Bioconversions of aliphatic compounds byPseudomonas oleovorans in multiphase bioreactors: background and economic potential

Witholt, Bernard; Desmet, Mj; Kingma, Jaap; Beilen, Jan B. van; Kok, Menno; Lageveen, Rg; Eggink, Gerrit

doi:10.1016/0167-7799(90)90133-i

Cited by 163 publications

(75 citation statements)

References 41 publications

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“…According to the toxicity data for styrene and its products (54), these compounds were present at subtoxic concentrations during the continuous biotransformation experiments performed VOL. 74,2008 NADH AVAILABILITY LIMITS WHOLE-CELL EPOXIDATION 1443 in this study. In the absence of styrene epoxidation, styrene oxide, for example, had no influence on cell growth and acetate formation at concentrations of below 150 mM in the organic phase (54).…”

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confidence: 97%

“…Enzyme synthesis and cofactor regeneration are related to host metabolism, which in turn may be affected by the toxicity of organic substrates and products. Such toxicity can efficiently be attenuated by regulated substrate feeding (1,11) and in situ product removal (7,38,61,66,74). Yet, microbial cells, especially in a nongrowing state, often lose biooxidation activity over time, which may be due to oxygenase inactivation and/or the metabolic burden imposed by redox-coenzyme withdrawal and reactive oxygen species formed via uncoupled oxygen reduction.…”

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confidence: 99%

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NADH Availability Limits Asymmetric Biocatalytic Epoxidation in a Growing Recombinant Escherichia coli Strain

Bühler

Park

Blank

et al. 2008

Appl Environ Microbiol

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Styrene can efficiently be oxidized to (S)-styrene oxide by recombinant Escherichia coli expressing the styrene monooxygenase genes styAB from Pseudomonas sp. strain VLB120. Targeting microbial physiology during whole-cell redox biocatalysis, we investigated the interdependency of styrene epoxidation, growth, and carbon metabolism on the basis of mass balances obtained from continuous two-liquid-phase cultures. Full induction of styAB expression led to growth inhibition, which could be attenuated by reducing expression levels. Operation at subtoxic substrate and product concentrations and variation of the epoxidation rate via the styrene feed concentration allowed a detailed analysis of carbon metabolism and bioconversion kinetics. Fine-tuned styAB expression and increasing specific epoxidation rates resulted in decreasing biomass yields, increasing specific rates for glucose uptake and the tricarboxylic acid (TCA) cycle, and finally saturation of the TCA cycle and acetate formation. Interestingly, the biocatalysis-related NAD(P)H consumption was 3.2 to 3.7 times higher than expected from the epoxidation stoichiometry. Possible reasons include uncoupling of styrene epoxidation and NADH oxidation and increased maintenance requirements during redox biocatalysis. At epoxidation rates of above 21 mol per min per g cells (dry weight), the absence of limitations by O 2 and styrene and stagnating NAD(P)H regeneration rates indicated that NADH availability limited styrene epoxidation. During glucose-limited growth, oxygenase catalysis might induce regulatory stress responses, which attenuate excessive glucose catabolism and thus limit NADH regeneration. Optimizing metabolic and/or regulatory networks for efficient redox biocatalysis instead of growth (yield) is likely to be the key for maintaining high oxygenase activities in recombinant E. coli.Oxygenases catalyze regio-and enantioselective oxyfunctionalization reactions and have a considerable potential in the area of asymmetric organic synthesis (2, 35). These enzymes typically depend on coenzymes such as NAD(P)H and are unstable outside cells, and they often consist of multiple components. Thus, for synthetic applications, their use in whole cells is favored over the use of isolated enzymes (7,18).The productivity of oxygenase-based whole-cell biocatalysts is influenced by various factors, such as maximal enzyme activity, enzyme level, substrate mass transfer, substrate and/or product inhibition/toxicity, and cofactor regeneration (7,13,54,68). Enzyme synthesis and cofactor regeneration are related to host metabolism, which in turn may be affected by the toxicity of organic substrates and products. Such toxicity can efficiently be attenuated by regulated substrate feeding (1, 11) and in situ product removal (7,38,61,66,74). Yet, microbial cells, especially in a nongrowing state, often lose biooxidation activity over time, which may be due to oxygenase inactivation and/or the metabolic burden imposed by redox-coenzyme withdrawal and reactive oxygen species formed via...

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mentioning

confidence: 97%

mentioning

confidence: 99%

NADH Availability Limits Asymmetric Biocatalytic Epoxidation in a Growing Recombinant Escherichia coli Strain

Bühler

Park

Blank

et al. 2008

Appl Environ Microbiol

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“…DG17 increased to 47AE25% in the stationary phase. Microbial cells are adapted to (Scott and Finnerty 1976;Witholt et al 1990;Heipieper et al 2003). Similarly, Chen et al (2007) found that in the addition of rhamnolipid, the BATH of Bacillus sp.…”

Section: Discussionmentioning

confidence: 99%

Uptake modes of octadecane by Pseudomonas sp. DG17 and synthesis of biosurfactant

