Made available in DSpace on 2017-07-10T15:14:39Z (GMT). No. of bitstreams: 1 Daiana.pdf: 1204042 bytes, checksum: e2be546556cf75e2766127d88f17ae3e (MD5) Previous issue date: 2016-03-02 / Cassava (Manihot esculenta Crantz) in addition to being easy to cultivate a plant is considered the highest productivity calories and higher biological efficiency as a source of energy, presenting a high starch content. Some by-products are generated from the processing of cassava among them the brown bark, bark, disposal, the crueira, fiber, bran and bagasse or scanning. The cassava meal is characterized as a starchy source that can be converted into sugars for obtaining biofuel, this work aimed to produce ethanol from cassava processing this waste. This study was conducted in Cascavel / PR, were obtained waste in four different potato starch manufacturers, namely: starch manufacturer Home, starch manufacturer Starches New World, the starch manufacturer Novo Horizonte and MCR starches, there was analysis of chemical parameters of samples, starch content, sugar, pH, raw grease, moisture and ashes. For the process of obtaining the ethanol the samples were subjected to enzymatic hydrolysis using alpha-amylase and amyloglucosidases, they were then fermented and distilled. The samples were analyzed by mass spectrometry to verify the presence of ethanol. The samples showed high starch content about 60% on average, all acid had been adjusted with NaOH to the hydrolysis process. The solutions of one treatment, presented a de12,6% ethanol content, two treatment 48.5% and 53.3% treatment four Solving the three treatment presented a very different baseline standard solution being that his analysis becomes difficult, but by the spectral comparison between the solution treatment and the treatment with three one expected to be with concentrations close to each other, yielding a value of approximately 12% for three treatment. The cassava meal is a potential biomass for ethanol production, with a significant content of starch, and responding to efficiently process using hydrolysis and saccharification enzymes / A mandioca (Manihot esculenta Crantz) além de ser uma planta de fácil cultivo é considerada com uma alta produtividade de calorias e a de maior eficiência biológica como fonte de energia, apresentando um alto teor de amido. Alguns subprodutos são gerados a partir do processamento da mandioca dentre eles, a casca marrom, a entrecasca, o descarte, a crueira, a fibra, o bagaço ou farelo e a varredura. O farelo de mandioca é caracterizado como uma fonte amilácea que pode ser convertida em açúcares para a obtenção de biocombustível, com este trabalho objetivou-se produzir etanol a partir deste resíduo de processamento da mandioca. O presente estudo foi realizado em Cascavel/PR, foram obtidos resíduos em quatro diferentes fecularias, sendo elas: fecularia Lar, fecularia Amidos Mundo Novo, fecularia Novo Horizonte e MCR amidos, realizou-se análise dos parâmetros químicos das amostras, teor de amido, açucares, pH, matéria graxa, umidade e cinzas. Para o processo de obtenção de etanol as amostras foram submetidas à hidrólise enzimática, utilizando alfa-amilase e amiloglucosidases, posteriormente foram fermentadas e destiladas. As amostras foram submetidas à análise em espectrofotometria de infravermelho para constatar a presença de etanol. As amostras apresentaram alto teor médio de amido de 60%, todas as amostras apresentaram acidez sendo corrigidas com NAOH para o processo de hidrólise. As amostras foram destiladas com concentração de 10%. A solução da amostra um, apresentou um teor de etanol de 12,6%, amostra dois 48,5% e amostra quatro de 53,3% A solução da amostra três apresentou uma linha base muito diferente da solução padrão sendo que sua análise tornou-se difícil, mas pela comparação espectral entre a solução da amostra três e da amostra um considerou-se que as concentrações entre as mesmas estavam próximas entre si, obtendo-se um valor estimado em 12% para a amostra três. O farelo de mandioca é uma biomassa em potencial para a produção de etanol, apresentando teor significante de amido, e respondendo de forma eficiente ao processo de hidrólise e sacarificação utilizando enzimas

One of the challenges in the 21st Century is to overcome the recalcitrance of lignocellulose for the production of liquid biofuels. Lignin is one of the key factors in this recalcitrance. Grasses such as Miscanthus and switchgrass could become major sources of lignocellulose. Barley has potential as a genetically-tractable research model for such novel bioenergy crops and also as a bioenergy crop itself. This thesis concerns the 4CL and the CCR enzymes on the lignin pathway which were chosen as the targets to manipulate lignin in barley. They were selected because there is evidence that suppression of each of them in dicot species can lead to increased saccharification. The 4CL and CCR genes constitute multigene families where members have different expression patterns. RNAi was used to down-regulate 4CL1 and CCR1 using a constitutive promoter via Agrobacterium-mediated transformation of barley. From an extensive screen of the primary transformants for changes in protein level and lignin content, six CCR and four 4CL lines were taken forward for detailed analysis. Antibodies were also raised against barley 4CL and CCR recombinant proteins and these showed substantial reductions in the respective target protein levels in the RNAi lines. Both 4CL and CCR transgenic lines had significant reductions in lignin content, and CCR lines had changes in lignin structure due to changes in the proportions of acid soluble and acid insoluble lignin. No substantial consistent adverse effects on key agronomic traits were apparent in the 4CL and CCR transgenics. Selected 4CL and CCR transgenics had improved saccharification yield after using three different pretreatment methods, which is a desirable feature for biofuel production.

