Fermentation Of Simple Sugars Research Articles

Safety evaluation of the food additive steviol glycosides, predominantly Rebaudioside M, produced by fermentation using Yarrowia lipolyticaVRM.

The EFSA Panel on Food Additive and Flavourings (FAF Panel) provides a scientific opinion on the safety of a new process to produce steviol glycosides by fermentation of simple sugars using a genetically modified strain of Yarrowia lipolytica (named Y. lipolytica VRM). The manufacturing process may result in impurities different from those that may be present in the other steviol glycosides E 960a-d, therefore the Panel concluded that separate specifications are required for the food additive produced as described in the current application. Viable cells and DNA from the production strain are not present in the final product. The Panel considered that the demonstration of the absence of kaurenoic acid in the proposed food additive, using a method with a limit of detection (LOD) of 0.3 mg/kg, is adequate to dispel the concerns for potential genotoxicity. Given that all steviol glycosides follow the same metabolic pathways, the Panel considered that the current steviol glycosides would fall within the same group of substances. Therefore, the Panel considered that the already existing data on rebaudioside M and structurally related steviol glycosides are sufficient, and a similar metabolic fate and toxicity is expected for the food additive. The results from the bacterial reverse mutation assay and the invitro micronucleus assay were negative and indicated absence of genotoxicity from the food additive. The existing acceptable daily intake (ADI) of 4 mg/kg body weight (bw) per day, expressed as steviol equivalents, was considered to be applicable to the proposed food additive. The Panel concluded that there is no safety concern for steviol glycosides, predominantly Rebaudioside M, produced by fermentation using Y. lipolytica VRM, to be used as a food additive at the proposed uses and use levels.

Virtual investigation of the biomass conversion efficiency of three Streptomyces species

Global worries about the gradual depletion of the non-renewable fossil fuel reserves, as well as the problem of environmental pollution, and global warming have prompted researchers to opt for more sustainable and environmentally friendly solutions. Converting biomass to bioethanol is a cost effective and inexpensive alternative to produce energy. The lytic polysaccharide monooxygenase (LPMO) enzyme of microbial origin represents an ideal solution because of their catalytic potential for the cleavage of the cellulosic biomass and the production of simple fermentable sugars. Here, we have described the 3D structures, the molecular functioning, as well as the cellulosic biomass conversion efficiency of three LPMOs belonging to three species of Streptomyces, S. albidoflavus, S. flaveus, and S. griseus. Analysis of the conserved domains of the amino acid sequences showed that the three enzymes belong to the LPMO-10 family and include an LPMO domain and a carbohydrate-binding domain. The enzyme of the species S. griseus further comprises two cellulose binding domain and cellulase/cellobiase CelA1 (Carbohydrate transport and metabolism) domain. Homology modeling of the 3D structures of the three enzymes was carried out by the SwissModel program, the models are then checked and validated. The analysis of the interactions at the active site level of the three modeled LPMOs showed the presence of conserved amino acids in all the studied enzymes, specially the His-His brace located around the copper ion. The result of the molecular docking with the cellotetraose substrate shows very close binding energies for the three LPMOs (-5.5 kcal/mol for S. griseus, and −5.3 kcal/mol for S. albidoflavus and S. flaveus) indicating the same affinities of these enzymes to the cellulosic substrates. The visualization of the interactions of cellotetraose within the catalytic sites of the enzymes showed the involvement of the amino acids His, Ala, Trp, Tyr, Phe, and Glu, which are well conserved in the two LPMOs of S. griseus and S. albidoflavus species suggesting a C1 oxidizing activity, whereas for the LPMO of S. flaveus, the Phe and Glu are replaced by Tyr and Gln, respectively suggesting a C1/C4 oxidizing AA10. The molecular information obtained during this study confirms the cellulose degradation potential of Streptomyces LPMOs, as well as their different modes of cellulose oxidation and provides strong evidence of the interest of these enzymes in the biomass conversion.

