Butanol

Solvent Production

N. Qureshi , in Encyclopedia of Microbiology (Third Edition), 2009

Introduction

Butanol production is one of the oldest fermentation processes (acetone–butanol–ethanol; ABE, or AB, or solvents) employed for commercial production of a chemical to benefit mankind. Production of butanol was discovered by Pasteur in 1861. Its production by fermentation comes second to ethanol in importance and history as there were commercial plants that were operational during World War I and World War II. It should be noted that after the World War II (between 1950s and 1960s), butanol fermentation could not compete with petrochemically derived butanol due to the development of petrochemical industries. The last bio-based butanol plant ceased operations in the early 1980s in South Africa due to shortage of molasses, the feedstock for this fermentation, brought on by drought, and the high cost of recovery. Butanol can be produced by fermentation employing a number of microorganisms such as Clostridium acetobutylicum and Clostridium beijerinckii. The typical ratio of ABE in the final product is usually 3:6:1 with maximum concentration of total solvents (ABE) being 20   g   l−1 when using traditional strains and traditional batch fermentation process. Recovery of butanol from such a dilute product is cost-intensive when recovered by distillation (traditional technology).

Currently, butanol is produced using either the oxo process from propylene (with H2 and CO over a rhodium catalyst) or the aldol process starting from acetaldehyde. Acetone (a coproduct of the butanol fermentation) is produced either by the cumene hydroxide process or by the catalytic dehydration of isopropanol. These chemical synthetic routes have proven to be economically superior as compared to the fermentation-based processes. Since 1990, production of butanol in the United States has been constant (1.20   ×   109  kg year−1), while worldwide production has fluctuated slightly. The worldwide annual production of acetone and butanol has been of the order of 2.1   ×   109 and 2.5   ×   109  kg respectively. Butanol has numerous applications as an automotive fuel and in the chemical industry. When used as an automotive fuel, butanol contributes to clean air by reducing emissions such as unburned hydrocarbons in the tailpipe exhaust. As compared to ethanol's research and motor octane values of 111 and 92, these values for butanol are 113 and 94, respectively. The heat of vaporization for butanol is 141.3   kcal   kg−1 as compared to 204.1   kcal   kg−1 for ethanol. In addition, the high boiling point (118   °C) and lower vapor pressure for butanol may enhance cold starting. There are various other properties that make butanol a superior fuel. It has 30% higher energy content per liter as compared to ethanol and is less miscible with water and more miscible with gasoline and diesel fuel.

Recently, there has been renewed interest in fermentation-derived butanol both as a potential fuel and as a chemical feedstock. Continuously rising prices and increased dependence on foreign fuel have been major driving factors for the increased interest in butanol fermentation as butanol could potentially be used as a motor fuel replacement. Increased oil prices in 1973 resulted in a revival of research activities on a number of fermentations, including ethanol and butanol, with a long-range view toward becoming less dependent on foreign oil. As a consequence, research was focused on developing technologies to produce fuels and chemicals from readily available and abundant renewable agricultural resources. As a result, some degree of success was achieved in numerous countries when bioconversion programs involving alcohol fuel production were examined. Brazil had introduced its ethanol production program in 1977 followed by the United States. Soon after this, low oil prices were restored. However, constant conflicts in the oil supply regions and rising oil prices have reminded the world that alternate energy sources should be sought for future energy independence. With this view, United States has undertaken various energy initiatives including replacing 30% of transportation fuel by ethanol by 2030. In 2006, approximately 14.62   ×   109  kg (4.7 billion gallons) of ethanol was produced from corn (in the United States), which is approximately 3% of total fuel consumption (435.5   ×   109  kg or 140 billion gallons) in the United States. It is anticipated that up to 65.3   ×   109  kg (21 billion gallons) (15%) of ethanol can be produced annually from corn without affecting food and feed supply. Further increase in ethanol production would likely require the use of cellulosic biomass such as corn fiber (CF), corn stover, wheat straw (WS), or energy crops like switch grass and miscanthus.

