Journal
JOURNAL OF BIOTECHNOLOGY
Volume 167, Issue 1, Pages 56-63Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jbiotec.2013.06.008
Keywords
Propionibacterium acidipropionici; Genome shuffling; Acid tolerance; Microenvironment; Propionic acid
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Funding
- National Natural Science Foundation of China [21006040]
- 973 Program [2012CB720806, 2013CB733902]
- 111 Project [111-2-06]
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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 (pH(i)), 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 pH(i), 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, 20mM 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. (C) 2013 Elsevier B.V. All rights reserved.
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