Fermentable carbohydrate metabolism in maguey mezcalero potosino (Agave salmiana): HPLC characterization and evaluation

The maguey mezcalero potosino (Agave salmiana) is a natural resource of great regional importance, used for the manufacture of mezcal and other alcoholic beverages by fermentation of simple sugars and sugars released by fructans hydrolysis. For this, only the stem and base of leaves is used, which results on wasting the other sections that represent up to 40% of weight of the complete plant. The objective of this study was to identify and quantify the fermentable carbohydrates present in raw and hydrolysed juices of the stem and four sections of the whole leaves (base, neck, wings and apex) of maguey plants with representative specimens of three stages of maturity with industrial importance. For carbohydrate characterization, high resolution liquid chromatography (HLPC) was used. The sugars found as fructose, glucose, sucrose, xylose and maltose coincide with those identified in other Agave species, significant differences are observed depending on the section and the state of maturity of the plant, the sugar concentration in the discarded sections of the plant (fructose: 5.79 – 4.80 mg mL-1) are considerable and statistically similar to those found in the stem (fructose: 2.49 mg mL-1) and the base of the leaf (fructose: 3.16 mg mL-1) (structure used in the mezcal production process). The results obtained can promote the integral use of the plant and diversification towards other industries such as pharmaceuticals, biofuels or foods.

A review on grafted, crosslinked and composites of biopolymer Xanthan gum for phasing out synthetic dyes and toxic metal ions from aqueous solutions

Biopolymer Xanthan gum (XG), an exo-polysaccharide obtained from the fermentation of simple sugars by bacteria Xanthomonas campestris under aerobic conditions exhibits interesting properties like biodegradability, high viscosity at a low shear rate and stability under a wide range of temperature and pH. These characteristics properties render it accessible to utilize as a stabilizer, suspending as well as an emulsifying agent in food industries, petroleum and oil refining industries, cosmetic industries, and as an adsorbent in wastewater treatment. However, XG hydrophilicity and water solubility characteristics not only restrict its application domain but also affect its thermal stability during processing. Therefore, the efforts are directed to improve its application spectrum by modifying the physical and chemical characteristics of biopolymer, taking advantage of the presence of different amenable functional moieties in XG. The chemical modifications of XG include the formation of cross-linked polymers, grafting of monomer to base polymers manipulating the functionality by removal/addition of chemical groups. Currently, the emphasis is on the development of XG based grafted/crosslinked bionanocomposites which can be tailored as a noble adsorbent for wastewater treatment for the remotion of toxic metals, coloured synthetic dyes and other industrial effluents from the aqueous medium. The emphasis of present review article is to address the structural, physical characteristics along with the focus on the development of chemically modified XG viz. grafted, crosslinked, nanocomposites, and functionally modified biopolymer. The potential applications of these modified XG polymers for phasing out synthetic dyes and transition metals ions from aqueous systems have been deliberated.

Construction of lactic acid overproducing Clostridium thermocellum through enhancement of lactate dehydrogenase expression

Rapid expansion of global market of lactic acid (LA) has prompted research towards cheaper and more eco-friendly strategies for its production. Nowadays, LA is produced mainly through fermentation of simple sugars or starchy biomass (e.g. corn) and its price is relatively high. Lignocellulose could be an advantageous alternative feedstock for LA production owing to its high abundance and low cost. However, the most effective natural producers of LA cannot directly ferment lignocellulose. So far, metabolic engineering aimed at developing microorganisms combining efficient LA production and cellulose hydrolysis has been generally based on introducing designer cellulase systems in natural LA producers. In the present study, the approach consisted in improving LA production in the natural cellulolytic bacterium Clostridium thermocellum DSM1313. The expression of the native lactate dehydrogenase was enhanced by functional replacement of its original promoter with stronger ones resulting in a 10-fold increase in specific activity, which resulted in a 2-fold increase of LA yield. It is known that eliminating allosteric regulation can also increase lactic acid production in C. thermocellum, however we were unable to insert strong promoters upstream of the de-regulated ldh gene. A strategy combining these regulations and inactivation of parasitic pathways appears essential for developing a homolactic C. thermocellum.

