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International Journal of Molecular... Feb 2018-4-(4-hydroxyphenyl)-2-butanol (rhododendrol (RD))-a skin-whitening ingredient-was reported to induce leukoderma in some consumers. We have examined the biochemical... (Review)
Review
-4-(4-hydroxyphenyl)-2-butanol (rhododendrol (RD))-a skin-whitening ingredient-was reported to induce leukoderma in some consumers. We have examined the biochemical basis of the RD-induced leukoderma by elucidating the metabolic fate of RD in the course of tyrosinase-catalyzed oxidation. We found that the oxidation of racemic RD by mushroom tyrosinase rapidly produces RD-quinone, which gives rise to secondary quinone products. Subsequently, we confirmed that human tyrosinase is able to oxidize both enantiomers of RD. We then showed that B16 cells exposed to RD produce high levels of RD-pheomelanin and protein-SH adducts of RD-quinone. Our recent studies showed that RD-eumelanin-an oxidation product of RD-exhibits a potent pro-oxidant activity that is enhanced by ultraviolet-A radiation. In this review, we summarize our biochemical findings on the tyrosinase-dependent metabolism of RD and related studies by other research groups. The results suggest two major mechanisms of cytotoxicity to melanocytes. One is the cytotoxicity of RD-quinone through binding with sulfhydryl proteins that leads to the inactivation of sulfhydryl enzymes and protein denaturation that leads to endoplasmic reticulum stress. The other mechanism is the pro-oxidant activity of RD-derived melanins that leads to oxidative stress resulting from the depletion of antioxidants and the generation of reactive oxygen radicals.
Topics: Animals; Butanols; Humans; Hypopigmentation; Melanocytes; Monophenol Monooxygenase; Reactive Oxygen Species; Skin Lightening Preparations; Ultraviolet Rays
PubMed: 29439519
DOI: 10.3390/ijms19020552 -
Chemosphere Jul 2022Biofuels, such as ethanol and butanol, obtained from carbon monoxide-rich gas or syngas bioconversion (solventogenesis) are an attractive alternative to traditional... (Review)
Review
Biofuels, such as ethanol and butanol, obtained from carbon monoxide-rich gas or syngas bioconversion (solventogenesis) are an attractive alternative to traditional fermentation processes with merits of no competition with food production and sustainability. However, there is a lack of comprehensive understanding of some key process parameters and mechanisms enhancing solventogenesis during the fermentation process. This review provides an overview of the current state of the art of the main influencing factors during the syngas fermentation process catalyzed by acetogenic species as well as undefined mixed cultures. The role of syngas pressure, syngas components, fermentation pH, temperature, trace metals, organic compounds and additional materials is overviewed. As a so far hardly considered approach, thermodynamic calculations of the Gibbs free energy of CO conversion to acetic acid, ethanol, butyric acid and butanol under different CO pressures and pH at 25, 33 and 55 °C are also addressed and reviewed. Strategies for enhancing mass transfer and longer carbon chain solvent production are considered as well.
Topics: 1-Butanol; Acetic Acid; Bioreactors; Butanols; Carbon Monoxide; Clostridium; Ethanol; Fermentation; Thermodynamics
PubMed: 35351479
DOI: 10.1016/j.chemosphere.2022.134425 -
Bioresource Technology Jun 2022In this study, continuous cultivations of C.carboxidivorans to study heterotrophic and mixotrophic conversion of glucose and H, CO, and CO were established. Glucose...
In this study, continuous cultivations of C.carboxidivorans to study heterotrophic and mixotrophic conversion of glucose and H, CO, and CO were established. Glucose fermentations at pH 6 showed a high ratio of alcohol-to-acid production of 2.79 mol mol. While H or CO were not utilized together with glucose, CO feeding drastically increased the combined alcohol titer to 9.1 g l. Specifically, CO enhanced acetate (1.9-fold) and ethanol (1.7-fold) production and triggered chain elongation to butanol (1.5-fold) production but did not change the alcohol:acid ratio. Flux balance analysis showed that CO served both as a carbon and energy source, and CO mixotrophy displayed a carbon and energy efficiency of 45 and 77%, respectively. This study expands the knowledge on physiology and metabolism of C.carboxidivorans and can serve as the starting point for rational engineering and process intensification to establish efficient production of alcohols and acids from carbon waste.