Intensive research efforts were focused on this fermentation during early 1980s with various objectives to make butanol fermentation economically competitive. As a result of research intensification, a number of problems associated with this fermentation were identified including cost-ineffective recovery of butanol by traditional recovery technology (distillation), low butanol concentration in batch reactor (<20   g   l−1), and low productivity (<0.50   g   l−1  h−1) due to inhibition caused by butanol. An account of some of these problems and their possible solutions has been documented in literature. Because of this research, highly productive continuous reactor systems and butanol recovery technologies were developed not to recover butanol economically but to relieve butanol inhibition in the reactor systems. This gave birth to 'integrated' technologies where production of butanol was combined with product recovery. Combination of production and recovery technologies resulted in the use of higher amount of substrates, improvement in productivities, and achieving a more concentrated product stream to be presented for further recovery and purification. These research and development activities were aimed at use of substrates such as whey permeate (from dairy industry) and glucose (from wet milling corn industry).

In author's opinion, research activities slowed during 1990s due to reduction or stabilization of gasoline prices. The years 2002–7 once again witnessed sharp increases in gasoline prices, which prompted a considerable increase in research activities in this fermentation, in particular, bioconversion of economically available lignocellulosic biomass to butanol. Substrates such as CF and WS have been used to produce butanol. Although productive reactors were not used for these applications, some recovery technologies have been successfully integrated for production of butanol from some of these agricultural residues. In this article, the author's aim is to give the latest information to the reader on production of these biofuels, in particular butanol, and various process technologies such as recovery of butanol using adsorption, pervaporation, liquid–liquid extraction, and gas stripping. Process integration is a fascinating technology that allows use of concentrated sugar solutions, thus reducing process streams and economizing production of butanol from agricultural residues. As a result of recent technological developments in butanol fermentation and recovery, Dupont (United States) and British Petroleum (United Kingdom) have announced their plans to commercialize butanol production from bio-based substrates.

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Industrial Biotechnology and Commodity Products

H. Dong , ... Y. Li , in Comprehensive Biotechnology (Second Edition), 2011

3.08.7.3 Strain Improvement and In Situ Recovery Technology

Butanol toxicity severely hampers the improvement of industrial butanol production. Therefore, many efforts have been made to solve the problem by enhancing the tolerance of industrial butanol-producing strains and continuous or in situ removal of butanol away from the fermentation broth.

For strain improvement, some advances have been achieved by classical methods such as recursive mutagenesis. Several mutants with a butanol tolerance of 20   g   l−1 have been successfully isolated, which exhibit stable butanol tolerance and butanol-producing capacity. While the rational strain improvement using recombinant DNA technology is restricted significantly due to our limited knowledge about the complex butanol toxicity mechanism and the difficulty of Clostridium genetic manipulation, a few successful cases have been documented; for example, the overexpression of GroESL genes definitely increased butanol tolerance of C. acetobutylicum.

Some strategies and technologies have also been developed to achieve in situ recovery of butanol from AB fermentation broth. Comparing with conventional distillation technology performed at a high temperature, these novel alternatives can perform the product recovery process simultaneously with fermentation, thus with decreased stress for the butanol-producing cells. In general, these new in situ recovery technologies can be divided into four categories: gas stripping, liquid–liquid extraction, adsorption, and membrane-based technologies including pervaporation, reverse osmosis, and perextraction.

Based on the overall consideration of technological, economical, and environmental factors, gas stripping is usually believed to be the most promising in situ recovery technology for industrial application. In the gas stripping process, nitrogen or fermentation gases (CO2 and H2) are bubbled through the fermentation broth by a sparger, and the bubbles will vibrate the surrounding liquid, resulting in the removal of butanol from the fermentation broth. The gas mixture passes through a condenser, in which the vaporized butanol is condensed and stripped from the gases. Once butanol is condensed, the gases will be recycled back to the bioreactor to strip more butanol. Gas stripping technology has also been successfully integrated with fed-batch fermentation to simultaneously decrease butanol toxicity and substrate inhibition. To obtain satisfying recovery efficiency, factors of gas stripping such as gas recycle rate and bubble size should be optimized.