As biocélulas a combustível enzimáticas (BFCs) são dispositivos eletroquímicos que convertem energia química em energia elétrica, utilizando enzimas como biocatalisadores. Quando miniaturizada, uma BFC pode ser implantada em animais vertebrados e invertebrados, vislumbrando-se sua utilização na produção de energia elétrica para alimentar microdispositivos biomédicos e microssensores em pequenos insetos. No entanto, ainda é um desafio obter BFCs implantáveis e miniaturizadas, com uma potência suficiente (dezenas de microwatts) para alimentar microcircuitos eletrônicos de maneira estável e em longo prazo. Diante do exposto, esta tese de doutorado apresenta um estudo das propriedades eletroquímicas de eletrodos enzimáticos, visando a aplicação em BFCs de glicose/O2 miniaturizadas e implantáveis. Para isso, utilizaram-se fibras flexíveis de carbono (FCFs) modificadas com as enzimas bilirrubina oxidase (BOx) no cátodo e glicose desidrogenase (GDh) NAD-dependente no ânodo, a fim de se obter a redução de O2 e a oxidação de glicose, respectivamente. Os resultados obtidos mostram que FCFs previamente submetidas a um tratamento químico de oxidação com permanganato de potássio e com posterior eletrodepolimerização do mediador vermelho neutro produzem bioânodos estáveis e robustos. Estes eletrodos, combinados com biocátodos compostos por FCFs na ausência de mediadores redox, foram utilizados em BFCs miniaturizadas, que foram implantadas em formigas da espécie Atta sexdens rubrupilosa. A potência máxima da BFC operando in vivo foi 13,5 ± 3,8 µW cm-2 em 190 ± 58,9 mV, com corrente máxima de 143 ± 40,2 µA cm-2 e a voltagem de circuito aberto de 260 ± 99,6 mV. Acredita-se que estes valores ainda possam ser otimizados e este trabalho contribui para mostrar que a flexibilidade das FFC, a presença de um mediador de elétrons polimérico no ânodo, o uso do tratamento químico de oxidação com permanganato de potássio das fibras e a miniaturização dos eletrodos são elementos importantes, e que podem ser considerados no desenvolvimento de biocélulas a combustível implantáveis. / Enzymatic biofuel cells (BFCs) are electrochemical devices that convert chemical energy into electrical energy using enzymes as biocatalysts. When miniaturized, BFCs can be implanted in vertebrate and invertebrate animals and, their use to produce electrical energy to feed biomedical microdevices and micro-sensors in small insects can be observed. However, it is still challenging to obtain implantable and miniaturized BFCs, with sufficient power (tens of microwatts) to power electronic microcircuits in a stable and long-term manner. In view of the above, this PhD thesis presents a study of the electrochemical properties of enzymatic electrodes, aiming to use them in miniaturized and implantable glucose/O2 BFCs. In order to obtain a reduction in O2 and oxidation of glucose, flexible carbon fibers (FCFs) modified with bilirubin oxidase (BOx) enzymes in the cathode and glucose dehydrogenase (GDh) at the anode, respectively, were used. The results show that FCFs previously submitted to a chemical treatment of oxidation with potassium permanganate and, subsequently, electropolymerization of the neutral red mediator produce stable and robust bioanodes. These electrodes, combined with biocathodes consisting of FCFs in the absence of redox mediators, were used in miniaturized BFCs, which were implanted in Atta sexdens rubrupilosa ant species. The BFC maximum power source, operating in vivo, was 13.5 ± 3.8 μW cm-2 at 190 ± 58.9 mV, with a maximum current of 143 ± 40.2 μA cm-2 and the open circuit voltage was 260 ± 99.6 mV. Although these values can be optimized, this research shows that the flexibility of the FCF, the presence of a polymer electron mediator on the anode, using the chemical treatment of oxidation with potassium permanganate of the fibers and electrode miniaturization are important elements, which can be considered in the development of implantable biofuels.

