Efficient production of medium-chain-length poly(3-hydroxyalkanoates) from octane by Pseudomonas oleovorans : economic considerations

Hazenberg, Wil; Witholt, Bernard

doi:10.1007/s002530051100

Cited by 53 publications

(25 citation statements)

References 22 publications

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“…For example, the decrease of formed CDW above the dualnutrient-limited growth zone at dilution rates of 0.4 and 0.3 h Ϫ1 may have been caused by the inhibitory effect of residual octanoate (compare reference 35). Additionally, it has been pointed out recently that for the industrial production of mcl-PHA, the amount of carbon substrate used must be minimized because the price of the carbon source has a major influence on the production costs of the end product (8,17). Cultivation of the cells at the upper boundary of the dual-nutrient-limited growth zone satisfies both requirements: low actual concentrations of possibly unfavorable nutrients and optimum utilization of the growth substrates supplied.…”

Section: Discussionmentioning

confidence: 99%

“…mcl-PHAs are hydrophobic polyesters and are attracting increasing interest for their possible application as biologically produced and inherently biodegradable substitutes for conventional plastic materials (6,8,10,20,32). Particularly, when subjected to nitrogen limitation in batch (22, 24) and chemostat culture (17,33,34), P. oleovorans has been reported to accumulate high cellular mcl-PHA contents.The nature and availability of essential nutrients are important parameters in determining the extent of storage compound accumulation in P. oleovorans (23,24). Generally, the production of microbial cell mass is limited by the restricted availability of a particular nutrient.…”

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confidence: 99%

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Accumulation of Poly[( R )-3-Hydroxyalkanoates] in Pseudomonas oleovorans during Growth with Octanoate in Continuous Culture at Different Dilution Rates

Durner

Witholt

Egli

2000

Appl Environ Microbiol

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Pseudomonas oleovorans ATCC 29347 was grown in chemostat culture at different dilution rates with mineral media varying in their ratios of octanoate to ammonia (C 0 /N 0 ratio). At all dilution rates tested, three distinct growth regimes were observed: (i) carbon limitation with NH 4 ؉ in excess at low C 0 /N 0 ratios, (ii) purely nitrogen-limited growth conditions at high C 0 /N 0 ratios with residual octanoate in the culture supernatant, and (iii) an intermediate zone of dual-nutrient-limited growth conditions where both the concentration of octanoate and that of ammonia were very low. The dual-nutrient-limited growth zone shifted to higher C 0 /N 0 ratios with decreasing dilution rates, and the extension of the dual-nutrient-limited growth zone was inversely proportional to the growth rate. The cells accumulated the storage compound medium-chain-length poly[(R)-3-hydroxyalkanoate] (mcl-PHA) during dual (C and N)-nutrient-limited and N-limited growth conditions. Within the dual-nutrient-limited growth zone, the cellular mcl-PHA contents increased when the C 0 /N 0 ratio in the feed was increased, whereas the cellular mcl-PHA level was independent from the feed C 0 /N 0 ratio during N-limited growth. The monomeric composition of the accumulated mcl-PHA was independent of both the dilution rate and the feed C 0 /N 0 ratio and consisted of 12 mol% 3-hydroxyhexanoic acid and 88 mol% 3-hydroxyoctanoic acid. Accumulation of mcl-PHA led to an increase in the cellular C/N ratio and to changes in elemental growth yields for nitrogen and carbon.Pseudomonas oleovorans is able to accumulate mediumchain-length poly[(R)-3-hydroxyalkanoates] (mcl-PHAs) as intracellular carbon and energy storage compounds when grown with alkanes (9, 24), mcl-alkanoates (3, 21), n-alkanols (16), or many derivatives thereof (27,38). mcl-PHAs are hydrophobic polyesters and are attracting increasing interest for their possible application as biologically produced and inherently biodegradable substitutes for conventional plastic materials (6,8,10,20,32). Particularly, when subjected to nitrogen limitation in batch (22, 24) and chemostat culture (17,33,34), P. oleovorans has been reported to accumulate high cellular mcl-PHA contents.The nature and availability of essential nutrients are important parameters in determining the extent of storage compound accumulation in P. oleovorans (23,24). Generally, the production of microbial cell mass is limited by the restricted availability of a particular nutrient. In batch culture, the exhaustion of a specific nutrient terminates the exponentialgrowth phase, whereas in chemostat culture the biomass concentration is usually controlled by the permanent limitation of a single defined nutrient, typically the carbon and energy source. However, several authors have shown that two or more nutrients can simultaneously limit the production of biomass (for a summary, see reference 14). This phenomenon has also been observed for P. oleovorans, where we have found that under defined chemostat steady-state cultivation c...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Accumulation of Poly[( R )-3-Hydroxyalkanoates] in Pseudomonas oleovorans during Growth with Octanoate in Continuous Culture at Different Dilution Rates

Durner

Witholt

Egli

2000

Appl Environ Microbiol

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“…To overcome degradation of the products of the xylene monooxygenase from P. putida, the xyl genes from the TOL plasmid encoding this enzyme may be inserted in E. coli (672). P. oleovorans can convert octane to medium-chain poly(3-hydroxyalkanoates), with potential for use in biodegradable plastics (247), at projected large-scale manufacturing costs of less than US$10 per kg (348).…”