Liquid–liquid extraction is another efficient recovery technology that can remove butanol from the fermentation broth in situ. This method is built on the principle that solubilities of chemicals vary in different solutions, and distribution coefficients of the chemicals vary between two immiscible phases. In this case, when a water-insoluble organic extractant is mixed with the liquid fermentation broth, butanol will be selectively concentrated in the organic phase because it is more soluble than in the aqueous phase. Taking advantage of the immiscibility between the two phases, extractant containing butanol can be simply separated from the fermentation broth without removing substrates, water, nutrients, or cells. For liquid–liquid extraction, the selected extractants should meet certain requirements, including low toxicity to butanol-producing cells, high distribution coefficient for butanol, immiscibility with the fermentation broth, low cost, and high availability. The most commonly applied extractants are decanol and oleyl alcohol, and, sometimes, mixed extractants are employed to balance the conflict between low toxicity and high distribution coefficient. This technology can remove butanol from fermentation efficiently; however, the high cost of extractants and instruments restricts its application [13].

Adsorption technology is designed on the principle that solvents can be adsorbed by some materials (adsorbents) and released at special conditions such as high temperature. The process of butanol absorption can decrease the concentration of butanol in the broth, while the final release will form a final butanol solution with high concentration. Various materials have been used as absorbents for recovery of butanol, such as silicalite and ion-exchange resins, and silicalite is most widely used for its significant hydrophobicity, which makes it possible to absorb selectively small organic molecules and to release them at 150   °C. However, the capacity and selectivity for butanol are still quite low currently, which, together with the high price of absorbents, form great obstacles to promote this technology.

The other three in situ product recovery technologies applied in butanol production all contribute to the removal of butanol through selective membrane-associated systems. For pervaporation, a liquid or solid membrane is placed in contact with the fermentation broth, and the solvents selectively diffuse across the membrane as vapors, leaving behind nutrients, substrate, and the microbial cells. The compounds selectively removed will be recovered by condensation to keep the concentrate and vapor pressure gradients, allowing the diffusion to continue. During reverse osmosis process, suspended microbial cells should be restored with hollow-fiber ultra filter as a pretreatment. Sequentially, pretreated fermentation broth will be concentrated through a semipermeable membrane allowing only water molecules to pass. Finally, the dewatered fermentation will be further distilled to get butanol with higher purity. Perextraction can be considered an advanced liquid–liquid extraction with a membrane placed between the extractant and the fermentation broth. Butanol can diffuse into extractant phase from the fermentation broth indirectly through the semipermeable membrane, thus greatly reducing the toxicity of organic extractants to the microbial cells. In summary, the separating efficiencies of all these membrane-based recovery technologies depend on the selectivity for butanol and the flux rate, and all of them tend to be influenced by the possible clogging and fouling problems.

All the above-mentioned procedures can achieve in situ butanol recovery so that the traditional problem of butanol toxicity to microbial cells can be partially solved, but neither of them can be considered as a perfect solution, as different obstacles restrict their wide application. The decision to choose the appropriate recovery technology should be made based on the overall analyses of fermentation performance, ecological factors, environmental factors, and so on.

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Advances in Applied Microbiology

Oscar Tirado-Acevedo , ... Amy M. Grunden , in Advances in Applied Microbiology, 2010