O Brasil vem se destacando como pioneiro no desenvolvimento de um setor ainda incipiente no âmbito mundial. Um setor que apresenta tecnologia nacional e atende a uma busca para soluções ecológicas frente a uma exigência social cada vez mais estreita para a redução de poluentes. Este setor é conhecido como biocombustíveis que podemos englobar a produção de álcool, biodiesel, biogás, e carvão vegetal. O trabalho propõe estudar uma parte do setor de agroenergia conhecido como o setor de biocombustíveis, delimitado pelos segmentos: biodiesel, álcool, carvão vegetal para uso siderúrgico e biogás, apresentando suas vantagens econômicas, sociais e ecológicas. Propõe criar um modelo econômico de avaliação de empresas deste setor, buscando na literatura os modelos de avaliação existentes, discutindo a aplicação de cada um deles de forma a satisfazer os diversos níveis de demanda pelas diferentes necessidades dos leitores. Além disso, apresenta as dificuldades na busca de dados que poderão ser utilizados em outros setores com o mesmo grau de maturidade. Por ser um trabalho de avaliação de empresas, existe a necessidade de um aprofundamento das premissas e estudo dos parâmetros a serem considerados, desta forma, surge a necessidade de um estudo do setor amplo. Desta forma, por falta de dados deu-se atenção apenas nos segmentos de etanol e biodiesel. Para os diferentes segmentos deste setor, foi necessário utilizar diferentes fontes de informação: para o segmento de biodiesel, pesquisou empresas de porte padrão de mercado e adotou um fluxo de caixa para determinar este valor, utilizando diferentes insumos (algodão, soja, girassol e mamona) nas diferentes regiões do Brasil. No segmento de álcool, foi utilizada uma empresa já existente buscando aproximar de um modelo para o cálculo de empresas em diferentes proporções álcool/açúcar e estruturas de capital. / Brazil still comes if detaching as pioneering in the development of a sector incipient in the world-wide scope. A sector that presents national technology and takes care of to a search for ecological solutions front to a social requirement each narrower time for the reduction of pollutants. This sector is known as that we can mention the alcohol production, biodiesel, biogas and vegetal coal agroenergy. The work considers studying a part of the known sector of agroenergy as the sector of biofuels, delimited for the segments alcohol, biodiesel and vegetal coal, presenting its economic, social and ecological advantages. It considers creating a economic model of evaluation of companies of this sector, searching in literature the existing models of evaluation, arguing the application of each one of them of form to satisfy the diverse levels of demand for the different necessities of the readers. Moreover, it presents the difficulties of search of data that could also be used in other sectors in the same maturity degree. For the different segments of this sector, it was necessary to use different sources of information: for the segment of biodiesel, it searched transport companies market standard and adopted a box flow to determine this value, using different products (cotton, soy, sunflower and mamona) in the different regions of Brazil. In the alcohol segment, an existing company was used already searching to approach to a model for it calculates of companies in different ratios alcohol/sugar and structure of capital.

