from S. inulinus was expressed in Escherichia coli and purified to homogeneity. The PFK was allosterically activated by both GDP and ADP and inhibited by phosphoenolpyruvate; the addition of activators could partly relieve the inhibition by phosphoenolpyruvate. Furthermore, monovalent cations could enhance the activity, and Na+was the most efficient one. Considering this kind activation, NaOH was investigated as the neutralizer instead of the traditional neutralizer CaCO3. In the early growth stage, the significant accelerated glucose consumption was achieved in the NaOH case probably for the enhanced activity of Na+-activated PFK. Using NaOH as the neutralizer at pH 6.5, the fermentation time was greatly shortened about 22 h; simultaneously, the glucose consumption rate and the D-lactic acid productivity were increased by 34 and 17%, respectively. This probably contributed to the increased pH and Na+-promoted activity of PFK. Thus, fermentations by S. inulinus using the NaOH neutralizer provide a green and highly efficient D-lactic acid production with easy subsequent purification.
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, Jiangsu, 211816, China.|State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu, 210008, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Zheng
authors.affiliation: Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection of China, Nanjing, Jiangsu, 210042, China.
authors.forename: Mingqing
authors.initials: M
authors.lastname: Liu
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, Jiangsu, 211816, China.
authors.forename: Jiaduo
authors.initials: J
authors.lastname: Sun
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, Jiangsu, 211816, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Wu
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, Jiangsu, 211816, China. bingfanghe@njtech.edu.cn.|School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, Jiangsu, 211816, China. bingfanghe@njtech.edu.cn.
authors.forename: Bingfang
authors.initials: B
authors.lastname: He
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D056449:Bacillales / Q000201:enzymology* / Q000235:genetics; D002412:Cations / Q000378:metabolism; D003001:Cloning, Molecular; D020536:Enzyme Activators / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006153:Guanosine Diphosphate / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism*; D010728:Phosphoenolpyruvate / Q000378:metabolism; D025221:Phosphofructokinases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012972:Sodium Hydroxide / Q000378:metabolism*
chemical_list: D002412:Cations; D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; D006153:Guanosine Diphosphate; D019344:Lactic Acid; D012972:Sodium Hydroxide; D000244:Adenosine Diphosphate; D010728:Phosphoenolpyruvate; D025221:Phosphofructokinases
keywords: Allosteric regulation; D-Lactic acid production; Neutralizer; Phosphofructokinase; Sodium ions; Sporolactobacillus inulinus