D Butanol from syngas

Butanol, like ethanol, can be produced from fermentable sugars, synthesis gas, and glycerol. Butanol has a number of notable qualities that make it a suitable alternative fuel. Its energy content is 30% more than ethanol ( Qureshi and Ezeji, 2008). It can be mixed with gasoline in any proportion or be used as the sole fuel component (100% butanol) in unmodified car engines (Ramey, 2007). It carries less water and, therefore, it can be transported through existing gasoline pipelines (Dürre, 2007). Reports of biological butanol formation date back to Louis Pasteur. He reported an alcohol product from a clostridial culture (Dürre, 2007). The ABE fermentation was essential during World War I. Acetone was needed to prepare munitions, and it was in great shortage at the time. Production of acetone by fermentation meant a constant supply of acetone to Britain and its allies (Dürre, 2007). C. acetobutylicum has been the model organism for research in ABE fermentation from sugars, but other species have also been extensively investigated. Some of the most studied are Clostridium beijerinckii, Clostridium saccharoperbutylacetonicum, and Clostridium saccharobutylicum. Butyribacterium methylotrophicum is an anaerobe capable of using 1-carbon compounds such as CO2 (in the presence of H2), CH4, and formate as carbon sources in addition to fermentable substrates like glucose, sucrose, and glycerol (Zeikus et al., 1980). It also possesses the advantageous ability to produce butanol from synthesis gas (Grethlein et al., 1990; Lynd et al., 1982; Zeikus et al., 1980). It is one of the most versatile CO-utilizing bacteria (Grethlein et al., 1991). Other fermentation products are ethanol, acetate, and butyrate. The first attempts at investigating this strain for butanol production from CO yielded concentrations of 1.4   g/L (Worden et al., 1991). After some changes in fermentation set-up, such as operation at pH 5.5 and continuous cell cycle, butanol production from CO was improved by more than 200% (Grethlein et al., 1991). Nevertheless, with classic ABE strains producing butanol at more than 400   g/L (Lee et al., 2008b), B. methylotrophicum is not yet a contender for commercial biobutanol production. Another interesting, but less studied strain for butanol production is C. carboxidivorans P7. Being able to produce up to four times more ethanol than butanol from CO or producer gas, this strain has mostly been studied for its ethanol production capabilities (Section IV.B) (Datar et al., 2004; Liou et al., 2005; Rajagopalan et al., 2002).

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Biofuels

L.G. Roberts , T.J. Patterson , in Encyclopedia of Toxicology (Third Edition), 2014

Background

Biobutanol is butanol produced by fermentation from a biomass feedstock. The production process can influence the isomer of butanol that is produced. Currently, n-butanol and isobutanol are the two isomers likely for use as a biofuel. Another isomer, t-butanol, is unlikely to be used as a fuel due to much slower environmental degradation. Biobutanol has qualities of both a fuel and an oxygenate for blends with gasoline in spark-ignition engines.

Toxicity data noted below are for butanol. As the original feedstock was often not specified in the literature, the term butanol instead of biobutanol has generally been utilized.

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Emerging Trends of Microorganism in the Production of Alternative Energy

Golla Ramanjaneyulu , Bontha Rajasekhar Reddy , in Recent Developments in Applied Microbiology and Biochemistry, 2019

21.3.3 Butanol

Butanol is another important compound produced by microorganisms that can be utilized as a fuel or fuel component. Because of the length of butanol's chain, it is easier to mix with higher hydrocarbons, including gasoline. Additionally, it has another advantage with respect to ethanol that butanol is substantially less corrosive and volatile and also has lower water solubility. Among the four isomers of butanol (n-butanol (butan-1-ol), sec-butanol (butan-2-ol), isobutanol (2-methylpropan-1-ol), and tert-butanol (2-methylpropan-2-ol)), only n-butanol, sec-butanol, and isobutanol are produced by microbes. Although tert-butanol is only received in refinery, others can be obtained through microbial fermentation. Only some of the strains are reported to ferment biomass to butanol, and yeast is not capable of producing butanol.

In biological procedures, butanol can be delivered from an indistinguishable biomass from ethanol. As a substrate, it can be utilized by plants containing carbohydrates, for instance, sugarcane, sugar beets, corn, and wheat. More interest is centered on feedstocks that do not compete for food, for example, Miscanthus, switchgrass, wood and crop waste, algae biomass, and food processing waste. The principal procedure that was employed to get n-butanol was acetone-butanol-ethanol (ABE) fermentation. The products of ABE maturation are solvents, for example, acetone, butanol, and ethanol in the proportion of 3:6:1. In this procedure, strains of anaerobic microbes from the class Clostridium are included. The best-studied and generally utilized species is C. acetobutylicum; other species, for example, C. beijerinckii, C. aurantibutyricum, or C. tetanomorphum, likewise have been previously reported to give higher butanol yield (Jones and Woods, 1986).