Topics: 1-Butanol; Butanols; Carbon Dioxide; Carbon Monoxide; Clostridium; Ethanol; Fermentation; Glucose
PubMed: 35405210
DOI: 10.1016/j.biortech.2022.127138 -
Molecules (Basel, Switzerland) Nov 2022The ability to predict the behaviour of high-pressure mixtures of carbon dioxide and alcohol is important for industrial purposes. The equilibrium composition of three...
The ability to predict the behaviour of high-pressure mixtures of carbon dioxide and alcohol is important for industrial purposes. The equilibrium composition of three binary carbon dioxide-alcohol systems was measured at temperatures of 313.15 K and 333.15 K and at pressures of up to 100 bar for carbon dioxide-2-propanol, up to 160 bar for carbon dioxide-1-butanol and up to 150 bar for carbon dioxide-2-butanol. Different equilibrium compositions of carbon dioxide in alcohols were observed despite their similar molecular weight ( = 60.100 g mol, = 74.121 g mol and = 74.122 g mol) and place in the functional hydroxyl group (first or second carbon molecule). It is assumed that the differences in the phase equilibria are due to different vapor pressures, polarities and solute-solute interactions.
Topics: 2-Propanol; 1-Butanol; Carbon Dioxide; Ethanol
PubMed: 36500443
DOI: 10.3390/molecules27238352 -
Journal of Traditional Chinese Medicine... Aug 2022To evaluate Sterculia diversifolia stem bark and leaves for phytotoxic, genotoxic and enzymes inhibition potential.
OBJECTIVE
To evaluate Sterculia diversifolia stem bark and leaves for phytotoxic, genotoxic and enzymes inhibition potential.
METHODS
Phytotoxic activity of both stem bark and leaves were screened using Lemna minor. The genotoxic activity of Sterculia diversifolia stem bark and leaves extracts were tested using comet assay protocol while enzyme inhibition activity of crude extract and various fractions of both stem bark and leaves were evaluated using acetyl cholinesterase, lipoxygenase, β-glu-curonidase, urease, xanthine oxidase and carbonic anhydrase.
RESULTS
Phytotoxic activity showed significant results in dose dependant manner in both stem bark (ethyl acetate and n-butanol) and leaves (ethyl acetate, n-butanol and n-hexane) fractions. In genotoxic activity, dichloromethane fraction showed significant activity followed by ethyl acetate fraction. Acetyl cholinesterease inhibitory activity showed significant results in both stem bark and leaves fractions, while significant lipoxygenase inhibition was shown by ethyl acetate, dichloromethane, crude extract and n-hexane fractions of both stem bark and leaves. β-glucuronidase, urease and carbonic anhydrase inhibitory activity showed highly significant results in ethyl acetate fraction of both stem bark and leaves, while xanthine oxidase inhibition was shown by dichloromethane fraction of stem bark and leaves extracts.
CONCLUSIONS
This study emphasizes the important phytotoxic, genotoxic and enzyme inhibition effects of Sterculia diversifolia stem bark and leaves. Hence, it is clear that Sterculia diversifolia stem bark and leaves possess phytotoxic, genotoxic and enzyme inhibitory agents.
