Due to its availability, low-price, and higher degree of reduction than lignocellulosic sugars, glycerol has become an attractive carbon source for the production of fuels and reduced chemicals. However, this high degree of reduction of carbon atoms in glycerol also results in significant challenges in regard to its utilization under fermentative conditions. Therefore, in order to unlock the full potential of microorganisms for the fermentative conversion of glycerol into fuels and chemicals, a detailed understanding of the anaerobic fermentation of glycerol is required. The work presented here highlights a comprehensive experimental investigation into fermentative glycerol metabolism in Escherichia coli, which has elucidated several key pathways and mechanisms. The activity of both the fermentative and respiratory glycerol dissimilation pathways was found to be important for maximum glycerol utilization, a consequence of the metabolic cycle and downstream effects created by the essential involvement of PEP-dependent dihydroxyacetone kinase (DHAK) in the fermentative glycerol dissimilation pathway. The decoupling of this cycle is of central importance during fermentative glycerol metabolism, and while multiple decoupling mechanisms were identified, their relative inefficiencies dictated not only their level of involvement, but also implicated the activity of other pathways/enzymes, including fumarate reductase and pyruvate kinase. The central role of the PEP-dependent DHAK, an enzyme whose transcription was found to be regulated by the cyclic adenosine monophosphate (cAMP) receptor protein (CRP)-cAMP complex, was also tied to the importance of multiple fructose 1,6-bisphosphotases (FBPases) encoded by fbp, glpX, and yggF. The activity of these FBPases, and as a result the levels of fructose 1,6-bisphosphate, a key regulatory compound, appear to also play a role in the involvement of several other enzymes during fermentative glycerol metabolism including PEP carboxykinase. Using this improved understanding of fermentative glycerol metabolism as a platform, E. coli has been engineered to produce high yields and titers of ethanol (19.8 g/L, 0.46 g/g), co-produced along with hydrogen, and 1,2-propanediol (5.6 g/L, 0.21 g/g) from glycerol, demonstrating its potential as a carbon source for the production of fuels and reduced chemicals.

<p>Glycerol is one of the by-products of transesterification of fatty acids for the production of bio-diesel. Value-added products such as hydrogen, wood stabilizers and liquid chemicals from catalytic treatment of glycerol can improve the economics of the bio-diesel production process. Catalytic conversion of glycerol can be used for production of value-added liquid chemicals. In this work, a systematic study has been conducted to evaluate the effects of operating conditions on glycerol conversion to liquid chemical products in the presence of acid catalysts. </p><p>Central composite design for response surface method was used to design the experimental plan. Experiments were performed in a fixed-bed reactor using HZSM-5, HY, silica-alumina and ã-alumina catalysts. The temperature, carrier gas flow rate and weight hourly space velocity (WHSV) were maintained in the range of 350-500 oC, 20-50 mL/min and 5.40-21.60 h -1, respectively. </p><p>The main liquid chemicals detected in liquid product were acetaldehyde, acrolein, formaldehyde and hydroxyacetone. Under all experimental conditions complete glycerol conversion was obtained over silica-alumina and ã-alumina. A maximum liquid product yield of approximately 83 g/100g feed was obtained with these two catalysts when the operating conditions were maintained at 380 oC, 26 mL/min and 8.68 h-1. Maximum glycerol conversions of 100 wt% and 78.8 wt% were obtained in the presence of HY and HZSM-5 at temperature, carrier gas flow rate and WHSV of 470 oC, 26 mL/min and 8.68 h-1. HY and HZSM-5 produced maximum liquid product of 80.9 and 59.0 g/100 g feed at temperature of 425 and 470 oC, respectively.</p><p>Silica-alumina produced the maximum acetaldehyde (~24.5 g/100 g feed) whereas ã-alumina produced the maximum acrolein (~25 g/100 g feed). Also, silica-alumina produced highest formaldehyde yield of 9g/100 g feed whereas HY produced highest acetol yield of 14.7 g/100 g feed. The effect of pore size of these catalysts was studied on optimum glycerol conversion and liquid product yield. Optimum conversion increased from 80 to 100 wt% and optimum liquid product increased from 59 to 83.3 g/100 g feed when the pore size of catalyst was increased from 0.54 in case of HZSM-5 to 0.74 nm in case of HY, after which the effect of pore size was minimal.

