title: Systems-level understanding of how Propionibacterium acidipropionici respond to propionic acid stress at the microenvironment levels: mechanism and application.
abstract: In previous work, three evolved Propionibacterium acidipropionici mutants with higher tolerant capacity of propionic acid (PA) were obtained by genome shuffling. Here, we attempted to unravel the acid-tolerant mechanism of P. acidipropionici by comparing the physiological changes between P. acidipropionici and three mutants. The parameters used for comparison included intracellular pH (pHi), NAD⁺/NADH ratio, H⁺-ATPase activity, and the intracellular amino acids concentrations. It was indicated that the acid tolerance of P. acidipropionici was systematically regulated. Specifically, low pHi promoted the P. acidipropionici to biosynthesize more H⁺-ATPase to pump the protons out of the cells, and as a result, the NAD⁺/NADH ratio increased due to the decreased protons concentration. The increased arginine, aspartic acid, and glutamic acid concentrations helped to resist the acidic environment by consuming more H⁺ and generating more ATP and NH₃. Based on what was analyzed above, 20 mM arginine and aspartic acid were added during the shaker culture of P. acidipropionici, and the maximal PA titer reached 14.38 g/L, which was increased by 39.9% compared with the control.
authors.affiliation: Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China.
authors.forename: Ningzi
authors.initials: N
authors.lastname: Guan
authors.forename: Long
authors.initials: L
authors.lastname: Liu
authors.forename: Hyun-Dong
authors.initials: HD
authors.lastname: Shin
authors.forename: Rachel R
authors.initials: RR
authors.lastname: Chen
authors.forename: Juan
authors.initials: J
authors.lastname: Zhang
authors.forename: Jianghua
authors.initials: J
authors.lastname: Li
authors.forename: Guocheng
authors.initials: G
authors.lastname: Du
authors.forename: Zhongping
authors.initials: Z
authors.lastname: Shi
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D009154:Mutation; D009243:NAD / Q000378:metabolism; D011422:Propionates / Q000494:pharmacology*; D011424:Propionibacterium / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D000596:Amino Acids; D011422:Propionates; D009243:NAD; D006180:Proton-Translocating ATPases; C029658:propionic acid
keywords: Acid tolerance; Genome shuffling; Microenvironment; Propionibacterium acidipropionici; Propionic acid