Esta dissertação apresenta uma análise comparativa dos aspectos sociais e econômicos decorrentes da produção dos biocombustíveis, etanol e biodiesel, nos principais países produtores e consumidores da atualidade Brasil, Estados Unidos e Alemanha. Para tal, os biocombustíveis foram analisados por intermédio dos dados das matrizes energéticas, da produção de matéria-prima e do biocombustível, do consumo interno, das políticas de suporte, barreiras tarifárias e não tarifárias, bem como dos gargalos existentes. Nos aspectos econômicos foram abordados indicadores da macroeconomia, indicadores específicos para biocombustíveis, a logística e a presença de subsídios. Nos aspectos sociais, a situação do trabalhador rural foi analisada enfatizando o trabalhador temporário imigrante na agricultura. O histórico das políticas possibilitou verificar a associação entre os estímulos políticos e a variação na produção. A construção dos cenários permitiu estimar a área necessária para expansão da produção de biocombustíveis. Neste grupo heterogêneo de países, em que as características sociais e econômicas são distintas, verificou-se que a legislação apresenta peculiaridades conforme a realidade de cada país. Com relação aos aspectos sociais, a situação dos trabalhadores temporários imigrantes na agricultura é semelhante, apresentando como características em comum a faixa etária, o grau de escolaridade e a remuneração. No que diz respeito aos biocombustíveis, etanol brasileiro é competitivo com o combustível fóssil correspondente, sem ajuda de subsídios. Apenas recentemente, o biodiesel apresentou aumento significativo na produção, após políticas de incentivo nos três países estudados. A produção e o consumo de biocombustíveis têm avançado nos três países. Entretanto, o Brasil apresenta a maior aptidão para produção de etanol, da atualidade, devido à possibilidade de expansão agrícola e ao tipo de matéria-prima utilizada que possui um balanço energético melhor. Nos Estados Unidos e na Alemanha, o custo de produção e a menor disponibilidade de terras agriculturáveis são vetores desfavoráveis à produção de biocombustíveis. / This study aims at a comparative analysis of the social and economic aspects, as a result of biofuels production, ethanol and biodiesel, in the three main producing and consuming countries The United States, Germany, and Brazil. To that end, there were analyses of biofuels production in several data fields such as; energy matrix, feedstock and biofuels production, local consumption, supportive policies, tariff and non-tariff barriers and existing bottlenecks. In the economic aspects, it was analyzed some macroeconomic indicators, biofuels indicators, logistics and subsidies. In respect of social aspects, the situation of the rural worker was analyzed, emphasizing the rural temporary foreign worker. The historical review of biofuels policies enabled to verify the association between the biofuels policies support and the biofuels production variation. It was possible to estimate the amount of land required for the expansion of biofuels production by the construction of scenarios. In this heterogenic group of countries with distinct social and economic characteristics, it was observed that the legislation development process follows each countrys reality. Despite of social aspects, the condition of the rural temporary foreign worker is alike, presenting common characteristics such as; age average, educational level and wage. Regarding the biofuels involved in this study, the Brazilian ethanol is more competitive with the regular fossil fuel even without subsidies. Only recently, there was a significant increase in the biodiesel production, after support policies in the three countries. Lately, the production and consumption of biofuels have been increasing in the three countries. Nevertheless, currently, Brazil has the major possibility to enhance biofuels production due its land availability and the use of a feedstock with the highest energy balance. In The United States and Germany the production costs and the lower quantity of agricultural land availability are disadvantages to their biofuels production.

The greatest political, scientific, and engineering challenge of the 21st century is finding a viable solution to limit anthropogenic greenhouse gas emissions (CO2) to curb the effects of global climate change. All sectors of society need to contribute to alleviate this problem, but industrial operations must play a significant leadership role. Some of these industries include: metallurgy, cement, power, agriculture and forestry. In particular, the iron/steel, cement, and power generation industries use coal on account of its high energy density among solid fuels. Coal combustion yields 720 tonne CO2/GWh, and produces fine particulates, sulphur and nitrous oxides, along with excess CO2 contributing to climate change. In comparison, biomass (such as agricultural and forestry residues) has a solid fuel rating of 25-100 tonne CO2/GWh; therefore, biomass fuels are considered more sustainable since the living biomass consumed CO2 in the early part of its life cycle. However, biomass has significant industrial shortcomings for its use as fuel at large scale, including low energy content, density, and hydrophobicity relative to coal. In short, biomass fuels cannot be substituted without major infrastructure changes which add economic penalties that industry is currently unwilling to absorb. Biomass upgrading routes were considered in this thesis. These include densification, torrefaction, and integrated torrefaction and densification (ITD). The first half of the methodology involved converting woody biomass (willow residue and poplar bark), agricultural residue (switchgrass plants), and pulp mill waste via a single pellet/briquette press at different densification temperatures and pressures. The second half of the methodology involved product characterization of each batch of pellets and briquettes. In this work, pellets and briquettes were tested for physical characteristics (density and durability), chemical differences (energy content and hydrophobicity), and transport phenomena characteristics (drying profiles). First, results showed that extrusion of torrefied biomass at 300°C with an estimated pressure of 10 MPa creates partially formed pellets from agricultural residues. Using the concept of ITD (temperature range 220-325°C and pressure range 40 and 215 MPa), the density was found to be 1000-1250 kg/m3 for pellets and briquettes. The degree of compression from the loose biomass was on the order of 3-10 which corresponds with theoretical expectations. Material density increased with increasing pressure. The solid yield of pellets and briquettes decreased with increasing temperature, and results aligned with micro-scale thermogravimetric analysis. The larger ITD briquettes (produced at T = 325°C, P = 40 MPa) were evaluated for calorific value and found to fall in the lignite classification (O/C < 0.4 and H/C < 1.2) on a van Krevelen diagram. The resulting ITD pellets and briquettes were found to have a durability similar to commercial materials (durability > 97%), and to be more hydrophobic (8 wt% moisture absorption compared to 35 wt%). The drying time of ITD materials was faster than commercial torrefied briquettes, with an effective diffusivity of 1.5×10-6 m2/s compared to 7.3×10-9 m2/s likely because of a smaller pore volume in ITD briquettes. Further pilot scale studies would help improve the ITD methodology and make the process more appealing for the replacement of coal fuels.