Glycerol kinase (GK) from Escherichia coli is allosterically controlled by fructose 1,6-bisphosphate (FBP) and the glucose-specific phosphocarrier protein IIAGlc of the phosphotransferase system. These controls allow glucose to regulate glycerol utilization. Fluorescence spectroscopic and enzyme kinetic methods are applied to investigate these allosteric controls in this study. The linkage between FBP binding and GK tetramer assembly is solved by observation of homo-fluorescence energy transfer of the fluorophore Oregon Green (OG) attached specifically to an engineered surface cysteine in GK. FBP binds to tetramer GK with an affinity 4000-fold higher than to dimeric GK. A region named the coupling locus that plays essential roles in the allosteric signal transmission from the IIAGlc binding site to the active site was identified in GK. The relationship between the coupling locus sequence in Escherichia coli or Haemophilus influenzae GK variants and the local flexibility of the IIAGlc binding site is established by fluorescence anisotropy determinations of the OG attached to the engineered surface cysteine in each variant. The local flexibility of the IIAGlc binding site is influenced by the coupling locus sequence, and in turn affects the binding affinity for IIAGlc. Furthermore, the local dynamics of each residue in the IIAGlc binding site of GK is studied systematically by the fluorescence anisotropy measurements of OG individually attached to each position of the IIAGlc binding site. The fluorescence steady-state anisotropy measurement provides a valid estimation of the local flexibility and correlates well with the crystallographic B-factors. Steady-state kinetics of FBP inhibition shows that the data are best described by a model in which the partial inhibition and FBP binding stoichiometry are taken into account. Kinetic viscosity effects show that the product-release step is not the purely rate-limiting step in the GK-catalyzed reaction. Viscosity effects on FBP inhibition are also discussed.

The easily utilized energy sources, glycerol, glucose and sucrose were used in broiler starter diets to improve growth performance. Trials investigated the effects of inclusion of easily utilized energy sources (EUES) on broiler duodenum and ileum histological developments. The effects of EUES on CHICKS delayed access to feed were investigated. In trial one, newly hatched chicks were randomly assigned to immediate (IA) or 36 hours delayed access to feed and water (DA) and fed 4 or 8% EUES during first 14 days post hatch. In trial two, males and female chicks were randomly assigned to IA or 48 hours DA, and fed 8% glycerol or glucose diets for a 14 days period. In both trials growth performance, duodenum and ileum developments were affected by dietary treatments. In conclusion, glycerol can be added into broiler starter diets up to 8%.

Due to an increased environmental awareness and thus, concerns over the use of fossil-based monomer for polymer production, there is an ongoing effort to find alternatives to non-renewable traditional monomers. This has ushered in the rapid growth in the development of bio-based materials such as green monomers and biodegradable polymers from vegetable and animal resources. Glycerol, as a renewable bio-based monomer, is an interesting candidate for sustainable polymer production. Glycerol is a renewable material that is a by-product of the transesterification of vegetable oils to biodiesel. Utilization of the excess glycerol derived from the growing biodiesel industry is important to oleochemical industries. The main objective of this thesis was to produce high molecular weight polyglycerol from glycerol and synthesize stimuli-responsive polyglycerol hydrogels. The work began with an investigation of the step-growth polymerization of glycerol to relatively high molecular weight polyglycerol using several catalysts. The catalytic reaction mechanisms were compared and the polymer products were fully analyzed. High molecular weight partially branched polyglycerol with multimodal molecular weight distributions was obtained. The polymerization of glycerol proceeded fastest with sulphuric acid as catalyst as indicated by the highest observed conversion of monomer along with the highest molecular weights. Theoretical models were used to predict the gel point and to calculate monomer functionality. High molecular weight polyglycerol was used to synthesize novel stimuli-responsive hydrogels. Real-time monitoring of step-growth polymerization of glycerol was investigated using in-line and off-line Attenuated Total Reflectance/Fourier Transform infrared (ATR-FTIR) technique.

The Onsager heat of transport, Q*, has been measured for water vapour above glycerol-water solutions (75 % to 94.5 % glycerol) over a temperature range of -46 to -32 ℃. For solutions of concentrations 80 % and above, Q* varied from 5.41 kJ mol-1 ± 0.97 to 17.37 kJ mol-1 ± 2.61, consistent with previous results for aniline and n-heptanol. The dissociation of glycerol-water complexes was not rate determining, as was the case for sulfuric acid-water solutions, and therefore the glycerol-water system is a better two component system analog for comparison with the CO2-water system than the sulfuric acid-water system.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 4 uppsatser.