Topics: 1-Butanol; Alkaloids; Carbonic Anhydrases; DNA Damage; Humans; Lipoxygenases; Methylene Chloride; Plant Bark; Plant Extracts; Plant Leaves; Urease; Xanthine Oxidase
PubMed: 35848976
DOI: 10.19852/j.cnki.jtcm.2022.04.005 -
Sheng Wu Gong Cheng Xue Bao = Chinese... Dec 2020Consolidated bioprocessing (CBP) is a multi-step process in a bioreactor, which completes hydrolase production, enzymatic hydrolysis, and microbial fermentation. It is... (Review)
Review
Consolidated bioprocessing (CBP) is a multi-step process in a bioreactor, which completes hydrolase production, enzymatic hydrolysis, and microbial fermentation. It is considered to be the most promising process for the production of second-generation biofuels because of its simple steps and low cost. Due to the complexity of lignocellulose degradation and the butanol synthesis pathway, few wild microorganisms can directly utilize lignocellulose to synthesize butanol. With the development of synthetic biology, single-bacterium directly synthesizes butanol using lignocellulose by introducing a butanol synthesis pathway in the cellulolytic Clostridium. However, there are still some problems such as heavy metabolic load of single bacterium and low butanol yield. Co-culture can relieve the metabolic burden of single bacterium through the division of labor in different strains and can further improve the efficiency of butanol synthesis. This review analyzes the recent research progress in the synthesis of biobutanol using lignocellulose by consolidated bioprocessing from both the single-bacterium strategy and co-culture strategy, to provide a reference for the research of butanol and other biofuels.
Topics: 1-Butanol; Biofuels; Butanols; Fermentation; Lignin
PubMed: 33398970
DOI: 10.13345/j.cjb.200199 -
MBio Sep 2014Due to the increasing concerns about limited fossil resources and environmental problems, there has been much interest in developing biofuels from renewable biomass.... (Review)
Review
Due to the increasing concerns about limited fossil resources and environmental problems, there has been much interest in developing biofuels from renewable biomass. Ethanol is currently used as a major biofuel, as it can be easily produced by existing fermentation technology, but it is not the best biofuel due to its low energy density, high vapor pressure, hygroscopy, and incompatibility with current infrastructure. Higher alcohols, including 1-propanol, 1-butanol, isobutanol, 2-methyl-1-butanol, and 3-methyl-1-butanol, which possess fuel properties more similar to those of petroleum-based fuel, have attracted particular interest as alternatives to ethanol. Since microorganisms isolated from nature do not allow production of these alcohols at high enough efficiencies, metabolic engineering has been employed to enhance their production. Here, we review recent advances in metabolic engineering of microorganisms for the production of higher alcohols.
Topics: 1-Butanol; Alcohols; Bacteria; Biofuels; Biotechnology; Butanols; Fermentation; Industrial Microbiology; Metabolic Engineering; Pentanols
PubMed: 25182323
DOI: 10.1128/mBio.01524-14 -
Microbial Biotechnology Feb 2023In the last decades, fermentative production of n-butanol has regained substantial interest mainly owing to its use as drop-in-fuel. The use of lignocellulose as an... (Review)
Review
In the last decades, fermentative production of n-butanol has regained substantial interest mainly owing to its use as drop-in-fuel. The use of lignocellulose as an alternative to traditional acetone-butanol-ethanol fermentation feedstocks (starchy biomass and molasses) can significantly increase the economic competitiveness of biobutanol over production from non-renewable sources (petroleum). However, the low cost of lignocellulose is offset by its high recalcitrance to biodegradation which generally requires chemical-physical pre-treatment and multiple bioreactor-based processes. The development of consolidated processing (i.e., single-pot fermentation) can dramatically reduce lignocellulose fermentation costs and promote its industrial application. Here, strategies for developing microbial strains and consortia that feature both efficient (hemi)cellulose depolymerization and butanol production will be depicted, that is, rational metabolic engineering of native (hemi)cellulolytic or native butanol-producing or other suitable microorganisms; protoplast fusion of (hemi)cellulolytic and butanol-producing strains; and co-culture of (hemi)cellulolytic and butanol-producing microbes. Irrespective of the fermentation feedstock, biobutanol production is inherently limited by the severe toxicity of this solvent that challenges process economic viability. Hence, an overview of strategies for developing butanol hypertolerant strains will be provided.
