Effects of pH of Fermentation Medium on Biosynthesis of Poly[(3‐hydroxybutyrate)‐<i>co</i>‐(3‐mercaptopropionate)] by <i>Wautersia eutropha</i>

Isemori, Yuichi; Tajima, Koichiro; Tanaka, Syogo; Fang, Yu; Ishida, Kohtaro; Inoue, Yoshio

doi:10.1002/mabi.200600133

Cited by 7 publications

(19 citation statements)

References 31 publications

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“…The model predicted that the Y PHB increased as pH increases, which well agrees with our experimental data shown in Figure 2B. This observation was also supported by previous report, in which the yield of poly[(3-hydroxybutyrate)-co-(3-mercaptopropionate)] from R. eutropha was greatest at pH 8 in the range between pH 6 and 8 [37]. Taken together, use of RehMBEL1391 further provides in silico confirmation that pH value of fermentation medium significantly influences the polymer yield and its yield is optimal under mild basic condition.…”

Section: Resultssupporting

confidence: 92%

“…For PHB production in R. eutropha , pH is known to play an important role [37]. In order to gain better insight into the effects of pH on the capability of R. eutropha to produce PHB, RehMBEL1391 whose metabolic reactions are elementally and charge balanced for pH 6, 7, and 8 was systematically simulated (see Additional file 7 for the relevant mol files to estimate the charges of metabolites at different pH values using MarvinBeans software).…”

Section: Resultsmentioning

confidence: 99%

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Genome-scale reconstruction and in silico analysis of the Ralstonia eutropha H16 for polyhydroxyalkanoate synthesis, lithoautotrophic growth, and 2-methyl citric acid production

2011

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BackgroundRalstonia eutropha H16, found in both soil and water, is a Gram-negative lithoautotrophic bacterium that can utillize CO2 and H2 as its sources of carbon and energy in the absence of organic substrates. R. eutropha H16 can reach high cell densities either under lithoautotrophic or heterotrophic conditions, which makes it suitable for a number of biotechnological applications. It is the best known and most promising producer of polyhydroxyalkanoates (PHAs) from various carbon substrates and is an environmentally important bacterium that can degrade aromatic compounds. In order to make R. eutropha H16 a more efficient and robust biofactory, system-wide metabolic engineering to improve its metabolic performance is essential. Thus, it is necessary to analyze its metabolic characteristics systematically and optimize the entire metabolic network at systems level.ResultsWe present the lithoautotrophic genome-scale metabolic model of R. eutropha H16 based on the annotated genome with biochemical and physiological information. The stoichiometic model, RehMBEL1391, is composed of 1391 reactions including 229 transport reactions and 1171 metabolites. Constraints-based flux analyses were performed to refine and validate the genome-scale metabolic model under environmental and genetic perturbations. First, the lithoautotrophic growth characteristics of R. eutropha H16 were investigated under varying feeding ratios of gas mixture. Second, the genome-scale metabolic model was used to design the strategies for the production of poly[R-(-)-3hydroxybutyrate] (PHB) under different pH values and carbon/nitrogen source uptake ratios. It was also used to analyze the metabolic characteristics of R. eutropha when the phosphofructokinase gene was expressed. Finally, in silico gene knockout simulations were performed to identify targets for metabolic engineering essential for the production of 2-methylcitric acid in R. eutropha H16.ConclusionThe genome-scale metabolic model, RehMBEL1391, successfully represented metabolic characteristics of R. eutropha H16 at systems level. The reconstructed genome-scale metabolic model can be employed as an useful tool for understanding its metabolic capabilities, predicting its physiological consequences in response to various environmental and genetic changes, and developing strategies for systems metabolic engineering to improve its metabolic performance.

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Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Genome-scale reconstruction and in silico analysis of the Ralstonia eutropha H16 for polyhydroxyalkanoate synthesis, lithoautotrophic growth, and 2-methyl citric acid production

2011

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“…20.2 wt.-% for fructose. [13] The results in Table 1 show the advantage of using plant oils for the biosynthesis of the copolymers.…”

Section: Resultsmentioning

confidence: 97%

“…Inoue et al synthesized poly(3HB-co-3MP) that contained the 3MP unit over a range of 16.7-48.0 mol-% by C. necator from sodium gluconate and 3,3-dithiodipropionic acid at different pH. [13] These earlier reported procedures were capable of inducing a wide range of 3MP unit fractions in the polymer chains. However, the yield of the copolythioesters was less than the corresponding polyoxoesters, because the sulfur-containing substrates were highly toxic to the microbial cells.…”

Section: Full Papermentioning

confidence: 99%

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Biosynthesis and Biodegradability of Copolythioesters from 3,3′‐Thiodipropionic Acid and Plant Oils by Cupriviadus necator

Kamei

Nagai

Nishida

et al. 2007

Macromolecular Bioscience

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To prepare sulfur-containing natural polymers effectively, several plant oils and 3,3'-thiodipropionic acid (TDP) have been used as carbon sources for the biosynthesis of copolymer poly[(3-hydroxybutyrate)-co-(3-mercaptopropionate)] [poly(3HB-co-3MP)] by a wild-type bacterium Cupriviadus necator H16. By using the plant oils, copolymer accumulation and incorporation of 3MP units are greater than those of cases using sugars. The 3MP fraction is controllable over a range of 1-39 mol-% by adjusting the cultivation conditions. Microbial degradability of the copolymers has been examined in an activated sludge supernatant. The biodegradation proceeded by two mechanisms: surface erosion and auto-catalytic hydrolysis, depending on the 3MP unit fraction, and show preferential degradation of 3HB unit sequences.

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Mechanical Properties of Comonomer‐Compositionally Fractionated Poly[(3‐hydroxybutyrate)‐co‐(3‐mercaptopropionate)] with Low 3‐Mercaptopropionate Unit Content

Fang

Dong

Zhu

et al. 2007

Macromolecular Bioscience

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The mechanical properties, such as Young's modulus, yield strength, and the elongation at breakage, were investigated for several sulfur-containing biopolymers P(3HB-co-3MP). A series of P(3HB-co-3MP) samples with 3MP unit content ranging from 6.6 to 39.1 mol-% was biosynthesized by fermentation using the PHA-synthesizing bacteria Cupriavidus necator. For comparison, the bacterially synthesized P(3HB) and P(3HB-co-3HP) with the 3HP unit content ranging from 13.1 to 21.1 mol-% were also investigated. It was found that the sulfur-containing P(3HB-co-3MP) is much more durable to stretching. Notably, P(3HB-co-3MP) with the 3MP unit content of only 6.6 mol-% was found to show excellent mechanical properties.

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Effects of pH of Fermentation Medium on Biosynthesis of Poly[(3‐hydroxybutyrate)‐co‐(3‐mercaptopropionate)] by Wautersia eutropha

Cited by 7 publications

References 31 publications

Genome-scale reconstruction and in silico analysis of the Ralstonia eutropha H16 for polyhydroxyalkanoate synthesis, lithoautotrophic growth, and 2-methyl citric acid production

Genome-scale reconstruction and in silico analysis of the Ralstonia eutropha H16 for polyhydroxyalkanoate synthesis, lithoautotrophic growth, and 2-methyl citric acid production

Biosynthesis and Biodegradability of Copolythioesters from 3,3′‐Thiodipropionic Acid and Plant Oils by Cupriviadus necator

Mechanical Properties of Comonomer‐Compositionally Fractionated Poly[(3‐hydroxybutyrate)‐co‐(3‐mercaptopropionate)] with Low 3‐Mercaptopropionate Unit Content

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