Biosynthesis of polyhydroxyalkanoate homopolymers by Pseudomonas putida

Wang, Honghui; Zhou, Xinrong; Liu, Qian; Chen, Guoqiang

doi:10.1007/s00253-010-2964-x

Cited by 134 publications

(93 citation statements)

References 32 publications

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“…In subsequently carried out simulations, octanoate enabled the highest yield (Figure 3b). Assuming the presence of an ACP-ligase [39], octanoate requires only activation by CoA/ACP to form HAA (Figure 4), thereby avoiding metabolically expensive de novo lipid synthesis. The rhamnose moiety requires β-oxidation and gluconeogenic reactions.…”

Section: Resultsmentioning

confidence: 99%

Growth independent rhamnolipid production from glucose using the non-pathogenic Pseudomonas putida KT2440

et al. 2011

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BackgroundRhamnolipids are potent biosurfactants with high potential for industrial applications. However, rhamnolipids are currently produced with the opportunistic pathogen Pseudomonas aeruginosa during growth on hydrophobic substrates such as plant oils. The heterologous production of rhamnolipids entails two essential advantages: Disconnecting the rhamnolipid biosynthesis from the complex quorum sensing regulation and the opportunity of avoiding pathogenic production strains, in particular P. aeruginosa. In addition, separation of rhamnolipids from fatty acids is difficult and hence costly.ResultsHere, the metabolic engineering of a rhamnolipid producing Pseudomonas putida KT2440, a strain certified as safety strain using glucose as carbon source to avoid cumbersome product purification, is reported. Notably, P. putida KT2440 features almost no changes in growth rate and lag-phase in the presence of high concentrations of rhamnolipids (> 90 g/L) in contrast to the industrially important bacteria Bacillus subtilis, Corynebacterium glutamicum, and Escherichia coli. P. putida KT2440 expressing the rhlAB-genes from P. aeruginosa PAO1 produces mono-rhamnolipids of P. aeruginosa PAO1 type (mainly C10:C10). The metabolic network was optimized in silico for rhamnolipid synthesis from glucose. In addition, a first genetic optimization, the removal of polyhydroxyalkanoate formation as competing pathway, was implemented. The final strain had production rates in the range of P. aeruginosa PAO1 at yields of about 0.15 g/gglucose corresponding to 32% of the theoretical optimum. What's more, rhamnolipid production was independent from biomass formation, a trait that can be exploited for high rhamnolipid production without high biomass formation.ConclusionsA functional alternative to the pathogenic rhamnolipid producer P. aeruginosa was constructed and characterized. P. putida KT24C1 pVLT31_rhlAB featured the highest yield and titer reported from heterologous rhamnolipid producers with glucose as carbon source. Notably, rhamnolipid production was uncoupled from biomass formation, which allows optimal distribution of resources towards rhamnolipid synthesis. The results are discussed in the context of rational strain engineering by using the concepts of synthetic biology like chassis cells and orthogonality, thereby avoiding the complex regulatory programs of rhamnolipid production existing in the natural producer P. aeruginosa.

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Section: Resultsmentioning

confidence: 99%

Growth independent rhamnolipid production from glucose using the non-pathogenic Pseudomonas putida KT2440

et al. 2011

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“…A melting point of 68°C had been previously predicted 5 for PHO homopolymer, while a melting point of 66°C was measured in a polymer of PHO containing 98% HO and 2% HHx. 10 These effects were not due to a change in the crystalline structure (shown by X-ray diffraction in Figure 6) but rather the relative degree of crystallization as determined from the heat of fusion (ΔH in Table 1), which increased steadily (from 12 to 27 J g −1 for PHN and from 9 to 15 J g −1 for PHO) with increasing dominant monomer content. Other mechanical properties such as tensile stress at break and Young's modulus were also significantly improved with increasing amounts of the dominant monomer.…”