Stability Comparisons between Natural Archaeal and Engineered Archaeal‐Bacterial Heat‐Shock Protein Subunits (α, β, and β‐cohesin) and their Oligomeric Complexes

Hyperthermophilic archaea of the Order Sulfolobales express group II chaperonins, which are commonly referred to as “heat‐shock proteins” (HSPs) due to their upregulated expression upon heat shock. There are three HSP subtypes (HSPα, HSPβ, and HSPγ). Of these, HSPα and HSPβ (a.k.a., TF55 and TF56) subunits are the most thoroughly characterized and are known to stoichiometrically assemble into double‐nonameric (18‐mer) ring structures. These HSP complexes are known to play a significant role not only in the folding of nascent proteins but also in the protection of cytosolic proteins within cells under environmental stress such as high temperature flux. In this context, there has been significant interest in re‐engineering the system as an enzyme protection platform for industrial applications. The first such prototype platform was called a “rosettasome”. The rosettasome is an 18‐mer complex composed of subunits that were fusion proteins of the archaeal HSPβ and cohesion (Type I) from Clostridium thermocellum. Enzymes endowed with a dockerin (Type I) domain bind to cohesion and consequently sequester enzymes to the HSP complex. We previously demonstrated that use of cellulase‐charged rosettasomes on acid (or alkaline) pretreated wheat straw (and corn pericarp) results in an increase in lignocellulose deconstruction and polysaccharide reduction to simple fermentable sugars (e.g., glucose). However, the two‐fold enhancement observed was not sufficient to render the system economically viable. Recently, we re‐engineered the HSP system into a next‐generation mobile enzyme sequestration platform (mESP). In this study, the relative stability of HSP subunits (natural and engineered) and HSP complexes with different subunit compositions are assessed to determine the mESP configuration that exhibits the greatest thermo‐/acido‐tolerance. Transmission electron micrographs reveal the formation of both nonameric ring and nonameric double‐ring (18‐mer) structures. Using differential scanning calorimetry (DSC), the thermodynamic stability of individual subunits as well as homomeric and heteromeric HSP complexes were examined. Results from analytical ultracentrifugation (in conjunction with DSC, TEM, and gel electrophoresis data), reveal the composition and relative stability of HSP complexes. These data show that HSPα has the highest thermal stability of the three subunits tested. In addition, these data indicate that stability of HSP complexes is significantly dependent on the conditions used in complex assembly and subunit stoichiometry. These results and implications for mESP technology are discussed in detail.Support or Funding InformationU.S. National Science Foundation Molecular and Cellular Biosciences (MCB) grant (Award No. 1818346; PI‐Ceballos); U.S. National Science Foundation EArly‐concept Grants for Exploratory Research (EAGER) grant (Award No. 0929484; PI‐Ceballos)

Optimization of dilute sulfuric acid, aqueous ammonia, and steam explosion as the pretreatments steps for distillers’ dried grains with solubles as a potential fermentation feedstock

Distillers’ dried grains with solubles (DDGS) is the by-product of bioethanol production from starch-rich grains through dry-mill fermentation. In this study, dilute sulfuric acid hydrolysis, aqueous ammonia, and steam explosion as the pre-treatment methods were optimized. The central composite response surface methodology (RSM) design was used for optimization of dilute acid pretreatment, aqueous ammonia pretreatment. The steam explosion trials were evaluated. The results show that the dilute acid pretreatment at 121 °C is the most effective way of obtaining simple fermentable sugars (0.382 g/g DDGS). The levels of furfural and HMF was also 5.2 mg/g DDGS) and 1.6 mg/g DDGS, respectively, in the dilute sulfuric acid pretreated DDGS. On the other hand, maximum sugar yield for ammonia pretreatment was 0.129 g/g DDGS and 0.055 g/g DDGS for the steam pretreatment, while no significant amounts of furfural and HMF were observed for these two pretreatment methods.

