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Appl Biochem Biotechnol. 2015 Dec;177(7):1508-19. doi: 10.1007/s12010-015-1831-8. Epub 2015 Oct 19.

Study of metabolic profile of Rhizopus oryzae to enhance fumaric acid production under low pH condition.

Author information

1
State Key Laboratory of Material-oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 Puzhu Road, Nanjing, 211816, China.
2
Science and Technology Development Department, Sinopec Corporation, No. 22 Chaoyangmen North Street, Changyang District, Beijing, 100728, China.
3
Department of Biological Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
4
State Key Laboratory of Material-oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 Puzhu Road, Nanjing, 211816, China. biotech@njtech.edu.cn.

Abstract

Ensuring a suitable pH is a major problem in industrial organic acid fermentation. To circumvent this problem, we used a metabolic profiling approach to analyze metabolite changes in Rhizopus oryzae under different pH conditions. A correlation between fumaric acid production and intracellular metabolic characteristics of R. oryzae was revealed by principal component analysis. The results showed that to help cell survival in the presence of low pH, R. oryzae altered amino acid and fatty acid metabolism and promoted sugar or sugar alcohol synthesis, corresponding with a suppressing of energy metabolism, phenylalanine, and tyrosine synthesis and finally resulting in the low performance of fumaric acid production. Based on this observation, 1 % linoleic acid was added to the culture medium in pH 3.0 to decrease the carbon demand for cell survival, and the fumaric acid titer was enhanced by 39.7 % compared with the control (pH 3.0 without linoleic acid addition), reaching 18.3 g/L after 84 h of fermentation. These findings provide new insights into the mechanism by which R. oryzae responds to acidic stress and would be helpful for the development of efficient strategies for fumaric acid production at low pH.

KEYWORDS:

Acidic stress; Fumaric acid; Metabolic profile; Rhizopus oryzae

PMID:
26481229
DOI:
10.1007/s12010-015-1831-8
[Indexed for MEDLINE]

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