Made available in DSpace on 2014-06-11T19:23:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-01-08Bitstream added on 2014-06-13T18:09:38Z : No. of bitstreams: 1 silva_riv_me_bauru_prot.pdf: 20922417 bytes, checksum: 7a0be809afb7e675e99bba1b3539c247 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O presente trabalho teve como objetivo preparar o compósito de 1% (massa) de rutênio suportado sobre o condutor misto cerâmico (iônico e eletrônico), 'Ti IND. x'('Gd IND. 0,2''Ce IND. 0,8')'IND. (1-x)''O IND. (2-δ)', onde 0'< OU ='x'<OU='0,1, para utilizar como catalisador de reforma e ânodo (eletrodo tipo reforma interna) em Células a Combustível de Óxido Sólido (SOFC). O suporte cerâmico foi sintetizado pelo Método do Precursor Polimérico e calcinado a 400ºC, 700ºC, 1000ºC e 1150ºC em atmosfera estática de ar, sendo caracterizado por análise térmica simultânea (TG/DTA), Difração de Raio X (DRX) com refinamento estrutural pelo Método de Rietveld (REMR), análise textural por adsorção de 'N IND. 2' a 77K, Microscopia Eletrônica de Varredura (MEV) e Energia Dispersiva de Raio X (EDX). O Ru foi depositado (1% em massa) sobre o suporte cerâmico pelo Método do Ácido Fórmico. Em seguida foi calcinado a 300ºC em atmosfera de 'N. IND. 2' e tratado a 1000ºC em atmosfera de 'H IND. 2' (20% em 'H IND. 2' ). A deposição do Ru foi confirmada pela Espectrometria de Emissão Atômica com plasma acoplado indutivamente (ICP-AES). A caracterização do compósito foi feita mediante DRX, MEV com Fonte de Emissão Eletrostática (MEV-FEG) e Microscopia Eletrônica de Transmissão (MET). por último, o material compósito de Ru foi submetido a testes catalíticos para hidro-reforma de glicerol. A análise térmica do suporte cerâmico mostrou que os compostos orgânicos são eliminados até 700ºC. Os resultados de DRX e REMR mostraram a presença fase única de fluorita (g.e. Fm3m) em T=700ºC para 0'< OU ='x'<OU='0,1 e em T=1000ºC, para x<0,1. Em T=1000ºC e em T=1150ºC observou-se a presença da segunda fase, de titanato de gadolínio ('Gd IND. 2''Ti IND. 2''O IND. 7', g.e. Fd3m) para x'>OU='0,1 e x'>OU='0,025, respectivamente... / The current work aimed to prepare the composite of ruthenium supported on the ceramic mixed conductor (ionic and electronic), 'Ti IND. x'('Gd IND. 0,2''Ce IND. 0,8')'IND. (1-x)''O IND. (2-δ)',where 0'< OU ='x'<OU='0,1, to be used as a catalyst for the reforming and anode (internal reforming electrode) in Oxide Solid Fuel Cells (SOFC). The ceramic supports were synthesized by Polymeric Precursor Method and calcined at 400ºC, 700ºC, 1000ºC and 1150ºC in air. The characterization was carried out by simultaneous thermal analysis (TG/DTA), X-ray Diffraction (XRD) being the structure refined by Rietveld Method (SRRM), textural analysis by adsorption of 'N IND. 2' at 77K, Scanning Electronic Microscopy (SEM) and Energy Dispersive X-ray (EDX). The Ru was deposited on ceramic support by Formic Acid Method, calcined at 300ºC in 'N. IND. 2' and calcined at 1000ºC under 20vol% 'H IND. 2' flow. The deposition was confirmed by Inductively Coupled Plasma - Atomic Emission Spectrometry (ICP-AES). The characterization of the composite was performed by XRD, Field Emission Gun - Scanning Electronic Microscopy (FEG-SEM) and Transmission Electronic Microscopy (TEM). Finally, the catalytical activity of the composite material for glycerol steam reforming reaction was evaluated. The thermal analysis showed that most of organic compounds derived from the synthesis is eliminated up to 700ºC. The XRD and SRRM results showed that the samples crystallized as fluorite single phase (s.g.Fm3m) at T=700ºC for 0'< OU ='x'<OU='0,1and T=1000ºC,for x<0,1. The secondary phase of ('Gd IND. 2''Ti IND. 2''O IND. 7', g.e. Fd3m) was observed in the sample with x'>OU='0,1 when calcined at T=1000ºC and x'>OU='0.025 for the calcination temperature of 1150ºC. The textural analysis showed that the samples treated at 700ºC are mesoporous solids and, significant surface and porosity loss took place when treated at 1000ºC... (Complete abstract click electronic access below)

