Many biosurfactants show antimicrobial activity and some are found to be superior for isolating membrane proteins. This study was aimed towards a general understanding of the interactions of biosurfactants with lipid membranes on a molecular level. To this end, a new, fluorescence lifetime-based membrane leakage assay has been established that does not only quantify membrane permeabilization more precisely but reveals also the leakage mechanism. This mechanism, referred to as graded or all-or-none leakage, is crucial for interpreting potential biological activities and modes of action. Lipopeptides of the surfactin, fengycin, and iturin families as produced by Bacillus subtilis were studied along with synthetic surfactants. Their membrane permeabilizing activity and selectivity mirrored, to some extent, the active concentrations and fungicidal selectivity of the compounds in vivo. Furthermore, the effects of co-surfactants and co-solvents (glycerol, urea, DMSO) have been investigated to better understand and predict means of improving the performance of fungicidal products as well as conditions for membrane protein solubilization.

Orientador: Edério Dino Bidóia / Banca: Edson Aparecido Abdul Nour / Banca: Maria Aparecida Marin Morales / Resumo: A biodegradação tem sido há muito tempo um dos principais campos de pesquisa em microbiologia, cuja utilidade inclui a biodegradação de substâncias orgânicas e inorgânicas. Microrganismos podem ser ótimas ferramentas de remoção de poluentes em solo, água e sedimentos pelas suas inúmeras vantagens sobre outros processos. Para a limpeza de ambientes com hidrocarbonetos pela biorremediação deve-se explorar a habilidade dos microrganismos e compreender a maneira pela qual o processo ocorre em diferentes derivados do petróleo. Existem estudos que propõem a biorremediação de ambientes contaminados por hidrocarbonetos pela inoculação de microrganismos com potencial biodegradador e a adição de biossurfactantes. O presente trabalho estudou a biodegradação de diferentes derivados do petróleo com a proposta de aprimorar o processo pelo uso de biossurfactante produzido por Bacillus subtilis. Também foi avaliada a toxicidade das substâncias antes e depois da biodegradação. Os biossurfactantes produzidos foram adicionados aos ensaios de biodegradação de diferentes tipos de derivados do petróleo, incluindo óleo cru, compostos fenólicos, querosene, gasolina e óleos lubrificantes automotivos sintéticos e usados. Foram utilizados também, como comparação, óleos vegetais de soja e biodiesel. O estudo foi desenvolvido utilizando a técnica de respirometria a qual monitora a formação de CO2. Também foi utilizada a técnica de colorimetria pela análise da coloração do indicador redox DCPIP. Assim, a partir dos dados obtidos foram observados os diferentes perfis de biodegradação das diferentes substâncias, a fim de obter uma descrição de como a aplicação de biossurfactante produzido por B. subtilis afeta a biodegradação dos derivados do petróleo. Observou-se que a biodegradação dos derivados do petróleo ocorreu pela ação de consórcio de microrganismos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Biodegradation has been for a long time a main field of study in microbiology whose application includes organic and inorganic substances biodegradation. Microorganisms can be great pollutant removal tools in soil, water and sediments due to their advantages compared to other processes. In order to accomplish hydrocarbon-polluted environments cleanup by bioremediation, the microorganisms' capabilities must be exploited and studied, so then information on different petroleum byproducts can be achieved. Some studies propose environmental biorremediation not only by hydrocarbon-degrading microorganisms' insertion, but also by adding biossurfactants. In this work, different petroleum byproducts biodegradation was studied, aiming a biodegradation improvement through inclusion of a Bacillus subtilis produced biosurfactant. Biosurfactant production was also evaluated, as well as the substances toxicity before and after biodegradation. The biossurfactant produced was added to biodegradation assays of many different substances: crude oil, phenolic compounds, kerosene, gasoline and automotive lubricant oils. As a comparison, vegetable soy oils and biodiesel had their biodegradation performance evaluated. This study was developed by using the respirometric technique which is capable of evaluate CO2 production during biodegradation. Also, another biodegradation monitoring technique was used with a redox dye and colorimetry. Thus, from data obtained, different biodegradation profiles were estabilished and a precise description on how the biossurfactant affects petroleum byproducts biodegradation could be designed. It was observed that biodegradation occurred through microorganism consortium and B. subtilis. Also, the biossurfactant application yielded a better biodegradation. The mathematical modeling of the biodegradation process was also possible... (Complete abstract click electronic access below) / Mestre

