title: Revealing differences in metabolic flux distributions between a mutant strain and its parent strain Gluconacetobacter xylinus CGMCC 2955.
abstract: A better understanding of metabolic fluxes is important for manipulating microbial metabolism toward desired end products, or away from undesirable by-products. A mutant strain, Gluconacetobacter xylinus AX2-16, was obtained by combined chemical mutation of the parent strain (G. xylinus CGMCC 2955) using DEC (diethyl sulfate) and LiCl. The highest bacterial cellulose production for this mutant was obtained at about 11.75 g/L, which was an increase of 62% compared with that by the parent strain. In contrast, gluconic acid (the main byproduct) concentration was only 5.71 g/L for mutant strain, which was 55.7% lower than that of parent strain. Metabolic flux analysis indicated that 40.1% of the carbon source was transformed to bacterial cellulose in mutant strain, compared with 24.2% for parent strain. Only 32.7% and 4.0% of the carbon source were converted into gluconic acid and acetic acid in mutant strain, compared with 58.5% and 9.5% of that in parent strain. In addition, a higher flux of tricarboxylic acid (TCA) cycle was obtained in mutant strain (57.0%) compared with parent strain (17.0%). It was also indicated from the flux analysis that more ATP was produced in mutant strain from pentose phosphate pathway (PPP) and TCA cycle. The enzymatic activity of succinate dehydrogenase (SDH), which is one of the key enzymes in TCA cycle, was 1.65-fold higher in mutant strain than that in parent strain at the end of culture. It was further validated by the measurement of ATPase that 3.53-6.41 fold higher enzymatic activity was obtained from mutant strain compared with parent strain.
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, (Ministry of Education), Tianjin University of Science & Technology, Tianjin, People's Republic of China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhong
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, (Ministry of Education), Tianjin University of Science & Technology, Tianjin, People's Republic of China; DeFENS, Department of Food Environmental and Nutritional Sciences, University of Milan, Milan, Italy.
authors.forename: Fei
authors.initials: F
authors.lastname: Li
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, (Ministry of Education), Tianjin University of Science & Technology, Tianjin, People's Republic of China.
authors.forename: Miao
authors.initials: M
authors.lastname: Liu
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, (Ministry of Education), Tianjin University of Science & Technology, Tianjin, People's Republic of China.
authors.forename: Xiao-Ning
authors.initials: XN
authors.lastname: Yang
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, (Ministry of Education), Tianjin University of Science & Technology, Tianjin, People's Republic of China.
authors.forename: Hui-Xia
authors.initials: HX
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, (Ministry of Education), Tianjin University of Science & Technology, Tianjin, People's Republic of China; Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Tianjin, People's Republic of China.
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Jia
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, (Ministry of Education), Tianjin University of Science & Technology, Tianjin, People's Republic of China.
authors.forename: Shi-Ru
authors.initials: SR
authors.lastname: Jia
authors.affiliation: DeFENS, Department of Food Environmental and Nutritional Sciences, University of Milan, Milan, Italy.
authors.forename: Luciano
authors.initials: L
authors.lastname: Piergiovanni
mesh_terms: D002482:Cellulose / Q000096:biosynthesis; D002952:Citric Acid Cycle; D004734:Energy Metabolism; D041822:Gluconacetobacter xylinus / Q000235:genetics* / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D009154:Mutation
chemical_list: D002482:Cellulose