Baker’s yeast: industrial applications and health benefits

Baker's yeast is used as a leavening agent in bread baking as it converts simple fermentable sugars in dough to CO2 and ethanol. Fermentation by yeast leads to the expansion of dough, its maturation and development of characteristic flavours in cereal-based products. Different strains of yeasts like Saccharomyces cerevisiae, S. exiguous, S. boulardii, etc. are widely used in nourishment and pharmaceutical industry. Yeast is a source of vitamin B, minerals, p-glucan fiber and protein and is used as health supplement. As probiotic, it plays a vital role in folate biofortification, detoxification and bioavailability of nutrients. Anti-cholesterolemic, anti-mutagenic, anti-oxidative and anti-tumuor potential of S. cerevisiae is currently under investigation. Yeast is exploited in several industrial processes including bioethanol production and bioremediation and is an excellent tool for biotechnological applications. This paper reviews the work done on baker's yeast and its industrial application and health benefits.

Production of cellulases by solid state fermentation using natural and pretreated sugarcane bagasse with different fungi

Abstract Lignocellulosic biomass is an important source of energy and it has been extensively studied in the production of second generation ethanol. For this purpose, the complex lignocellulosic matrix must be deconstructed by thermal or chemical pretreatment, followed by cellulose depolymerization using cellulolytic enzymes to release simple fermentable sugars. This process still has several techno-economical drawbacks, such as the cost of enzymes. Aiming to reduce the cost of theses enzymes, their production have been studied by solid-state fermentation (SSF) using low-cost agroindustrial residues as carbon source to the microbial growth. In this context, this work aimed at studying the operational conditions (temperature and moisture content) for the production of cellulases from the fungi Penicillium sp., Rhizomucor sp. and Trichoderma koningii INCQS 40331 (CFAM 422), utilizing natural sugarcane bagasse (NSB) and pretreated by acid-alkaline solution (AAB) and hydrogen peroxide (HPB) as substrates. The study was performed by using three-level factorial design (32) with central points. The results showed that the more suitable fungus for cellulases production was the Trichoderma koningii (8.2 IU/g substrate), followed by Penicillum sp (1.7 IU/g substrate). Moreover, the best results were obtained using NSB for all fungi. Statistical analyses showed that the temperature has a greater effect on the production of cellulases by the evaluated fungi.

Structural basis of product inhibition by arabinose and xylose of the thermostable GH43 β-1,4-xylosidase from Geobacillus thermoleovorans IT-08.

Complete degradation of the xylan backbone of hemicellulosic plant cell walls requires the synergistic action of endo-xylanases and β-1,4-xylosidases. While endo-xylanases produce xylooligosaccharides from xylan, β-1,4-xylosidases degrade the xylooligosaccharides into xylose monomers. The glycoside hydrolase family 43 β-1,4-xylosidase from Geobacillus thermoleovorans IT-08 is a promising, heat stable catalyst for the saccharification of hemicellulosic material into simple fermentable sugars, but it is competitively inhibited by its products arabinose and xylose. As a first step to help overcome this problem, we elucidated crystal structures of the enzyme in the unliganded form and with bound products, at 1.7–2.0 Å resolution. The structures are very similar to those of other enzymes belonging to glycoside hydrolase family 43. Unexpectedly, the monosaccharides are bound in very different ways. Arabinose preferentially binds in subsite -1, while xylose exclusively interacts with subsite +1. These structures and sugar binding preferences suggest ways for improving the catalytic performance of the enzyme by rational mutational design.

Catalytic conversion of ethanol into alkenes and acetaldehyde

Abstract Bioethanol is an example of a renewable energy source which can be produced not only by fermentation of simple sugars but also by depolymerisation of cellulose, as the second-generation feedstock, in the first step. This will help to further develop the bioethanol economy. Ethanol can be used as a promising platform molecule for the production of a variety of industrially important chemicals such as alkenes or oxygenates. Alkenes are produced industrially by petrochemical way mainly from crude oil, a non-renewable energy source. Conversion of ethanol to light olefins using an appropriate catalyst could replace the production of these key building blocks for the chemical industry. In this work, the focus is on the preparation and testing of heterogeneous catalysts in the transformation of ethanol to alkenes and acetaldehyde. In most cases, magnesia-based catalysts were used on a silica support during the experiment. Individual types of catalysts were compared in terms of yields of particular products, the effect of the feedstock load and that of calcination temperature of the catalyst on the catalytic activity are discussed. The highest ethylene yields (95 %) were achieved over an Mg-β-zeolite catalyst; the highest yield of 1,3-butadiene (29.1 %) was achieved in case of an Na/alumina catalyst; and the highest acetaldehyde yield (22.3 %) was achieved using a K-doped MgO/SiO2 catalyst.