Section: Enzymatic Upgrading Of Petroleum Fractions and Pure Hydrocarmentioning

confidence: 99%

Recent Advances in Petroleum Microbiology

Hamme¹,

Singh

Ward

2003

Microbiol Mol Biol Rev

1,201

640

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Recent advances in molecular biology have extended our understanding of the metabolic processes related to microbial transformation of petroleum hydrocarbons. The physiological responses of microorganisms to the presence of hydrocarbons, including cell surface alterations and adaptive mechanisms for uptake and efflux of these substrates, have been characterized. New molecular techniques have enhanced our ability to investigate the dynamics of microbial communities in petroleum-impacted ecosystems. By establishing conditions which maximize rates and extents of microbial growth, hydrocarbon access, and transformation, highly accelerated and bioreactor-based petroleum waste degradation processes have been implemented. Biofilters capable of removing and biodegrading volatile petroleum contaminants in air streams with short substrate-microbe contact times (<60 s) are being used effectively. Microbes are being injected into partially spent petroleum reservoirs to enhance oil recovery. However, these microbial processes have not exhibited consistent and effective performance, primarily because of our inability to control conditions in the subsurface environment. Microbes may be exploited to break stable oilfield emulsions to produce pipeline quality oil. There is interest in replacing physical oil desulfurization processes with biodesulfurization methods through promotion of selective sulfur removal without degradation of associated carbon moieties. However, since microbes require an environment containing some water, a two-phase oil-water system must be established to optimize contact between the microbes and the hydrocarbon, and such an emulsion is not easily created with viscous crude oil. This challenge may be circumvented by application of the technology to more refined gasoline and diesel substrates, where aqueous-hydrocarbon emulsions are more easily generated. Molecular approaches are being used to broaden the substrate specificity and increase the rates and extents of desulfurization. Bacterial processes are being commercialized for removal of H2S and sulfoxides from petrochemical waste streams. Microbes also have potential for use in removal of nitrogen from crude oil leading to reduced nitric oxide emissions provided that technical problems similar to those experienced in biodesulfurization can be solved. Enzymes are being exploited to produce added-value products from petroleum substrates, and bacterial biosensors are being used to analyze petroleum-contaminated environments

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“…To obtain a polymer with high 3-hydroxyoctanoate content, the use of octanoic acid as the carbon source is preferred (22,26,31,35,49). Using fatty acids with a greater carbon chain length resulted in PHAs consisting of a larger variety of constituents.…”

Section: Discussionmentioning

confidence: 99%

Large-Scale Production of Poly(3-Hydroxyoctanoic Acid) by Pseudomonas putida GPo1 and a Simplified Downstream Process

Elbahloul

Steinbüchel

2009

Appl Environ Microbiol

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The suitability of Pseudomonas putida GPo1 for large-scale cultivation and production of poly(3-hydroxyoctanoate) (PHO) was investigated in this study. Three fed-batch cultivations of P. putida GPo1 at the 350-or 400-liter scale in a bioreactor with a capacity of 650 liters were done in mineral salts medium containing initially 20 mM sodium octanoate as the carbon source. The feeding solution included ammonium octanoate, which was fed at a relatively low concentration to promote PHO accumulation under nitrogen-limited conditions. During cultivation, the pH was regulated by addition of NaOH, NH 4 OH, or octanoic acid, which was used as an additional carbon source. Partial O 2 pressure (pO 2 ) was adjusted to 20 to 40% by controlling the airflow and stirrer speed. Under the optimized conditions, P. putida GPo1 was able to grow to cell densities as high as 18, 37, and 53 g cells (dry mass) (CDM) per liter containing 49, 55, and 60% (wt/wt) of PHO, respectively. The resulting 40 kg CDM from these three cultivations was used directly for extraction of PHO. Three different methods of extraction of PHO were applied. From these, only acetone extraction showed better performance and resulted in 94% recovery of the PHO contents of cells. A novel mixture of precipitation solvents composed of 70% (vol/vol) methanol and 70% (vol/vol) ethanol was identified in this study. The ratio of PHO concentrate to the mixture was 0.2:1 (vol/vol) and allowed complete precipitation of PHO as white flakes. However, at a ratio of 1:1 (vol/vol) of the solvent mixture to PHO concentrate, a highly purified PHO was obtained. Precipitation yielded a dough-like polymeric material which was cast into thin layers and then shredded into small strips to allow evaporation of the remaining solvents. Gas chromatographic analysis revealed a purity of about 99% ؎ 0.2% (wt/wt) of the polymer, which consisted mainly of 3-hydroxyoctanoic acid (96 mol%).

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Efficient production of medium-chain-length poly(3-hydroxyalkanoates) from octane by Pseudomonas oleovorans : economic considerations

Cited by 53 publications

References 22 publications

Accumulation of Poly[( R )-3-Hydroxyalkanoates] in Pseudomonas oleovorans during Growth with Octanoate in Continuous Culture at Different Dilution Rates

Accumulation of Poly[( R )-3-Hydroxyalkanoates] in Pseudomonas oleovorans during Growth with Octanoate in Continuous Culture at Different Dilution Rates

Recent Advances in Petroleum Microbiology

Large-Scale Production of Poly(3-Hydroxyoctanoic Acid) by Pseudomonas putida GPo1 and a Simplified Downstream Process

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