The ABE aging procedure is more intricate than a generation of ethanol. There are two fundamental phases of fermentation. In the first phase (acidogenesis stage), metabolites like acetone, butyrate, hydrogen, and carbon dioxide are major products produced. This reduces the pH of the growth medium. In the next stage (solventogenesis), microbial metabolism is altered to generate butanol, acetone, ethanol, H2, and CO2; interestingly, when the concentration of glucose is less than some threshold levels, Clostridium strains produced just acids. Other than glycolytic reactions in the metabolic pathway for the production of acids and solvents, the reaction between pyruvate and butyryl-CoA is predominant. During acidogenesis, acetone is delivered from acetyl-CoA and butyrate from butyryl-CoA. However, during solventogenesis, both acetyl-CoA and butyryl-CoA are intermediates for the production of ethanol and butanol. Acetyl-CoA is the key intermediate for the synthesis of acetone. A few strains of Clostridia, for instance, C. beijerinckii and C. aurantibutyricum, reduce acetone to isopropanol at later stages (Leja et al., 2014). Concentration of alcohol cannot surpass 12   g for each liter of a fermentation medium. Higher amount of n-butanol inhibits alcohol production by bacterial cells. Nonetheless, little enhancements have been made for n-butanol levels to reach up to 20   g/L of medium (Nigam and Singh, 2011). The formation of by-products, primarily acetone in ABE fermentation, essentially influences the solvent yield and downstream separation process. Wang et al. (2018) improved isopropanol-butanol-ethanol mixture production through the manipulation of intracellular NAD(P)H levels in recombinant C. acetobutylicum XY16.

One of the potential solutions for overcoming these impediments is to develop a simplified pathway in vitro utilizing a limited number of enzymes through an approach known as cell-free metabolic engineering (CFME). CFME is a cell-free biosystem that employs in vitro ensembles of catalytic proteins prepared from purified enzymes or crude lysates of cells to produce product of interest (Dudley et al., 2015). It might effectively dispose cell-associated process barriers, for example, substrate or product toxicity, intracellular flux balance that brings about low target product yield and unwanted by-products, and product excretion constraints by intracellular transport barriers (Dudley et al., 2015). Zhang et al. (2017) designed a totally simulated reaction pathway for upgrading ethanol to acetoin, 2,3-butanediol, and 2-butanol in a cell-free biosystem composed of ethanol dehydrogenase, formolase, 2,3-butanediol dehydrogenase, dioldehydratase, and NADH oxidase. This strategy resulted in the production of acetoin, 2,3-butanediol, and 2-butanol at 88.78% and 88.28% under optimized conditions and 27.25% of the theoretical yield from 100   mM ethanol, respectively. A few investigations on 2-butanol production have been led by extending the terminal product of 2,3-butanediol or acetolactate utilizing metabolic engineering techniques (Oh et al., 2014; Chen et al., 2015). The final accumulation of 2-butanol might have been still very much lower due to metabolic flux limitations and its toxicity on microbial cells. Extensive metabolic engineering for solventogenic Clostridia could be accomplished by means of productive genetic tools, for example, an in vivo methylation system to avoid an inherent genetic restriction system of Clostridia to segregate stable plasmids and viable gene knockout (KO) system (Lütke-Eversloh, 2014). Lesiak et al. (2014) developed in vivo methylation system for C. acetobutylicum ATCC 824 and C. saccharobutylicum. In addition, several shuttle vectors that can reproduce in both Clostridia and E. coli have been developed (Leblanc and Lee, 1984; Purdy et al., 2002; Yu et al., 2012; Lee et al., 2015a,b). Among them, plasmids such as pIM1, pMTL500E, and pLK1-MCS holding pIM13, pAMβ1, and pUB110 replicons, respectively, stably reproduce in C. acetobutylicum (Lee et al., 2015a,b).