Topics: Butanols; 1-Butanol; Cellulose; Solvents; Acetone; Metabolic Engineering; Fermentation
PubMed: 36168663
DOI: 10.1111/1751-7915.14148 -
Microbial Cell Factories Sep 2018Coffee silverskin, a by-product from coffee roasting industries, was evaluated as a feedstock for biobutanol production by acetone-butanol-ethanol fermentation. This...
BACKGROUND
Coffee silverskin, a by-product from coffee roasting industries, was evaluated as a feedstock for biobutanol production by acetone-butanol-ethanol fermentation. This lignocellulosic biomass contained approximately 30% total carbohydrates and 30% lignin. Coffee silverskin was subjected to autohydrolysis at 170 °C during 20 min, with a biomass-to-solvent ratio of 20%, and a subsequent enzymatic hydrolysis with commercial enzymes in order to release simple sugars. The fermentability of the hydrolysate was assessed with four solventogenic strains from the genus Clostridium. In addition, fermentation conditions were optimised via response surface methodology to improve butanol concentration in the final broth.
RESULTS
The coffee silverskin hydrolysate contained 34.39 ± 2.61 g/L total sugars, which represents a sugar recovery of 34 ± 3%. It was verified that this hydrolysate was fermentable without the need of any detoxification method and that C. beijerinckii CECT 508 was the most efficient strain for butanol production, attaining final values of 4.14 ± 0.21 g/L acetone, 7.02 ± 0.27 g/L butanol and 0.25 ± 0.01 g/L ethanol, consuming 76.5 ± 0.8% sugars and reaching a butanol yield of 0.269 ± 0.008 g/g under optimal conditions.
CONCLUSIONS
Coffee silverskin could be an adequate feedstock for butanol production in biorefineries. When working with complex matrices like lignocellulosic biomass, it is essential to select an adequate bacterial strain and to optimize its fermentation conditions (such as pH, temperature or CaCO concentration).
Topics: Butanols; Carbohydrates; Coffee; Fermentation
PubMed: 30261894
DOI: 10.1186/s12934-018-1002-z -
Microbial Cell Factories Mar 2020Owing to the increase in energy consumption, fossil fuel resources are gradually depleting which has led to the growing environmental concerns; therefore, scientists are... (Review)
Review
BACKGROUND
Owing to the increase in energy consumption, fossil fuel resources are gradually depleting which has led to the growing environmental concerns; therefore, scientists are being urged to produce sustainable and ecofriendly fuels. Thus, there is a growing interest in the generation of biofuels from renewable energy resources using microbial fermentation.
MAIN TEXT
Butanol is a promising biofuel that can substitute for gasoline; unfortunately, natural microorganisms pose challenges for the economical production of 1-butanol at an industrial scale. The availability of genetic and molecular tools to engineer existing native pathways or create synthetic pathways have made non-native hosts a good choice for the production of 1-butanol from renewable resources. Non-native hosts have several distinct advantages, including using of cost-efficient feedstock, solvent tolerant and reduction of contamination risk. Therefore, engineering non-native hosts to produce biofuels is a promising approach towards achieving sustainability. This paper reviews the currently employed strategies and synthetic biology approaches used to produce 1-butanol in non-native hosts over the past few years. In addition, current challenges faced in using non-native hosts and the possible solutions that can help improve 1-butanol production are also discussed.
CONCLUSION
Non-native organisms have the potential to realize commercial production of 1- butanol from renewable resources. Future research should focus on substrate utilization, cofactor imbalance, and promoter selection to boost 1-butanol production in non-native hosts. Moreover, the application of robust genetic engineering approaches is required for metabolic engineering of microorganisms to make them industrially feasible for 1-butanol production.
Topics: 1-Butanol; Genetic Engineering
PubMed: 32220254
DOI: 10.1186/s12934-020-01337-w