Section: ■ Discussionmentioning

confidence: 96%

Biosynthesis and Properties of Medium-Chain-Length Polyhydroxyalkanoates with Enriched Content of the Dominant Monomer

et al. 2012

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When grown in a nonanoic acid-limited chemostat at a dilution rate of 0.25 h(-1), Pseudomonas putida KT2440 produced poly(3-hydroxynonanoate-co-3-hydroxyheptanoate) containing 68 mol % 3-hydroxynonanoate (C9) and 32 mol % 3-hydroxyheptanoate (C7). Under the same conditions, but in the presence of acrylic acid, a fatty acid β-oxidation inhibitor, the C9 monomer content increased to 88 mol %. Cofeeding glucose (3.9 g L(-1)) and nonanoic acid (2.9 ± 0.1 g L(-1)) in continuous culture with 0.2 g L(-1) of acrylic acid in the feed, further increased the C9 content to 95 mol %. A yield of PHA from nonanoic acid of 0.93 mol mol(-1) was attained. PHA with a 3-hydroxyoctanoate (C8) content of 98 mol % was produced with the same cofeeding methodology from octanoic acid. As the dominant monomer content increased, the melting point of the poly(3-hydroxynonanoate) copolymers increased from 46 to 63 °C and that of the poly(3-hydroxyoctanoate) copolymers from 54 to 62 °C. All copolymer compositions resulted in elongation to break values of about 1300%, but tensile strength at break and Young's modulus both increased with increasing amounts of the dominant monomer.

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“…Scl-PHAs are highly crystalline and mcl-PHAs are elastomeric in nature. 3,4 PHA homopolymers, such as poly-3-hydroxybutyrate (P(3HB)), 5 poly-3-hydroxyvalerate (P(3HV)), 6 poly-4-hydroxybutyrate (P(4HB)), 7 poly-3-hydroxyhexanoate (P(3H Hx)), 8 poly-3-hydroxyoctanoate (P(3HO)), 9 poly-3-hydroxydecanoate (P(3HD)), 9 and poly-3-hydroxydodecanoate (P(3HDD)), 9 have different physical properties, range from brittle and rigid to flexible and tough. PHA copolymers, such as P(3HB-co-3HV), 10 P(3HB-co-mcl-PHAs), 11 P(3HB-co3HHx), 12 and P(3HB-co-3HV-co-4HB), 13 exhibit improved and favorable mechanical properties, conferred from the ratio of individual monomer units (Table I).…”

Section: Introductionmentioning

confidence: 99%

Bioplastics from waste glycerol derived from biodiesel industry

Zhu

Chiu

Nakas

et al. 2013

J of Applied Polymer Sci

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Polyhydroxyalkanoates (PHAs) are polyesters that can be biologically synthesized by many microorganisms and engineered plants that have been investigated by microbiologists, biochemists, polymer scientists, material engineers, and medical researchers for several decades. Research on microbial production of PHAs has been extensively focused on using pure carbon sources, such as sugars and fatty acids. Practical considerations of production costs of PHAs have resulted in research efforts to use alternative renewable and inexpensive feedstocks. One potential feedstock for the production of PHA polymers is the glycerol waste byproduct of biodiesel production. The major focus of this review is the production of PHA polymers from glycerol. A review of biosynthetic pathways for PHAs production from glycerol, current production of waste glycerol in biodiesel industry, physical and mechanical properties of PHAs, and applications of PHAs in the areas of packaging industry, implant materials, drug carrier, biofuels, are covered.

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Biosynthesis of polyhydroxyalkanoate homopolymers by Pseudomonas putida

Cited by 134 publications

References 32 publications

Growth independent rhamnolipid production from glucose using the non-pathogenic Pseudomonas putida KT2440

Growth independent rhamnolipid production from glucose using the non-pathogenic Pseudomonas putida KT2440

Biosynthesis and Properties of Medium-Chain-Length Polyhydroxyalkanoates with Enriched Content of the Dominant Monomer

Bioplastics from waste glycerol derived from biodiesel industry

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