Engineering Starch Kinases For Increased Biofuel Production Efficiency

The growth of the bioethanol industry over the last decade has been a result of the growing demand for gasoline fuels, which in the United States constitutes at least 10% by volume, and the implementation of higher Renewable Fuel Standards (RFS). Bioethanol is produced by the fermentation of simple sugars by yeasts and as a result starch feedstocks must undergo pretreatment steps. The various mechanical, thermal and chemical treatments used to degrade starch are both expensive and energy intensive. Alternatively, plants use a reversible phosphorylation mechanism to solubilize starch and access stored glucose for nocturnal metabolism. Starch is formed by linear α‐1,4 linked glucose units and branching glucose via α‐1,6 bonds which form insoluble helical structures. Starch kinases phosphorylate the crystalline layers, disrupting the helical structures, and exposing the polymer to hydrolysis by amylases. This mechanism could be adopted during biofuels production to decrease the need for solubilizing treatments. Starch kinases are characterized by two distinct domains: carbohydrate binding modules (CBMs) and a dikinase domain connected via a peptide linker. The CBM functions to locate the kinase on the starch substrate, which is subsequently phosphorylated by the kinase domain. In order to expand the substrate affinity of a kinase, we fused the CBM from a Neurospora crassa starch‐active polysaccharide monooxygenase to multiple dikinase domains. We defined the melting temperature of the chimeric proteins using differential scanning fluorimetry and found that the chimeric proteins had increased stability. Using [33P‐β‐]ATP, we radiolabeled starch with the chimeric proteins and found that they exhibited at least 7‐fold greater activity than wild type dikinase using maize, barley, and potato starch as the substrate.Support or Funding InformationNSF IIA‐1355438 (R. Andrews), NSF MCB‐1252345 (M. Gentry)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Characterization of novel Trichoderma hemicellulase and its use to enhance downstream processing of lignocellulosic biomass to simple fermentable sugars

Abstract Crude hemicellulase by novel mycoparasitic Trichoderma asperellum (GenBank accession nos. T. asperellum could withstand up to 50% selected hydrolytic and fermentation inhibitors. Supplement of hemicellulase crude to Celluclast 1.5 L at 1FPU:5U enhanced the hydrolysis of alkaline-treated OPEFB biomass achieving a 91.7% saccharification yield, higher than 77.9% yield or 12.2% yield when no hemicellulase was used or used without addition of cellulase respectively. The high saccharification yield, which has not been attained in any previous report on OPEFB, demonstrates the potential of T. asperellum for the development of efficient enzyme system for lignocellulosic bio-conversion. As far as we know, this is the first report on enhancement of lignocellulosic co-hydrolysis through synergism of hemicellulase crude by T. asperellum and commercial cellulase.

Phenolic compounds inhibit cellulase and xylanase activities of Cellulomonas flavigena PR-22 during saccharification of sugarcane bagasse

The enzymatic hydrolysis of sugar cane bagasse (SCB) releases simple fermentable sugars however, phenolic compounds (PCs) are also released from the lignin present in the structure of the lignocellulosic biomass limiting the production of sugars and therefore the fermentative process to convert these sugars to bioethanol. During the saccharification of SCB with holocellulases from Cellulomonas flavigena PR-22, 46μgmL−1 of PCs were produced, which inhibited 87 and 74% carboxymethyl cellulase (CMCase) and xylanases respectively resulting in a low concentration of reducing sugars (5.5gL−1) at the end of the process. Polymers such as polyethylene glycol 4000 (PEG) and polyvinylpyrrolidone (PVP) can prevent this inhibition due to their ability to chemically adsorb PCs. PEG and PVP were added to C. flavigena PR-22 enzyme extracts at 0.4% (w/v). PEG 4000 prevented CMCase inhibition, maintaining the original activity after the saccharification process, whereas xylanase production was increased by 47% when PVP was added.