After successful introduction of secondary alcohol dehydrogenase into C. acetobutylicum XY16, the recombinant XY16 could completely eliminate acetone formation and convert it into isopropanol, demonstrating a great possibility for industrial-scale production for IBE mixtures. Especially, pH could significantly improve final solvent titer through regulation of NADH and NADPH levels in vivo. At optimum pH level of 4.8, total IBE production was significantly increased from 3.88 to 16.09   g/L with a final concentration of 9.97, 4.98, and 1.14   g/L of butanol, isopropanol, and ethanol, respectively. Meanwhile, NADH and NADPH levels were maintained at optimal levels for IBE formation compared with the control one without pH adjustment. In view of this, the possibility of modulating NAD(P)H is a productive approach to enhance IBE production. Chen et al. (2018) established a hybrid procedure that integrated fermentation, pervaporation, and esterification pointing to improve the economic feasibility of the conventional ABE fermentation process by using Candida sp. 99–125 as a fuel cell catalyst. The novel integration methodology gives a promising technique to in situ upgrading ABE products.

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Flammable and Combustible Liquids

Eric Stauffer , ... Reta Newman , in Fire Debris Analysis, 2008

7.6.1 Principle

Petroleum products must meet a variety of specifications depending on their end use. Manufacturers of products that utilize petroleum-based solvents may require a minimal level of sulfur or aromatic content or a desired flash point, depending on their specific application. Some applications require ease of vaporization, and products designed with this scope have a relatively high vapor pressure as well as a relatively low flash point. For other applications however, it is often best to have a flash point in the combustible range, rather than the flammable range. This eases shipping and transportation requirements, resulting in lower costs. Products designed as cleaning solvents or degreasers require a higher solvating power, often measured by the kauri-butanol value, in order to effectively dissolve materials. Other products, such as those used in indoor applications (for example, oils for liquid candles) have different requirements; generally they need to be low-odor and low smoke products. Gasoline and transportation fuels have their own requirements, which involve specific performance parameters, as well as specific vapor pressure, sulfur content, aromatic content, and so on. In order to test all these parameters, a wide variety of tests exist, a few of which are presented in the following subsections.

Kauri-Butanol Value

The kauri-butanol value, abbreviated Kb, is defined as the volume of solvent required to reach the cloud point of the solution when added to 20 g of a solution of 20% w/w kauri resin in n-butanol. Kauri resin is extracted from the kauri tree, found in New Zealand. ASTM International has developed the standard D 1133-04 for determining Kb value [11].

The Kb value often is used to evaluate the dissolving ability of hydrocarbons and the aromaticity of solvents. The Kb value usually increases in the following sequence: aliphatics < cycloalkanes < aromatics. The higher the Kb value, the stronger the dissolving power of the solvent. A mild cleaner will have a relatively low value, whereas a powerful degreaser will have a significantly higher Kb value. Examples of the Kb values for some common solvents are shown in Table 7-2 [12].

Table 7-2. Kauri-butanol value

Solvent Kb value
n-Octane 24.5
n-Heptane 25.4
n-Hexane 26.5
n-Pentane 33.8
Cyclohexane 54.3
d-Limonene 68
Xylenes 95
Toluene 105
Trichloroethylene 129
Dichloromethane 136

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Biofuel and chemical production from carbon one industry flux gas by acetogenic bacteria

Yi-Xuan Fan , ... Fu-Li Li , in Advances in Applied Microbiology, 2021

5.2 Alcohols

Ethanol and butanol are the most common products of syngas fermentation, and by introducing other metabolic pathways, the acetone-butanol-ethanol (ABE), hexanol-butanol-ethanol (HBE), as well as isopropanol-butanol-ethanol (IBE) fermentation industry are formed. The metabolic mechanism is described in Fig. 7.