Uncertainty in the global energy market and negative environmental impacts associated with fossil fuels has led to renewed interest in alternative fuels. The scalability of new technologies and production pathways are critically being evaluated through economic feasibility studies and environmental impact assessments. This work investigated the conversion of agricultural wast, delactosed whey permeate (delac), with yeast fermentation for the generation of biofuel via hydrothermal liquefaction (HTL). The feasibility of the process was demonstrated at laboratory scale with data leveraged to validate systems models used to perform industrial-scale economic and environmental impact analyses. Results showed a minimum fuel selling point of $4.56 per gasoline gallon equivalent (CGE), a net energy ratio (NER), defined as energy required to process biofuel divided by energy in the biofuel produced, of 0.81 and greenhouse gas (GHG) emissions of 30.03 g CO2-eq MJ-1. High Production costs can be attributed to operational temperatures of HTL while the high lipid yields of the yeast counter these heating demands, resulting in a favorable NER. The operating conditions of both fermentation and HTL contributed to the majority of GHG emissions. Further discussion focuses on optimization of the process, on the metrics of TEA and LCA and the evaluation of the process, on the metrics of TEA and LCA, and the evaluation of the process through a sensitivity analysis that highlights areas for directed research to improve commercial feasibility.

Efforts are being made to replace petroleum-derived fuels with biofuels in a cost competitive manner. It is apparent that the continued use of petroleum is futile as population and technological growth put increasing pressure on the demand for cheap energy and chemicals. Diminishing resources, civil unrest in the Middle East, and the impact of using petrochemicals on the environment are critical driving forces for research in generating renewable petroleum replacements that can be produced with a limited carbon-footprint. Today, biofuels are derived mostly from land-based plants, but their potential for displacing petroleum is limited due to the competition with available farmland used in food production as well as their relatively slow growth rates. Microorganisms as single-cell factories for the production of biofuels have a promising outlook since they do not compete with the food and feed supply and they lack the necessity of arable land used in cultivation. Viable biofuel production hinges upon obtaining sufficient biofuel yields, lowering the costs of processing, production of value-added products, and real-life evaluation of the produced fuels. Herein, the current understanding of microbial biochemistry as well as new findings in the role of ATP citrate lyase in lipid accumulation in oleaginous yeasts will be discussed. Also, description of a novel two-step process that generates biodiesel blends from oleaginous microbes will be given. To facilitate the viability of microbial biofuel production, concomitant production of heterologous lactoferrin using Kluyveromyces lactis will be described. Lastly, the real-life evaluation of these microbial biofuels in a diesel engine is reported. The focus of this dissertation will be directed towards addressing the issues related to microbial biofuel production in order to facilitate the viability of biofuel production such that petroleum use can be displaced by more renewable and clean methodologies.