The Effect of Microwave-NaOH Pretreatment and Hydrolysis Enzyme Using Trichoderma reesei-Aspergillus niger on Rice Straw Bioethanol Production

The process of bioethanol production from rice straw consists of two steps: (1) conversion of cellulose into simple sugars which is conducted by using microwave-NaOH pretreatment and straw hydrolysis using mold catalyst T.reesei and A. niger; and (2) fermentation of simple sugars into ethanol. In a microwave-NaOH pretreatment process has been obtained the best value content of cellulose in straw size of 100 mesh and a long exposure of 40 minutes for 72.70+1:10%. Crude cellulase enzyme activity of T.reesei isolation, A.niger and it mixtures were optimum at temperature of 50°C. The addition of crude enzyme from A.niger and T.reesei on a comparison of 1: 2 (v/v) was able to increase the yield of the rice straw cellulose hydrolysis which is produces sugar at 12.89 mg/ml (1.29% w/v) or 0.15% (w/v) when converted into ethanol. The glucose yield from rice straw was 25.47% with 3% ethanol.

Co-culture strategies for increased biohydrogen production

Biological hydrogen production from organic wastes is a less expensive, less energy-demanding, and environmental-friendly process. Pure monoculture delivers low H2 content and low yield; these limitations are overcome by a defined co-culture system, which outperforms mixed cultures with increased H2 yield. The strategies used in co-culture systems for increasing H2 production have been discussed in this review. The strategies include hydrolysis of a variety of complex substrates, such as cellulose, molasses, crude glycerol, and algal biomass into simple fermentable sugars for increased H2 yield by eliminating the use of exogenous enzymes. The strategies can bring geographically distant isolated microorganisms from different sources to coexist for simultaneous utilization of substrate and end metabolites into H2 production of 99.99% purity without the expenses of reducing agents. In the case of maximum hydrogen production using co-culture strategies, Clostridium, Enterobacter, and photo-fermenting bacteria in a consolidated bioprocess system will result in increased H2 yield. A co-culture system is more feasible to achieve theoretical H2 yield with high conversion efficiency of organic wastes, enhance the economic viability of H2 production, provide better effluent treatment quality, and concurrently address the limitations of H2 production. Copyright © 2015 John Wiley & Sons, Ltd.

Enzymatic Delignification of Biomass for Enhanced Fermentable Sugars Production

AbstractThe United Arab Emirates (UAE) has more than 40 million palm trees producing approximately 15 kg of waste fronds per tree. These fronds contain a large portion of polysaccharides, which can be hydrolyzed to simple fermentable sugars. Seaweed consists of macroalgae containing high portions of polysaccharides, which are also abundantly found on the coasts of UAE. The effectiveness of lignin to degrade enzymes for the pretreatment of biomass from palm trees fronds and indigenous seaweed (prior to enzymatic hydrolysis) has been investigated and compared to conventional chemical treatment. By treating with laccase, up to 9 and 24 % additional lignin was removed from palm fronds and seaweed, respectively. The performance of laccase was enhanced by using an ionic liquid, and a sugar yield of 12.6 % was achieved after treatment with laccase for only 1 hour. The proposed approach provides a promising simplification to the overall bioethanol production from biomass waste available globally in abundance, and in the UAE in particular.

An overview of key pretreatment processes employed for bioconversion of lignocellulosic biomass into biofuels and value added products.