[pt] A busca por novos reagentes de baixa toxicidade e de alta biodegradabilidade tem sido estimulada. Como resultado, diversas pesquisas vêm desenvolvendo biorreagentes, dentre eles os biossurfactantes. Os biossurfactantes são moléculas de origem microbiana que possuem ação superficial. Essas moléculas, com propriedades anfifílicas, são produzidas biologicamente e têm aplicação em diversos setores industriais. Assim sendo, esta pesquisa teve como objetivo estudar a flotação do sistema hematita-quartzo utilizando o biossurfactante solúvel produzido por Rhodococcus erythropolis como biorreagente coletor. O biossurfactante (BS) foi caracterizado por análises químicas para determinar a percentagem de proteínas, carboidratos e lipídeos e, suas propriedades físico-químicas foram determinadas por tensão superficial e concentração micelar crítica (CMC). Os minerais e sua interação com o BS foram caracterizados por medições de potencial zeta, medidas de ângulo de contato e espectroscopia no infravermelho (FTIR) para determinar suas propriedades eletrocinéticas, hidrofobicidade e grupos funcionais, respectivamente. Os resultados de adsorção revelaram maior adsorção do biossurfactante na superfície de hematita do que na superfície de quartzo e, isto foi confirmado por analises FTIR e testes de microflotação. Os resultados de microflotação de hematita e de quartzo foram maiores em pH 3 e com concentração de BS de 100 mg/L, com recuperações em torno de 99,88 por cento e 31,05 por cento, respectivamente e, os mesmos foram analisados estatisticamente para obter uma função polinomial representativa da microflotação. Os testes de microflotação do sistema hematita-quartzo mostraram que o biossurfactante é mais seletivo com hematita do que quartzo. O estudo cinético mostrou que os dados experimentais da microflotação de hematita foram ajustados quanto ao modelo cinético de primeira ordem como ao modelo cinético de ordem fracionária, enquanto os dados experimentais da microflotação de quartzo foram ajustados ao modelo cinético de ordem fracionária. Finalmente, os resultados deste trabalho evidenciaram que a utilização do biossurfactante solúvel produzido por Rhodococcus erythropolis como reagente coletor no sistema hematita-quartzo foi viável, demonstrando o seu grande potencial e mostrando- se bastante promissor para uma futura aplicação na indústria da flotação mineral. / [en] The search for new reagents of low toxicity and high biodegradability has been stimulated. As a result, several researches have been developing bioreagents, among them biosurfactants. Biosurfactants are molecules of microbial origin that have surface action. These molecules, with amphiphilic properties, are produced biologically and have application in various industrial sectors. Therefore, this research aimed to study the flotation of the hematite- quartz system using the soluble biosurfactant produced by Rhodococcus erythropolis as a collector bioreagent. The biosurfactant (BS) was characterized by chemical analysis to determine the percentage of proteins, carbohydrates and lipids and its physicochemical properties were determined by surface tension and critical micellar concentration (CMC). The minerals and their interaction with BS were characterized by measurements of zeta potential, contact angle measurements and infrared spectroscopy (FTIR) to determine their electrokinetic properties, hydrophobicity and functional groups, respectively. The adsorption results revealed higher adsorption of the biosurfactant onto the hematite surface than onto quartz surface and this was confirmed by FTIR analysis and microflotation tests. The results of hematite and quartz microflotation were higher at pH 3 and at the concentration of 100 mg/L, with recoveries around 99.88 percent and 31.05 percent, respectively, and they were analyzed statistically to obtain a polynomial function representative of microflotation. The microflotation tests of the hematite-quartz system showed that the biosurfactant is more selective with hematite than quartz. The kinetic study showed that the experimental data of hematite microflocation were adjusted to both the first order kinetic model and the kinetic model of non-integral order, while the experimental data of the quartz microflotation were adjusted to the kinetic model of non-integral order. Finally, the results of this work showed that the use of the soluble biosurfactant produced by Rhodococcus erythropolis as a collector reagent in the hematite-quartz system was feasible, demonstrating its great potential and showing quite promising for a future application in the mineral flotation industry.