Fig. 7

Fig. 7. Acetyl-CoA metabolism for the production of carboxylic acids, alcohols.

 Reproduced from Zhang, L., Zhao, R., Jia, D. C., Jiang, W. H., &amp; Gu, Y. (2020). Engineering Clostridium ljungdahlii as the gas-fermenting cell factory for the production of biofuels and biochemicals. Current Opinion in Chemical Biology, 59, 54–61. doi:https://doi.org/10.1016/j.cbpa.2020.04.010.

Clostridium aceticum is the first discovered acetogenic strain with acetic acid as the end product which was not supposed to produce high amount of ethanol. While, due to the natural acidification in the early solventogenesis stage, C. aceticum produced up to 5.6   g/L ethanol (Arslan, Bayar, Nalakath Abubackar, Veiga, & Kennes, 2019). C. autoethanogenum mainly produces acetate, but its co-culture with C. kluyveri promoted high yield of chain elongated acids from syngas (Diender et al., 2019). A genome-shuffled Clostridium ragsdalei (DSM 15248) exhibited excellent ethanol production of 14.92   ±   0.75   g/L (Patankar et al., 2021).     Alkalibaculum bacchi strain CP15 can only produce ethanol, but the co-culture with propionic acid producer Clostridium propionicum generated ethanol, n-propanol and n-butanol from syngas (Liu et al., 2014).

Others alcohols, propanol and isopropanol, are rarely generated. As the simplest secondary alcohols, they are widely used as intermediates in pharmaceutical and chemical materials, or solvents for cosmetics, plastics, spices, and so on. They are usually produced by some glucose-dependent strains, such C. beijerinckii, P. acidipropionici, and C. neopropionicum (Walther & Francois, 2016), which cannot utilize syngas as electron donor. While, the engineered Escherichia coli MG1655, embracing isopropanol biosynthesis pathway with gene combination of adh from Clostridium beijerinckii, atoDA from E. coli, as well as thl and adc from Clostridium acetobutylicum, were designed to produce isopropanol from the acetate produced by syngas fermentation strains, C. ljungdahlii and Moorella thermoaceticathe, which has achieved the highest concentration and yield of 24.5   mM and 0.56   mol/mol (Yang et al., 2020). A mixed culture of Alkalibaculum bacchi strain CP15 (56%) and Clostridium propionicum (34%), using corn steep liquor instead of yeast extract, produced 8   g/L ethanol, 6   g/L propanol and 1   g/L butanol. C. ljungdahlii can also convert acetoin to 2,3-butanediol. The candidate gene CLJU c23220 encoding putative Zn2+-dependent alcohol dehydrogenase in C. ljungdahlii was identified by introducing to E. coli and C. beijerinckii with the production of 2,3-butanediol (Tan, Liu, Liu, & Li, 2015).

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Endosome Signaling Part B

Tania Maffucci , Marco Falasca , in Methods in Enzymology, 2014

3.1.4 Glycerophosphoinositide extraction

A mix butanol/petroleum ether/ethyl acetate is used to separate the organic phase containing the acyl chains from the aqueous phase containing the [ 3H]glycerophosphoinositides (gPIs).

1.

Prepare a mix C4H9OH:C6H14:C4H8O2 (20:4:1).

2.

Add 600   μl mix/sample.

3.

Add 500   μl of distilled water/sample.

4.

Vortex.

5.

Centrifuge (2500   rpm, 1   min, room temperature).

6.

Discard upper phase.

7.

Add 600   μl mix/sample.

8.

Vortex.

9.

Centrifuge (2500   rpm, 1   min, room temperature).

10.

Discard upper phase.

11.

Dry samples (speed vac).

12.

Resuspend pellet of gPIs in 600   μl H2O.