O glicerol é o principal produto obtido da síntese do biodiesel a partir de óleos vegetais e gordura animal, sendo gerado em 10 % da produção do biodiesel. Glicerol é um subproduto de muitos processos industriais tornando-se um substrato potencialmente atrativo para a produção de produtos de valor agregado através de ação bacteriana. Devido a sua alta produção, e sendo, consequentemente, um problema futuro caso este não seja consumido, uma alternativa para utilização do glicerol é a sua conversão em produtos de alta utilidade, tais como o hidrogênio, etanol, 1,3-propanodiol etc. A transformação do glicerol por processos biotecnológicos pode ser socialmente atrativa visto que existe grande interesse em buscas de alternativas para a utilização deste produto evitando seu acúmulo no meio ambiente. O presente trabalho teve como objetivo selecionar bactérias capazes de degradar glicerol residual da síntese química de biodiesel, e ter como subprodutos a formação de H2 e etanol, produtos de alto interesse social. Vários microrganismos foram testados quanto à ação de degradação do glicerol. Inicialmente, realizaram-se testes com consórcio microbiano ambiental (lodo), com isolamento e identificação das bactérias nele presentes. A partir desta etapa foi selecionada, através de fermentações anaeróbias, a cepa (bactéria) de maior potencial na degradação do glicerol e conversão em bioprodutos tais como, hidrogênio e etanol, sendo a bactéria Klebsiella pneumoniae BLb01 a que apresentou 100 % de degradação do glicerol residual com a melhor capacidade de produção de H2 e etanol. Após a seleção da cepa, realizaram-se testes de otimização das condições de cultivo para a produção de hidrogênio, utilizando planejamento experimental do tipo Plackett- Burman, Fatorial Fracionário e Delineamento Composto Central Rotacional. Os resultados obtidos mostraram que a maior produção de hidrogênio (45 % mol) foi obtida com o meio de cultivo constituído da seguinte composição: (30 g.L-1glicerol, pH 9, T de 39 °C, 3 g.L-1de extrato de levedura, 3 g.L-1 de K2HPO4 g.L-1 e 1,0 g.L-1 KH2PO4). Paralelamente foram realizados estudos utilizando este mesmo consórcio microbiano ambiental com diferentes pré-tratamentos (dessecação, térmico, básico, ácido e congelamento). O tratamento de dessecação apresentou o melhor desempenho na degradação do glicerol (66 %) e produção de H2 (34 %mol). / Glycerol is the main product resulting from the biodiesel synthesis from vegetable oils and animal fat, being equal to 10% of the biodiesel production. Glycerol is a byproduct of many industrial processes becoming a potentially attractive substrate for obtaining higher aggregate value products through bacterial action. Due to its high production and being, as a consequence, a future problem if not consumed, an alternative use for glycerol is its conversion in more useful products as hydrogen, ethanol, 1-3-propanediol etc. The transformation of glycerol by biotechnological processes can be socially attractive since there is a great interest in seeking alternatives for using this product avoiding its accumulation in the environment. The present work aims to select bacteria able to degrade residual glycerol from biodiesel synthesis forming hydrogen and ethanol, products of high social interest, as byproducts. Several microorganisms were tested as far as glycerol degrading is concerned. Initially, tests with environmental microbial consortium (sludge) were carried out isolating and identifying the bacteria present in it. Afterwards, through anaerobic fermentations, the strain with the greatest glycerol degradation potential and conversion in byproducts as hydrogen and ethanol was selected. The bacterium Klebsiella pneumoniae BLb01 presented 100% glycerol degradation with the best capacity of hydrogen and ethanol production. After the strain selection, tests of growing conditions optimization for hydrogen production were carried out using experimental planning type Placket-Burman, Fractional Factorial and Central Rotational Compound Delineation. The results showed that the highest hydrogen production (45 mol%) was achieved with the growing medium consisting of: glycerol 30 g.L–1, pH = 9, T = 39°C, yeast extract 3 g.L–1, K2HPO4 3 g.L–1. In parallel studies using the same environmental microbial consortium with different pre treatments (drying, thermal, basic, acid and freezing) were carried out. The drying treatment presented the best result for glycerol degrading (66% and hydrogen production (34 mol%).