La récupération assistée des hydrocarbures par des microorganismes (MEOR) est une technologie potentiellement utilisable pour améliorer l’efficacité de l’extraction pétrolière. Cette technique utilise les capacités métaboliques de certaines souches bactériennes pour récupérer les huiles des réservoirs. Cependant, le manque de connaissances sur la physiologie et les activités métaboliques des microorganismes des réservoirs est un obstacle majeur pour le développement de cette approche. L’objectif de ce travail était d’étudier la physiologie des microorganismes indigènes de réservoirs pétroliers, en déterminant leurs capacités métaboliques, leurs conditions de croissances et leur positionnement taxonomique. Pour cela, trois activités physiologiques d’intérêt pour la MEOR : (1) la dégradation de l’hexadécane ;(2) la production de biosurfactant et (3) la formation de biofilm ont été évaluées sur 84 souches bactériens anaérobies isolées exclusivement de plusieurs réservoirs pétroliers. Ces isolats appartiennent à deux groupes métaboliques : les bactéries sulfato-réductrices (BSR) et les anaérobies fermentaires. Ainsi, cette prospection à donner une image de la diversité des souches de réservoirs possédant des activités appropriées pour la MEOR. Le séquençage et l’analyse phylogénétique du gène codant pour L’ARNr 16S a permet d’identifier deux nouvelles espèces bactériennes d’anaérobies fermentaires, SRL 4223 et SRL 4209 capables de produire des biosurfactants. Ainsi la caractérisation de ces deux isolats a révélé que la souche SRL 4223 présentait toutes les caractéristiques phénotypiques et génétiques autorisant sa classification un nouveau genre nommé Pleomorphochaeta caudata et que la souche SRL 4209 peut être affilié comme une nouvelle espèce de ce nouveau genre. / The Microbial enhanced oil recovery (MEOR) is a potentially useful technology to improve the efficiency of oil extraction. This technique utilizes microorganisms and/or their metabolites (biosurfactants, polymers, biomass…etc.) to recover oil from reservoirs. However, the lack of basic knowledge about physiology and metabolic capacities of reservoir microorganisms is a major obstacle for the development of this approach. The objective of this work was to study the physiology of indigenous reservoir microorganisms by determining their metabolic capacities, their growth conditions and their taxonomic position. For this, three activities related to MEOR: (1) hexadecane degradation; (2) biofilm formation and (3) biosurfactant production were evaluated on 84 anaerobic bacterial strains isolated exclusively from several petroleum reservoirs. These isolates belong to two metabolic groups: sulfate-reducing bacteria (SRB) and anaerobic fermentative bacteria. This study gives a picture of the diversity of indigenous strains possessing proper activities for MEOR. Sequencing and phylogenetic analysis of 16S rRNA gene identified two new species of fermentative bacteria: SRL 4223 and SRL 4209, capable of producing biosurfactants. Characterization of these isolates revealed that the strain SRL 4223 had all the phenotypic and genetic characteristics allowing its classification as a new genus named Pleomorphochaeta caudata and the strain SRL 4209 was affiliated as a new species of this genus.

