Revealing novel synergistic defense and acid tolerant performance of Escherichia coli in response to organic acid stimulation

Galactitol Transport Factor GatA Relieves ATP Supply Restriction to Enhance Acid Tolerance of Escherichia coli in the Two-Stage Fermentation Production of D-Lactate

“…After 4 h of incubation, the pH value that decreases the cell viability by 6 orders of magnitude (from 10 6 to 10 0 ) could obviously reflect the variability of cells [27,29]. In this study, we follow the previous pH setup value 4.0 of D-LA lethal stress medium [25,26]. When cells at mid-log growth were reacquired and transferred to D-LA lethal stress medium (pH 4.0), the number of viable cells decreased rapidly.…”

“…Intracellular pH was measured fluorescently using 2 ,7 -bis(2-carboxyethyl)-5(and 6)-carboxyfluorescein acetoxymethyl ester (BCECF AM, Beyotime Biotechnology, Shanghai, China) as a fluorescent probe. Three mL of cells cultured under different conditions were harvested by centrifugation at 7000× g for 3 min and washed three times with 50 mM HEPES-K (Sigma-Aldrich, Shanghai, China) buffer (pH 8.0) [25]. The cell precipitate was resuspended in 3 mL of the same buffer and 1 µL of BCECF AM was added and mixed in a water bath at 30 • C for 20 min.…”

“…Candidate proteins with the potential to enhance lactic acid tolerance in E. coli were identified by comparing transcriptomic data before and after evolution under D-LA lethal stress [25]. From this analysis, gatA was regarded as a candidate acid-tolerant functional factor that enhances E. coli lactate tolerance.…”

“…The aim of this study was to develop an effective strategy that promotes tolerance to a wide range of organic acids in E. coli, and increases the ability to produce organic acids without affecting normal cellular metabolism. In a previous study, we used an adaptive evolutionary strategy to obtain an evolved strain of E. coli DLA3, with an increased tolerance to D-LA from 3.4 g•L −1 to 4.2 g•L −1 [25]. We compared the differences in transcript levels between DLA3 and the parental strain E. coli MG1655 before and after D-LA lethal stress, and found that the transporter factor GatA, which acts in the transmembrane transport metabolic pathway of galactitol has potential as a universal anti-acid component.…”

Rationally Engineering pH Adaptation of Acid‐Induced Arginine Decarboxylase from Escherichia coli to Alkaline Environments to Efficiently Biosynthesize Putrescine

“…In neutral and alkaline conditions, the activity of AdiA will be inhibited for its presence as a dimer or monomer. [ 12 , 13 , 14 ] This pH inhibition effect is detrimental to the biosynthesis of alkaline putrescine in whole‐cell systems. In addition, lysine decarboxylases CadA, another important member in the acid stress response system, possesses a pH‐regulated mechanism for the oligomerization of bilayer cyclic decamers similar to that of AdiA.…”