<i>Rhodococcus equi</i> (<i>R. equi</i>) is an intracellular, gram-positive coccobacillus that causes pneumonia in foals aged 2 to 4 months. Neonatal foals are susceptible to <i>R. equi</i> infection probably due to inefficient Toll-like receptor (TLR)-2 signaling and inability to produce interferon gamma. One of the reasons for inefficient receptor signaling and recognition of <i>R. equi</i> by the foals immune system may be the inefficient sequestration of TLRs in lipid rafts, which act as signaling platforms. However, there are no protocols to isolate lipid rafts from equine cells and, therefore, no data on the association of TLRs with the lipid rafts in the lung cells of normal and infected foals. Because of the clinical importance of the disease, there is considerable interest in developing effective prophylactic methods, which in turn requires a better understanding of fundamental immunology of the foals. In this study, I have examined the effect of <i>R. equi</i> vaccination on the lung inflammation induced following challenge with <i>R. equi</i>. I also developed a protocol to isolate lipid rafts from broncho-alveolar lavage (BAL) cells and investigated the association of lipid rafts with TLRs.<p> In the first study, 15 mixed breed draft-type foals up to 7 weeks of age were studied. The foals were divided into control (n=7) and a vaccinated (n=8). The control foals were given 10 mL phosphate buffered saline intramuscularly while the vaccinated group was vaccinated on day 0 of the study followed by a booster on day 14. All the foals were challenged with <i>R. equi</i> (5x106 cells/mL into the dorso-caudal region of the right lung lobe). BAL was performed on day 14, 28 and 35 and all the foals were euthanized on day 49 of the study.<p> The study design did not leave any non-infected foal at the end of the experiment. Therefore, lung samples were obtained from two untreated control (non-vaccinated non-infected) foals from the Department of Veterinary Pathology, University of Saskatchewan were used. The data showed similar levels of lung inflammation in both the control and vaccinated foal groups based on BAL cytology, gross pathology and histopathology. Gross and histopathological studies indicated that both control and vaccinated foals developed granulomatous lesions. Immunohistology showed increased expression of TLR4, TLR2 and TNF alpha in alveolar septa and in some cases in the vascular endothelium and airway epithelium in the lungs of both groups compared to the untreated control foals. Western blots showed increased expression of TLR2 but not TLR4 in the lung extracts from both the vaccinated and the control foals. Vaccinated foals showed higher concentrations of TNF alpha(p=0.0219) in their BAL on day 28 but lower concentrations of IL-10 (p=0.0172) in their lung extracts collected on day 49 compared to the controls. There were no differences in IFN gamma and protein concentrations between the two groups.<p> To understand the role of lipid rafts in TLR4 and TLR2 signaling, I developed an efficient and simpler protocol to isolate lipid rafts from BAL cells of foals and confirmed their identity by localizing Flotillin-1 and GM-1 (fractions 6-9), which are lipid raft markers, and transferrin receptor (fractions 1-4) which is present in non-lipid raft fractions. Lung macrophages from naïve foals lacked sequestration of Flotillin-1 and GM-1 in the higher fractions compared to the vaccinated foals. Further, the data showed that while TLR4 and TLR2 were localized in most of the fractions (1-9) in control foal BAL collected on day 14 and 28, the TLR4 and TLR2 association was restricted to fractions 6-9 in the lipid rafts isolated from BAL cells of vaccinated foals. These data suggest that BAL cells of neonatal foals may not have effective signaling machinery because of lack of association of TLR2 and TLR4 with lipid rafts.<p> Taken together, the data show similar levels of lung inflammation in the control and vaccinated foals upon infection with <i>R. equi</i>. The vaccination, however, appeared to have some effect on the immunohistologic expression of TLR2, TLR4 and TNFalpha in the lung tissues, and increased association of TLR2 and TLR4 with the lipid raft fractions. Based on the higher expression of TNF alpha and lower expression of IL-10, the vaccinated foals may be more competent to mount an immune response against <i>R. equi</i>.