The present study investigated the feasibility of production of sophorolipids (SLs) using yeast Candida bombicola grown on hydrolysates derived lignocellulosic feedstock either with or without supplementing oil as extra carbon source. Several researchers have reported using pure sugars and various oil sources for producing SLs which makes them expensive for scale-up and commercial production. In order to make the production process truly sustainable and renewable, we used feedstocks such as sweet sorghum bagasse, corn fiber and corn stover. Without oil supplementation, the cell densities at the end of day-8 was recorded as 9.2, 9.8 and 10.8 g/L for hydrolysate derived from sorghum bagasse, corn fiber, and corn fiber with the addition of yeast extract (YE) during fermentation, respectively. At the end of fermentation, the SL concentration was 3.6 g/L for bagasse and 1.0 g/L for corn fiber hydrolysate. Among the three major sugars utilized by C. bombicola in the bagasse cultures, glucose was consumed at a rate of 9.1 g/L-day; xylose at 1.8 g/L-day; and arabinose at 0.98 g/L-day. With the addition of soybean oil at 100 g/L, cultures with bagasse hydrolysates, corn fiber hydrolysates and standard medium had a cell content of 7.7 g/L; 7.9 g/L; and 8.9 g/L, respectively after 10 days. The yield of SLs from bagasse hydrolysate was 84.6 g/L and corn fiber hydrolysate was15.6 g/L. In the same order, the residual oil in cultures with these two hydrolysates was 52.3 g/L and 41.0 g/L. For this set of experiment; in the cultures with bagasse hydrolysate; utilization rates for glucose, xylose and arabinose was recorded as 9.5, 1.04 and 0.08 g/L-day respectively. Surprisingly, C. bombicola consumed all monomeric sugars and non-sugar compounds in the hydrolysates and cultures with bagasse hydrolysates had higher yield of SLs than those from a standard medium which contained pure glucose at the same concentration. Based on the SL concentrations and considering all sugars consumed, the yield of SLs was 0.55 g/g carbon (sugars plus oil) for cultures with bagasse hydrolysates. Further, SL production was investigated using sweet sorghum bagasse and corn stover hydrolysates derived from different pretreatment conditions. For the former and latter sugar sources, yellow grease or soybean oil was supplemented at different doses to enhance sophorolipid yield. 14-day batch fermentation on bagasse hydrolysates with 10, 40 and 60 g/L of yellow grease had cell densities of 5.7 g/L, 6.4 g/L and 7.8 g/L, respectively. The study also revealed that the yield of SLs on bagasse hydrolysate decreased from 0.67 to 0.61 and to 0.44 g/g carbon when yellow grease was dosed at 10, 40 and 60 g/L. With aforementioned increasing yellow grease concentration, the residual oil left after 14 days was recorded as 3.2 g/L, 8.5 g/L and 19.9 g/L. For similar experimental conditions, the cell densities observed for corn stover hydrolysate combined with soybean oil at 10, 20 and 40 g/L concentration were 6.1 g/L, 5.9 g/L, and 5.4 g/L respectively. Also, in the same order of oil dose supplemented, the residual oil recovered after 14-day was 8.5 g/L, 8.9 g/L, and 26.9 g/L. Corn stover hydrolysate mixed with the 10, 20 and 40 g/L soybean oil, the SL yield was 0.19, 0.11 and 0.09 g/g carbon. Overall, both hydrolysates supported cell growth and sophorolipid production. The results from this research show that hydrolysates derived from the different lignocellulosic biomass feedstocks can be utilized by C. bombicola to achieve substantial yields of SLs. Based upon the results revealed by several batch-stage experiments, it can be stated that there is great potential for scaling up and industrial scale production of these high value products in future.