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CLOSTRIDIUM | Clostridium acetobutylicum

H. Janssen , ... H.P. Blaschek , in Encyclopedia of Food Microbiology (Second Edition), 2014

History of the ABE Fermentation Industry

The production of butanol and acetone is closely linked to the name of Chaim Weizmann, the first president of Israel. Although the idea to exploit this fermentation economically was first realized by others, he isolated the first efficient strains of C. acetobutylicum in 1912, organized a research group, and was involved in founding the first successful solvent factories in southern England in 1916. One year earlier a patent was issued, which was the very first that covered a biological process. Originally conceived for the production of butadiene, the monomer for synthetic rubber, interest shifted to acetone during World War I and butanol became a useless by-product. Acetone was required in large amounts as a colloidal solvent for the production of explosive cordite. The feedstocks for the fermentation were molasses or maize meal, but other grain products also were used. After the war, the process temporarily was abandoned, but very soon a new application for butanol was found. Butanol and its ester butyl acetate are ideal solvents for the nitrocellulose lacquers that were required by the expanding automobile industry. Thus, the stored butanol was salvaged; process facilities that had been erected in England, the United States, and Canada at the end of the war were reinstalled; and new factories were built. At the peak of the development, in 1927, a total of 148 fermenters, each with a capacity of 190 m3, were operating in two US plants, producing about 100 tons of solvents per day in empiric batch fermentations.

At the beginning of the 1930s, concomitant with the expiration of C. Weizmann's patent in 1936, a large number of commercial production plants in different countries were established. Furthermore, at this time, there was a glut of molasses, and strains of C. acetobutylicum were isolated and developed that were able to convert higher amounts of carbohydrate and produce higher concentrations of solvents than obtained from maize (i.e., 6.5% of sugar to 1.8–2.2% of solvents in contrast to 1.2–1.8% with starchy materials). During World War II, the butanol–acetone fermentation capacities in the United States (e.g., in Philadelphia), France (e.g., in Usines de Melle), and England expanded again to fulfill the increased demand for acetone used for the manufacture of munitions, partly by commandeering alcohol distilleries. After 1945, the fraction of butanol and in particular acetone that was produced by fermentation declined progressively because some of the companies shifted to antibiotic production. Nevertheless, a few small facilities survived. The last factory in the Western Hemisphere, South Africa, closed in 1983, whereas in Brazil, butanol production plants still are in operation.

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Advances in Applied Microbiology

Owen P. Ward , Ajay Singh , in Advances in Applied Microbiology, 2002

B ACETONE–BUTANOL

The acetone–butanol process, developed during World War I, was successfully operated for many years. Indeed, it was the second largest fermentation process in first half of twentieth century, producing acetone for war-related activities and butanol for the lacquer industry. Currently, petroleum-based products have largely replaced these fermentation processes. Nevertheless, a production facility was operated until recently by National Chemical Products, South Africa, where petroleum was scarce due to the international embargo. The process is reported to be still operating in China (Durre, 1998). The main fermentation strains are Clostridium acetobutylicum and C. beijerinckii. The batch process, using starch or molasses as substrate, is followed by distillation. Barriers to its commercial viability include high substrate cost, low product concentration (20   g/liter) due to product toxicity, and high product recovery cost (distillation).

Interest in reviving the acetone–butanol process has gained momentum with increased knowledge of strain physiology and genetics, ability to use cheaper substrates (like whey and agricultural byproducts), and improvements in product recovery (Maddox et al., 1993; Woods, 1995; Girbal and Soucaille, 1998).

Clostridia cannot degrade lignocellulose, so therefore physicochemical or enzymatic pretreatment is required. One approach involves simultaneous saccharification/fermentation systems by co-cultures of C. cellulolyticum or C. thermocellum and C. acetobutylicum, or use of cellulases plus C. acetobutylicum. A second approach involves using genetically engineering to create solvent-producing strains that simultaneously produce cellulases: by cloning the cellulases of C. cellulolyticum or C. thermocellum into C. acetobutylicum or C. beijerinckii (Minton et al., 1993; Kim et al., 1994). A third approach aims at increasing solvent production by other genetic manipulations and efforts to do this have shown some promise (Green and Bennet, 1998; Nair et al., 1999; Parekh et al., 1999).

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