The hunt for alternative sources of energy generation that are inexpensive, ecofriendly, renewable and can replace fossil fuels is on, owing to the increasing demands of energy. One approach in this direction is the conversion of plant residues into biofuels wherein lignocellulose, which forms the structural framework of plants consisting of cellulose, hemicellulose and lignin, is first broken down and hydrolyzed into simple fermentable sugars, which upon fermentation form biofuels such as ethanol. A major bottleneck is to disarray lignin which is present as a protective covering and makes cellulose and hemicellulose recalcitrant to enzymatic hydrolysis. A number of biomass deconstruction or pretreatment processes (physical, chemical and biological) have been used to break the structural framework of plants and depolymerize lignin. This review surveys and discusses some major pretreatment processes pertaining to the pretreatment of plant biomass, which are used for the production of biofuels and other value added products. The emphasis is given on processes that provide maximum amount of sugars, which are subsequently used for the production of biofuels.

Química e sustentabilidade: novas fronteiras em biocombustíveis

This contribution discusses the state of the art and the challenges in producing biofuels, as well as the need to develop chemical conversion processes of CO2 in Brazil. Biofuels are sustainable alternatives to fossil fuels for providing energy, whilst minimizing the effects of CO2 emissions into the atmosphere. Ethanol from fermentation of simple sugars and biodiesel produced from oils and fats are the first-generation of biofuels available in the country. However, they are preferentially produced from edible feedstocks (sugar cane and vegetable oils), which limits the expansion of national production. In addition, environmental issues, as well as political and societal pressures, have promoted the development of 2nd and 3rd generation biofuels. These biofuels are based on lignocellulosic biomass from agricultural waste and wood processing, and on algae, respectively. Cellulosic ethanol, from fermentation of cellulose-derived sugars, and hydrocarbons in the range of liquid fuels (gasoline, jet, and diesel fuels) produced through thermochemical conversion processes are considered biofuels of the new generation. Nevertheless, the available 2nd and 3rd generation biofuels, and those under development, have to be subsidized for inclusion in the consumer market. Therefore, one of the greatest challenges in the biofuels area is their competitive large-scale production in relation to fossil fuels. Owing to this, fossil fuels, based on petroleum, coal and natural gas, will be around for many years to come. Thus, it is necessary to utilize the inevitable CO2 released by the combustion processes in a rational and economical way. Chemical transformation processes of CO2 into methanol, hydrocarbons and organic carbonates are attractive and relatively easy to implement in the short-to-medium terms. However, the low reactivity of CO2 and the thermodynamic limitations in terms of conversion and yield of products remain challenges to be overcome in the development of sustainable CO2 conversion processes.

The Production and Characterization of Ethanol Fuel from Agricultural Products as an Alternative Fuel for Gasoline

The concern for efficient use of clean and alternative sources of energy other than fossil fuel has gathered rapid momentum all over the world. The most interesting development is the growing realization that ethanol is an alternative source to fuel and lubricants derived from the liquid fuel. This work, therefore, focuses on the experimental conducts in producing ethanol fuel from agricultural products (corn, guinea corn, and millet shaft) that are an easy source in Nigeria and to compare the performance of the fuel with gasoline based on the characteristics of the ethanol fuel produced. The agricultural products (corn, guinea corn, and millet shaft) were hydrolyzed using an alkaline treatment and acid hydrolysis; subsequent fermentation of simple sugars obtained from hydrolysis by yeast (Saccharomyces cerevisiae) produced bio ethanol and CO 2 . Results obtained revealed that the production of bio-ethanol was successfully carried out. One hundred grams each of the three samples gave yields of 65, 52, and 45 cm3 from corn, guinea corn, and millet shaft hydrolyzed, respectively. About 99.2% of anhydrous ethanol was achieved at the end of the drying process using charcoal (adsorbent), which is close to the theoretical value of 99.9% ethanol. The properties that the bio-ethanol have been tested for are relative density, flash point, sulphur content, vapor pressure, viscosity, latent heat of vaporization, and heat of combustion. The results obtained are relative density of 0.966, flash point is 55°C, and sulphur content of the ethanol fuel is 0.0251%, while the vapor pressure of the produced fuel is 25.7%. Other properties of the produced ethanol fuel are viscosity, which is 1.24 (cp) at 20°C, latent heat of vaporization is 635.3 kj/kg, while the latent heat of combustion of the produced ethanol fuel is 31300.23 kj/kg. These experimental values are relatively close to gasoline.