Made available in DSpace on 2014-06-11T19:27:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-03-16Bitstream added on 2014-06-13T20:47:50Z : No. of bitstreams: 1 montagnolli_rn_me_rcla.pdf: 5963481 bytes, checksum: 742a43c637266a3cc9d7e7657043ccd7 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A biodegradação tem sido há muito tempo um dos principais campos de pesquisa em microbiologia, cuja utilidade inclui a biodegradação de substâncias orgânicas e inorgânicas. Microrganismos podem ser ótimas ferramentas de remoção de poluentes em solo, água e sedimentos pelas suas inúmeras vantagens sobre outros processos. Para a limpeza de ambientes com hidrocarbonetos pela biorremediação deve-se explorar a habilidade dos microrganismos e compreender a maneira pela qual o processo ocorre em diferentes derivados do petróleo. Existem estudos que propõem a biorremediação de ambientes contaminados por hidrocarbonetos pela inoculação de microrganismos com potencial biodegradador e a adição de biossurfactantes. O presente trabalho estudou a biodegradação de diferentes derivados do petróleo com a proposta de aprimorar o processo pelo uso de biossurfactante produzido por Bacillus subtilis. Também foi avaliada a toxicidade das substâncias antes e depois da biodegradação. Os biossurfactantes produzidos foram adicionados aos ensaios de biodegradação de diferentes tipos de derivados do petróleo, incluindo óleo cru, compostos fenólicos, querosene, gasolina e óleos lubrificantes automotivos sintéticos e usados. Foram utilizados também, como comparação, óleos vegetais de soja e biodiesel. O estudo foi desenvolvido utilizando a técnica de respirometria a qual monitora a formação de CO2. Também foi utilizada a técnica de colorimetria pela análise da coloração do indicador redox DCPIP. Assim, a partir dos dados obtidos foram observados os diferentes perfis de biodegradação das diferentes substâncias, a fim de obter uma descrição de como a aplicação de biossurfactante produzido por B. subtilis afeta a biodegradação dos derivados do petróleo. Observou-se que a biodegradação dos derivados do petróleo ocorreu pela ação de consórcio de microrganismos... / Biodegradation has been for a long time a main field of study in microbiology whose application includes organic and inorganic substances biodegradation. Microorganisms can be great pollutant removal tools in soil, water and sediments due to their advantages compared to other processes. In order to accomplish hydrocarbon-polluted environments cleanup by bioremediation, the microorganisms’ capabilities must be exploited and studied, so then information on different petroleum byproducts can be achieved. Some studies propose environmental biorremediation not only by hydrocarbon-degrading microorganisms’ insertion, but also by adding biossurfactants. In this work, different petroleum byproducts biodegradation was studied, aiming a biodegradation improvement through inclusion of a Bacillus subtilis produced biosurfactant. Biosurfactant production was also evaluated, as well as the substances toxicity before and after biodegradation. The biossurfactant produced was added to biodegradation assays of many different substances: crude oil, phenolic compounds, kerosene, gasoline and automotive lubricant oils. As a comparison, vegetable soy oils and biodiesel had their biodegradation performance evaluated. This study was developed by using the respirometric technique which is capable of evaluate CO2 production during biodegradation. Also, another biodegradation monitoring technique was used with a redox dye and colorimetry. Thus, from data obtained, different biodegradation profiles were estabilished and a precise description on how the biossurfactant affects petroleum byproducts biodegradation could be designed. It was observed that biodegradation occurred through microorganism consortium and B. subtilis. Also, the biossurfactant application yielded a better biodegradation. The mathematical modeling of the biodegradation process was also possible... (Complete abstract click electronic access below)

Orientador: Jonas Contiero / Banca: Henrique Ferreira / Banca: Francisco José dos Santos / Banca: José Gregório Cabrera Gomez / Banca: Humberto Marcio Santos Milagre / Resumo: Os biossurfactantes são metabólitos secundários que apresentam atividade de superfície, podendo ser aplicados em diferentes processos industriais, como produção de fármacos, compostos químicos, cosméticos, biorremediação de ambientes poluídos por petróleo e derivados e recuperação terciária do petróleo. A maior vantagem destes compostos quando comparado aos surfactantes sintéticos reside na sua diversidade estrutural, baixa toxicidade e alta biodegradabilidade. Apesar das inúmeras vantagens apresentadas pelos biotensoativos, eles não são comercialmente utilizados devido ao alto custo de produção. O objetivo deste trabalho foi estudar a produção de ramnolipídios por mutantes de P. aeruginosa a partir de resíduos industriais e óleos vegetais, bem como caracterizar as propriedades de solução desses