Fei¹,

Wang²

2011

Journal of Applied Microbiology

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Aims: In order to gain more insight into the uptake modes of octadecane by bacteria. Methods and Results: A strain that could utilize octadecane well was isolated from crude oil contaminated soil, and named as Pseudomonas sp. DG17 by 16S rDNA analysis. Culture growth result showed that Pseudomonas sp. DG17 grew well in the addition of 200 and 400 mg l−1 of octadecane, which showed that physical contact between substrate and bacteria was important in the substrate biodegradation. Meanwhile, Pseudomonas sp. DG17 produced rhamnolipids biosurfactant that contains 10 congeners, thus causing the surface tension of the culture medium decline and facilitating the contact between hydrocarbon and bacteria. Scanning‐electron‐microscopy results showed that a disruption of the surface membranes in certain zones was observed in some of the cells grown in 400 mg l−1 octadecane at 176 h compared with the cells in exponential phase at 72 h due to the production of biosurfactant‐rhamnolipid. Conclusions: These results indicated the possibility that the direct contact with insoluble octadecane droplets occurred before the contact with pseudosolubilization smaller oil droplets. Significance: This report throws more light on the uptake mechanisms of octadecane by bacteria, and proposes the possibility that role of biosurfactant is to increase the contact between hydrocarbon and bacteria by changing the cell membrane structure which needs studied in depth. Impact of Study: Results of this study are useful in the bioremediation of petroleum polluted soil.

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“…Even though several studies have shown that the alkB genes are widespread in nature [166], only the Pseudomonas putida GPo1 alkane hydroxylase system [167] has been studied in detail with respect to enzymology, genetics, as well as potential applications [28,167,168]. The alkane hydroxylase system of GPo1 consists of three components: a particulate hydroxylase (AlkB), which is the catalytic component localized in the cytoplasmic membrane, and two soluble proteins, rubredoxin (AlkG) and rubredoxin reductase (AlkT) ( Fig.…”

Section: Alkb In Pseudomonas Putida Gpo1mentioning

confidence: 99%

Monooxygenases involved in the n-alkanes metabolism by Rhodococcus sp. BCP1: molecular characterization and expression of alkB gene

Cappelletti

Fedi

Honda

et al. 2010

Journal of Biotechnology

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Discussion 107 Summary 113Chapter 5 -Analysis of the alkB gene expression Summary 157Chapter 6 -Proteomic analysis of n-alkanes growth of Rhodococcus sp. BCP1 Chapter 1 -General Introduction PrefaceThe quality of life on Earth is tightly related with the overall quality of the environment [1]. During the last century it was commonly believed that the abundance of land and resources were unlimited and it was rarely acknowledged that the production, use, and disposal of hazardous substances had environmental and health effects [1][2][3]. Owing to this, human activity has deliberately or inadvertently released into waters and soil a variety of toxic compounds as refrigerants, paints, solvents, herbicides and pesticides that can cause considerable environmental pollution and human health problems as a result of their persistence, toxicity, and transformation into hazardous metabolites [4,5]. Very soon, however, it became clear how the carelessness and negligence in handling the industrial wastes and gas emissions had caused dramatic effect on the nature and on human health [1].Nowadays, the concern about the global warming and the climate changing induced the government regulatory agencies to establish procedures for assessing the environmental impact and health hazards of chemicals and for controlling/limiting their utilization.International efforts have been applied to remedy many contaminated sites all over the world, either as a response to the risk of adverse health or environmental effects caused by contamination or to enable the site to be redeveloped for use [5]. In response to public and government concern and because of the intriguing research problems presented, environmental scientists, biologists and chemists have been giving increased attention to identifying and determining the behavior and fate of organic compounds in natural ecosystems [5].Bioremediation procedures offer an economical and effective possibility to degrade or render innocuous toxic pollutants using natural biological activity [1]. By definition, bioremediation implies the use of living organisms, primarily microorganisms, to degrade the Since contaminant compounds are transformed by living organisms through reactions that take place as a part of their metabolic processes, environmental biotechnology focuses on the development of techniques to optimize environmental parameters to allow these metabolic pathways to proceed faster and, therefore, to improve the bio-degradation [1]. As a result, the removal of the contaminated soil can be necessary to let the biodegradation proceed in controlled sites (such as bioreactors). These ex situ approaches provide optimal conditions out one single step of the entire bio-degradation process. Hydrocarbons in the environmentHydrocarbons are energy-rich organic compounds consisting of carbon and hydrogen atoms and they can be saturated (only single C-H bounds) or unsaturated (one ore more double or triple C-H bounds). Alkanes are saturated hydrocarbons with the general formula C n H 2n+2 ; they can b...

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Bioconversions of aliphatic compounds byPseudomonas oleovorans in multiphase bioreactors: background and economic potential

Cited by 163 publications

References 41 publications

NADH Availability Limits Asymmetric Biocatalytic Epoxidation in a Growing Recombinant Escherichia coli Strain

NADH Availability Limits Asymmetric Biocatalytic Epoxidation in a Growing Recombinant Escherichia coli Strain

Uptake modes of octadecane by Pseudomonas sp. DG17 and synthesis of biosurfactant

Monooxygenases involved in the n-alkanes metabolism by Rhodococcus sp. BCP1: molecular characterization and expression of alkB gene

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