Mechanisms of membrane toxicity of hydrocarbons.

Sikkema, J.; Bont, J A de; Poolman, Berend

doi:10.1128/mmbr.59.2.201-222.1995

Cited by 1,545 publications

(792 citation statements)

References 289 publications

(446 reference statements)

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“…For moderately hydrophobic solutes such as PCP, the greater the concentration in the bulk solution, the more it will accumulate in the cellular lipid bilayer with a concomitant increase in toxicity (Sikkema, 1995). It was suggested that intracellular coenzymes, such as NADH and FAD, be used as intrinsic biomarkers for metabolic activity (Heikal, 2010), and since we have shown that resazurin can penetrate the cell membrane and be reduced by intracellular coenzymes, these rapid When studying cytotoxicity, the most commonly used assays are enzyme related methods (such as MTT, XTT, and LDH) (Riss et al, 2013), cell proliferation assays, and a fluorescence assay for adenylate kinase, and each assay has its own set of advantages and disadvantages.…”

Section: Effect Of the Duration Of Exposure To Pcp On Resazurin Redmentioning

confidence: 99%

Metabolic reduction of resazurin; location within the cell for cytotoxicity assays

Chen

Steele

Stuckey

2017

Biotech & Bioengineering

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Resazurin is widely used as a metabolic indicator for living cells, however, there has been considerable debate in the literature with regards to the specific location in the cell where the non-fluorescent resazurin is reduced to the strongly fluorescent resorufin. This lack of clarity about the reduction site makes the use of resazurin reduction data in cytotoxicity studies difficult to interpret. In this study, E. faecalis, a Gram-positive and facultative anaerobic bacterial strain, and the most toxic chlorophenol, pentachlorophenol (PCP), were chosen as models for an anaerobe and toxicant, respectively. By studying the kinetics of resazurin reduction by E. faecalis after different treatments (cell disruption, bacterial filtration, and pre-exposure to toxicant), we confirmed that resazurin reduction to resorufin by live Gram-positive and facultative anaerobic bacterial cells can only happen intracellularly under anaerobic conditions, while resorufin reduction to dihydroresorufin can happen both intracellularly and extracellularly. Based on the understanding of these fundamental mechanisms, we suggest that resazurin reduction can be used as a quick bioassay for measuring cytotoxicity.

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Section: Effect Of the Duration Of Exposure To Pcp On Resazurin Redmentioning

confidence: 99%

Metabolic reduction of resazurin; location within the cell for cytotoxicity assays

Chen

Steele

Stuckey

2017

Biotech & Bioengineering

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“…One reason is that industry-relevant biooxidation substrates and products often are toxic to living cells. Apolar substrates, such as aliphatic, aromatic, and heterocyclic compounds, accumulate in cellular membrane bilayers and promote membrane disintegration and permeabilization (Laane et al, 1987;Sikkema et al, 1995), which ultimately results in cell death (Park et al, 2006;Sikkema et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

Maximization of cell viability rather than biocatalyst activity improves whole‐cell ω‐oxyfunctionalization performance

Kadisch

Julsing

Schrewe

et al. 2016

Biotech & Bioengineering

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It is a common misconception in whole-cell biocatalysis to refer to an enzyme as the biocatalyst, thereby neglecting the structural and metabolic framework provided by the cell. Here, the low whole-cell biocatalyst stability, that is, the stability of specific biocatalyst activity, in a process for the terminal oxyfunctionalization of renewable fatty acid methyl esters was investigated. This reaction, which is difficult to achieve by chemical means, is catalyzed by Escherichia coli featuring the monooxygenase system AlkBGT and the uptake facilitator AlkL from Pseudomonas putida GPo1. Corresponding products, that is, terminal alcohols, aldehydes, and acids, constitute versatile bifunctional building blocks, which are of special interest for polymer synthesis. It could clearly be shown that extensive dodecanoic acid methyl ester uptake mediated by high AlkL levels leads to whole-cell biocatalyst toxification. Thus, cell viability constitutes the primary factor limiting biocatalyst stability and, as a result, process durability. Hence, a compromise had to be found between low biocatalyst activity due to restricted substrate uptake and poor biocatalyst stability due to AlkL-mediated toxification. This was achieved by the fine-tuning of heterologous alkL expression, which, furthermore, enabled the identification of the alkBGT expression level as another critical factor determining biocatalyst stability. Controlled synthesis of AlkL and reduced alkBGT expression finally enabled an increase of product titers by a factor of 4.3 up to 229 g L in a two-liquid phase bioprocess setup. Clearly, ω-oxyfunctionalization process performance was determined by cell viability and thus biocatalyst stability rather than the maximally achievable specific biocatalyst activity. Biotechnol. Bioeng. 2017;114: 874-884. © 2016 Wiley Periodicals, Inc.

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“…When hydrocarbons accumulate in the membrane lipid bilayer, the cell membrane loses its integrity and an increase in permeability to protons and ions is commonly observed. 189 Kamarainen et al evaluated several hydrocarbons and alcohols for their toxicity to Synechocystis 6803 and S. elongatus 7942. 177 Alcohols were the most inhibitory, followed by aldehydes and acids, and hydrocarbons were the least inhibitory.…”

Section: Improvements To Tolerance To Specific Compoundsmentioning

confidence: 99%

Molecular genetic improvements of cyanobacteria to enhance the industrial potential of the microbe: A review

Johnson

Gibbons

et al. 2016

Biotechnology Progress

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The rapid increase in worldwide population coupled with the increasing demand for fossil fuels has led to an increased urgency to develop sustainable sources of energy and chemicals from renewable resources. Using microorganisms to produce high-value chemicals and next-generation biofuels is one sustainable option and is the focus of much current research. Cyanobacteria are ideal platform organisms for chemical and biofuel production because they can be genetically engineered to produce a broad range of products directly from CO , H O, and sunlight, and require minimal nutrient inputs. The purpose of this review is to provide an overview on advances that have been or could be made to improve strains of cyanobacteria for industrial purposes. First, the benefits of using cyanobacteria as a platform for chemical and biofuel production are discussed. Next, an overview of cyanobacterial strain improvements by genetic engineering is provided. Finally, mutagenesis techniques to improve the industrial potential of cyanobacteria are described. Along with providing an overview on various areas of research that are currently being investigated to improve the industrial potential of cyanobacteria, this review aims to elucidate potential targets for future research involving cyanobacteria as an industrial microorganism. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1357-1371, 2016.

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Mechanisms of membrane toxicity of hydrocarbons.

Cited by 1,545 publications

References 289 publications

Metabolic reduction of resazurin; location within the cell for cytotoxicity assays

Metabolic reduction of resazurin; location within the cell for cytotoxicity assays

Maximization of cell viability rather than biocatalyst activity improves whole‐cell ω‐oxyfunctionalization performance

Molecular genetic improvements of cyanobacteria to enhance the industrial potential of the microbe: A review

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