biossurfactante, além de verificar a influência da fonte de carbono na produção de homólogos de ramnolipídios por P. aeruginosa. Na primeira etapa as fermentações foram conduzidas em tubos de ensaio, após a seleção dos micro-organismos com potencial para alta produção, os mesmos foram testados em frascos Erlenmeyer. O mutante com potencial para elevada produção foi avaliado, junto com a linhagem selvagem, em fermentadores. A linhagem selecionada e a utilização do meio de cultura livre de cálcio contendo óleo de girassol como fonte de carbono acarretou em um aumento de 70% na produção de ramnolipídios. A adição de etanol às soluções de ramnolipídios comprovou o potencial desse tensoativo para serem aplicados na indústria de cosméticos, já que as propriedades de tensão superficial, agregação e emulsificação foram mantidas nas três concentrações de álcool adicionadas. Além disso, verificou-se que a mudança da fonte de carbono acarreta alteração nos tipos ácidos graxos e proporções de homólogos de ramnolipídios produzidos por P. aeruginosa LBI 2A1 / Abstract: The biosurfactants are secondary metabolites that exhibit surface activity and can be applied in different industrial processes such as production of pharmaceuticals, chemicals, cosmetics, bioremediation of environments polluted by oil and derivatives and tertiary recovery of oil. The greatest advantage of these compounds compared to synthetic surfactants lies in their structural diversity, low toxicity and high biodegradability. Despite the numerous advantages provided by biosurfactants, they are not commercially used due to the high cost of production. The present study aimed to evaluate the production of rhamnolipids by mutants of P. aeruginosa using industrial waste and vegetable oils as carbon source, as well as to characterize the properties of these biosurfactant solutions and investigate the influence of carbon source in the production of homologous rhamnolipds by P. aeruginosa. In the first stage fermentations were conducted in test tubes, after selection of microorganisms with potential for high production they were tested in Erlenmeyer flasks. The mutant with the potential for increased production was assessed, along with the wild strain in bioreactors. The selected strain and the calcium free medium used with sunflower oil as carbon source resulted in an 70% increase in the production of rhamnolipids. The addition of ethanol to the rhamnolipids solutions proved the potential of this biosurfactant to be applied in the cosmetic industry, since the properties of surface tension, emulsification and aggregation were held in all three concentrations of ethanol added. Moreover, it was found that changing the carbon source caused alteration in the types of fatty acids and rhamnolipids counterparts proportions produced by P. aeruginosa LBI 2A1 / Doutor

Thesis submitted in fulfilment of the requirements for the degree of Doctor Technologiae: Chemical Engineering, Faculty of Engineering at the Cape Peninsula University of Technology - Cape Town, South Africa / Polycyclic aromatic hydrocarbons (PAHs) are one of the most common and recalcitrant environmental contaminants – known for their potential toxicity, mutagenicity, and carcinogenicity to humans. Biosurfactant application can enhance the biodegradation of PAHs. The main object of this work was to explore the novelty of biosurfactant produced by the isolated strains of Bacillus sp and Pseudomonas aeruginosa grown exclusively on Beta vulgaris, and the modification of the zeolites nanoparticles by the biosurfactant, for enhanced biodegradation of PAHs in soil. Novel biosurfactant-producing strains were isolated from hydrocarbon-contaminated environments, while several agrowaste were screened as primary carbon sources for the expression of biosurfactants, which were quantified using various standardized methods......