The Federal Reserve has increased nominal interest rates since early 2016. It is expected that commodity prices will drop in response to this monetary intervention. The overshooting hypothesis explains that commodity prices are more flexible than manufacturing prices and therefore are more volatile. In this situation, it is expected that agricultural commodities decline significantly (i.e., overshoot) and gradually return to their long-run equilibrium. This adjustment behavior has implications for income stability and financial viability of farmers. This research contributes to the overshooting literature by including the energy sector in the overshooting model. The interlinks between energy and other sectors in the economy as well as the vast resource allocation to biofuel production in recent decades demand more attention to the impact of energy on the dynamic adjustment path of relative prices’ reaction to monetary shocks. We assume energy prices have independent adjustment path and include the links between the energy and agricultural sectors through biofuel production in our model. Our theoretical model shows that by including energy prices in the model, agricultural prices and the exchange rate overshoot less than the prediction of prior studies. This happens because we expect that flexible energy prices share the burden of the shock with other flexible prices in the model. We also describe how an increasing share of biofuels in the total fuel consumption will reduce the flexibility of energy prices. In our empirical analysis, we use monthly data from January 1975 to December 2017 for three producer price indexes (i.e., agricultural commodities, energy, and industrial goods), exchange rates, and money supply to test the overshooting hypothesis. We found the series to be nonstationary and cointegrated of the order one, I(1). Thus, we estimated a vector error correction model to identify the short run adjustment parameters while maintaining the long-run relationships between the variables. We identify and control for three possible structural breaks in the data that coincide with two economic crises and the biofuel production era. We also estimated the empirical model using a sub-sample from January 1975 to March 1999 and compared the results with the findings in previous studies. Our empirical results confirm the theoretical expectation that agricultural commodities adjust faster than manufacturing prices. The analysis of the impulse response functions shows that after a money supply shock, agricultural prices were the most responsive, followed by energy prices and exchange rates. In both full sample and the sub-sample, the volatility of prices and exchange rates happen during the first 5 to 10 months. The sluggish adjustment of manufacturing prices was evident from the corresponding impulse response functions. The empirical evidence rejects the long-run money neutrality, consistent with the findings of previous empirical studies. Compared to previous models, our empirical model shows that including energy prices will reduce the extent to which agricultural commodities overshoot. Therefore we expect the disturbances to the farm income variability, in response to monetary policy, to be less than what prior model would have estimated. In this regard, energy prices are a stabilizing factor in this model. We find that increased share of biofuel from total fuel consumption would positively affect the overshooting of agricultural prices. So, higher biofuel mandates could reduce the flexibility of the energy prices and therefore have an adverse effect on the farm price stability.

Microorganisms are capable of producing advanced biofuels that can be used as ‘drop-in’ alternatives to conventional liquid fuels. However, vital physiological processes and membrane properties are often disrupted by the presence of biofuel and limit the production yields. In order to make microbial biofuels a competitive fuel source, finding mechanisms for improving resistance to the toxic effects of biofuel production is vital. This investigation aims to identify resistance mechanisms from microorganisms that have evolved to withstand hydrocarbon-rich environments, such as those that thrive near natural oil seeps and in oil-polluted waters. First, using genomic DNA from Marinobacter aquaeolei, we constructed a transgenic library that we expressed in Escherichia coli. We exposed cells to inhibitory levels of pinene, a monoterpene that can serve as a jet fuel precursor with chemical properties similar to existing tactical fuels. Using a sequential strategy of a fosmid library followed by a plasmid library, we were able to isolate a region of DNA from the M. aquaeolei genome that conferred pinene tolerance when expressed in E. coli. We determined that a single gene, yceI, was responsible for the tolerance improvements. Overexpression of this gene placed no additional burden on the host. We also tested tolerance to other monoterpenes and showed that yceI selectively improves tolerance. Additionally, we used genomic DNA from Pseudomonas putida KT2440, which has innate solvent-tolerance properties, to create transgenic libraries in an E. coli host. We exposed cells containing the library to pinene, selecting for genes that improved tolerance. Importantly, we found that expressing the sigma factor RpoD from P. putida greatly expanded the diversity of tolerance genes recovered. With low expression of rpoDP. putida, we isolated a single pinene tolerance gene; with increased expression of the sigma factor our selection experiments returned multiple distinct tolerance mechanisms, including some that have been previously documented and also new mechanisms. Interestingly, high levels of rpoDP. putida induction resulted in decreased diversity. We found that the tolerance levels provided by some genes are highly sensitive to the level of induction of rpoDP. putida, while others provide tolerance across a wide range of rpoDP. putida levels. This method for unlocking diversity in tolerance screening using heterologous sigma factor expression was applicable to both plasmid and fosmid-based transgenic libraries. These results suggest that by controlling the expression of appropriate heterologous sigma factors, we can greatly increase the searchable genomic space within transgenic libraries. This dissertation describes a method of effectively screening genomic DNA from multiple organisms for genes to mitigate biofuel stress and shows how tolerance genes can improve bacterial growth in the presence of toxic biofuel compounds. These identified genes can be targeted in future studies as candidates for use in biofuel production strains to increase biofuel yields.