AgÃncia Nacional do PetrÃleo / A grande procura por surfactantes quÃmicos no mercado tem aumentado o interesse em biossurfactantes, substÃncias biodegradÃveis produzidas por bactÃrias, leveduras e fungos. Neste contexto, este trabalho tem como objetivo estudar a produÃÃo de biossurfactante por cepa isolada de manguezal cearense, bem como avaliar as propriedades funcionais e aplicabilidade do produto formado. Os resultados mostraram que o biossurfactante produzido pela cepa ICA56, em meio mineral, foi capaz de reduzir a tensÃo superficial da Ãgua de 72 para 30 mN.m-1 e interfacial de um sistema Ãgua/gasolina de 15 para 3 mN.m-1, mostrando sua eficiÃncia como tensoativo. O biossurfactante produzido foi capaz de produzir emulsÃo estÃvel em algumas fontes hidrofÃbicas, tais como, Ãleo de motor, Ãleo de soja, hexano e querosene. As propriedades emulsificante e tensoativas do bioproduto formado no cultivo da cepa ICA56 mostraram-se estÃveis frente Ãs variaÃÃes de pH, temperatura e concentraÃÃo salina, mostrando indÃcios de sua ampla aplicabilidade. Outro resultado que comprova a eficiÃncia do biossurfactante produzido à a sua concentraÃÃo micelar crÃtica em torno de 25 mg.L-1. O biossurfactante produzido foi capaz de remover hidrocarbonetos e metais pesados em sistemas que simulavam ambientes contaminados, apresentando eficiÃncia, quando comparado aos surfactantes quÃmicos. Apesar da eficiÃncia das propriedades funcionais e aplicabilidade do biossurfactante, a produÃÃo em meio mineral era em torno de 200 mg.L-1, sendo esta uma concentraÃÃo razoÃvel. Foram avaliadas duas alternativas para o aumento da produÃÃo de biossurfactante: a influÃncia transferÃncia de oxigÃnio em biorreator de bancada e a utilizaÃÃo de substratos nÃo convencionais. A variaÃÃo da agitaÃÃo e aeraÃÃo em biorreator de bancada nÃo apresentou um resultado tÃo significativo, mostrando que a condiÃÃo operacional de 200 rpm de agitaÃÃo e 1 L.min-1 de aeraÃÃo foi a melhor, dentre as avaliadas, para a produÃÃo de biossurfactante. Jà a utilizaÃÃo de substratos nÃo convencionais mostrou-se como uma melhor alternativa para aumentar a produÃÃo, pois alÃm de reduzir custos no processo, foram observados maiores rendimentos do que no meio sintÃtico. Substratos como Ãleo de girassol e glicerol sÃo apresentados como potenciais fontes de carbono para produÃÃo de biossurfactante pela cepa ICA56, obtendo concentraÃÃes de 870 mg.L-1 e 1420 mg.L-1 do produto de interesse, na sua forma bruta, respectivamente. / The high demand for chemical surfactants in the worldwide market has increased the interest on biosurfactants, which are biodegradable substances produced by bacteria, yeasts and fungi. In this context, this work aims to study the biosurfactant production by a strain isolated from a Brazilian mangrove, as well evaluate its functional properties and applicability. The results has presented that the biosurfactant produced by strain ICA56, in mineral medium, was capable to reduce the surface tension of water from 72 to 30 mN.m-1 and interfacial tension on a water/gasoline system from 15 to 3 mN.m-1, showing its efficiency as a tensoative. The biosurfactant was capable to produce stable emulsion on some hydrophobic sources, as motor oil, soybean oil, hexane and kerosene. The emulsifying and tensoative properties of the bioproduct formed on ICA56âs cultivation have showed some stability through the environmental variations of pH, temperature and saline concentration, presenting some evidences of its wide applicability. Another result which proves the efficiency for the biosurfactant produced is the critical micelle concentration around 25 mg.L-1. The biosurfactant produced was able to remove hydrocarbons and heavy metals in contaminated environments simulating systems, presenting efficiency when itâs compared to chemical surfactants. Despite the efficiency of the functional properties and applicability of the biosurfactant, the production in mineral medium was around 200 mg.L-1, which is a reasonable concentration. So, it was evaluated 2 alternatives in order to increase the biosurfactant production: the influence of oxygen transfer and the use of unconventional substrates. The variation of agitation and aeration in bioreactor didnât seemed to present such a significant result, showing that the operational condition of 200 rpm for agitation and 1 L.min-1 for aeration was the best among the tested conditions for biosurfactant production. However, the use of unconventional substrates proved to be a better alternative in order to increase the biosurfactant production, as well as reducing costs in the process, as higher yields were observed in comparison to mineral medium. Substrates such as sunflower oil and glycerol are presented as potential carbon sources for biosurfactant production by strain ICA56, obtaining concentrations of 870 mg.L-1 and 1420 mg.L-1 of the product of interest, in its raw form, respectively.

Submitted by (lucia.rodrigues@ufrpe.br) on 2016-05-25T15:09:43Z No. of bitstreams: 1 Ana Paula Pereira dos Santos.pdf: 4015984 bytes, checksum: 9b75fca220d52dcc5eaf8ac82ee6d0a3 (MD5) / Made available in DSpace on 2016-05-25T15:09:43Z (GMT). No. of bitstreams: 1 Ana Paula Pereira dos Santos.pdf: 4015984 bytes, checksum: 9b75fca220d52dcc5eaf8ac82ee6d0a3 (MD5) Previous issue date: 2013-02-28 / Biosurfactants are amphiphilic molecules produced by micro-organisms that consist of a hydrophilic portion and a hydrophobic portion. The hydrophilic portion consists of mono-oligo-or polysaccharides, proteins or peptides and the hydrophobic portion contains saturated, unsaturated and hydroxy fatty acids or alcohols. Many micro-organisms produce surfactants with antibacterial, antifungal, antitumor, antiparasitic and herbicide use in medicine and agriculture. In this sense, producing a biosurfactant by Streptomyces sp. DPUA1559 isolated Amazon region, grown in medium containing soybean oil and waste frying peptone was performed using a 22 factorial design to investigate the effects and interactions on the response variables surface tension, emulsification index and production yield. The production of the biosurfactant was confirmed by reduction of surface tension. The critical micelle concentration (CMC) was 10 mg/ml and the average surface tension at the focal point was about 25,34 mN/m in a yield of 1,17 g/l. The isolated biosurfactant showed emulsification index 89% to 95% engine oil and engine oil residual. The kerosene emulsification showed a 40%, while the diesel oil was not emulsified effectively. For vegetable oils (corn, canola, soybean, and sunflower) emulsion was formed around 47%. The isolated biosurfactant was stable when subjected to extreme environmental conditions of pH, temperature and NaCl concentration and showed no toxicity when tested against the micro-crustacean Artemia salina and seeds of vegetables lettuce (Lactuca sativa L.) and cabbage (Brassica oleracea L.). The characterization of biomolecule analysis demonstrated the chemical composition of 20% protein and 38% carbohydrate. Molecular characterization on polyacrylamide gel electrophoresis SDS-PAGE showed the biosurfactant a single protein band and 14.3kDa character acid. The spectral analysis method by FT-IR-Atr revealed a chemical structure composed mainly of peptides with different polarities. The strains of Microsporum canis isolates from dogs superficial mycoses were susceptible in the presence of biosurfactant isolated presenting a growth inhibition at concentrations of 1.9 to 1000 μg/ml. / Biossurfactantes são moléculas anfifílicas produzidas por micro-organismos que consistem em uma porção hidrofílica e uma porção hidrofóbica. A porção hidrofílica é constituída por mono-oligo ou polissacarídeos, peptídeos ou proteínas e a porção hidrofóbica contém saturado, insaturado e hidroxilados de ácidos graxos ou álcoois. Muitos micro-organismos produzem surfactantes com atividade antibacteriana, antifúngica, antitumoral, antiparasitária e herbicida com uso na medicina e agricultura. Neste sentido, a produção de um biossurfactante por Streptomyces sp. DPUA1559 isolado da Região Amazônica, cultivado em meio contendo óleo de soja residual de fritura e peptona, foi realizada utilizando-se um planejamento fatorial 22 para verificar os efeitos e interação sobre as variáveis respostas tensão superficial, índice de emulsificação e rendimento de produção. A produção do biossurfactante foi confirmada pela redução da tensão superficial. A concentração micelar crítica (CMC) foi de 10 mg/ml e a média da tensão superficial no ponto central foi em torno de 25,34 mN/m com um rendimento de 1,17 g/l. O biossurfactante produzido apresentou índice de emulsificação 89% para óleo de motor e 95% óleo de motor residual. O querosene apresentou uma emulsificação de 40%, enquanto o óleo diesel não foi efetivamente emulsificado. Para os óleos vegetais (milho, canola, soja e girassol) a emulsão formada foi em torno de 47%. O biossurfactante produzido mostrou estabilidade quando submetido a condições ambientais extremas de pH, temperatura e concentração de NaCl e não apresentou toxicidade quando testado frente ao micro-crustáceo Artemia salina e às sementes dos vegetais alface (Lactuca sativa L.) e repolho (Brassica oleracea L.). A analise da caracterização da biomolécula demostrou na sua composição química 20% de proteína e 38% de carboidrato. Na caracterização molecular em eletroforese de gel de poliacrilamida SDS-PAGE o biossurfactante mostrou uma única banda proteica 14,3 kDa e caráter ácido. A análise espectral pelo método FT-IR-Atr revelou uma estrutura química composta basicamente por peptídeos, com polaridades diferentes. As linhagens de Microsporum canis isolados de micoses superficiais de cães foram susceptíveis na presença do biossurfactante isolado, apresentando uma inibição de crescimento a partir da concentração de 1,9 a 1000 μg/ml.