Rhodococcus is an important industrial organism that possesses diverse metabolic capabilities, it also has a unique cell envelope, composed of an outer layer of mycolic acids and glycolipids (free or bound lipids generally linked to the sugar trehalose). Rhodococcus is able to transform nitriles to the corresponding amide by the enzyme Nitrile Hydratase (NHase), therefore rhodococcal cells can be utilized as biocatalysts in the detoxification of nitrile waste water or in the production of industrially important amides such as acrylamide. However, the NHase within the native cells must be stable with high activity. This research examined how NHase activity and stability can be increased in native cells by changing growth media composition, the impact on the rhodococcal cell envelope was also studied. Growth media composition was altered by supplementing different sugars such as fructose, maltose or maltodextrin to replace glucose in rich solid media containing cobalt and urea for induction of NHase. The supplementation of maltose or maltodextrin resulted in significantly higher NHase activities and greater NHase stability at 55„aC. The supplementation of these different sugars was shown to alter cellular and lipid bound trehalose levels, a sugar known to stabilize proteins and a component of the rhodococcal cell envelope. Cells that had higher levels of cellular trehalose had significantly greater NHase stability at 55„aC. The effect of the different sugar supplements and inducers of NHase, such as cobalt, on cell envelope components such as mycolic acids and glycolipids were examined by High Performance Liquid Chromatography (HPLC) and Thin Layer Chromatography (TLC). The results showed that changes in mycolic acids and glycolipids occurred when the cells were grown in the presence of different sugar supplements and when the cells were induced for NHase. Susceptibility of Rhodococcus sp DAP 96253 to different antibiotics was examined to indicate if changes were occurring in the cell envelope. Differences in antibiotic susceptibility were observed when the cells were grown on media with different sugar supplements and when the cells were induced for NHase. In the presence of cobalt Rhodococcus sp DAP 96253 showed a significant increase in sensitivity to antibiotics. Changes in growth media composition influences the cell envelope of Rhodococcus sp DAP 96253 and also affects NHase activity and stability. Therefore, achieving increased enzyme activity and stability is not entirely dependent on the actual enzyme, but is related to other aspects of the cell, such as the cell envelope and metabolites of the cell.

<i>Rhodococcus equi</i> (<i>R. equi</i>) is an intracellular, gram-positive coccobacillus that causes pneumonia in foals aged 2 to 4 months. Neonatal foals are susceptible to <i>R. equi</i> infection probably due to inefficient Toll-like receptor (TLR)-2 signaling and inability to produce interferon gamma. One of the reasons for inefficient receptor signaling and recognition of <i>R. equi</i> by the foals immune system may be the inefficient sequestration of TLRs in lipid rafts, which act as signaling platforms. However, there are no protocols to isolate lipid rafts from equine cells and, therefore, no data on the association of TLRs with the lipid rafts in the lung cells of normal and infected foals. Because of the clinical importance of the disease, there is considerable interest in developing effective prophylactic methods, which in turn requires a better understanding of fundamental immunology of the foals. In this study, I have examined the effect of <i>R. equi</i> vaccination on the lung inflammation induced following challenge with <i>R. equi</i>. I also developed a protocol to isolate lipid rafts from broncho-alveolar lavage (BAL) cells and investigated the association of lipid rafts with TLRs.<p> In the first study, 15 mixed breed draft-type foals up to 7 weeks of age were studied. The foals were divided into control (n=7) and a vaccinated (n=8). The control foals were given 10 mL phosphate buffered saline intramuscularly while the vaccinated group was vaccinated on day 0 of the study followed by a booster on day 14. All the foals were challenged with <i>R. equi</i> (5x106 cells/mL into the dorso-caudal region of the right lung lobe). BAL was performed on day 14, 28 and 35 and all the foals were euthanized on day 49 of the study.<p> The study design did not leave any non-infected foal at the end of the experiment. Therefore, lung samples were obtained from two untreated control (non-vaccinated non-infected) foals from the Department of Veterinary Pathology, University of Saskatchewan were used. The data showed similar levels of lung inflammation in both the control and vaccinated foal groups based on BAL cytology, gross pathology and histopathology. Gross and histopathological studies indicated that both control and vaccinated foals developed granulomatous lesions. Immunohistology showed increased expression of TLR4, TLR2 and TNF alpha in alveolar septa and in some cases in the vascular endothelium and airway epithelium in the lungs of both groups compared to the untreated control foals. Western blots showed increased expression of TLR2 but not TLR4 in the lung extracts from both the vaccinated and the control foals. Vaccinated foals showed higher concentrations of TNF alpha(p=0.0219) in their BAL on day 28 but lower concentrations of IL-10 (p=0.0172) in their lung extracts collected on day 49 compared to the controls. There were no differences in IFN gamma and protein concentrations between the two groups.<p> To understand the role of lipid rafts in TLR4 and TLR2 signaling, I developed an efficient and simpler protocol to isolate lipid rafts from BAL cells of foals and confirmed their identity by localizing Flotillin-1 and GM-1 (fractions 6-9), which are lipid raft markers, and transferrin receptor (fractions 1-4) which is present in non-lipid raft fractions. Lung macrophages from naïve foals lacked sequestration of Flotillin-1 and GM-1 in the higher fractions compared to the vaccinated foals. Further, the data showed that while TLR4 and TLR2 were localized in most of the fractions (1-9) in control foal BAL collected on day 14 and 28, the TLR4 and TLR2 association was restricted to fractions 6-9 in the lipid rafts isolated from BAL cells of vaccinated foals. These data suggest that BAL cells of neonatal foals may not have effective signaling machinery because of lack of association of TLR2 and TLR4 with lipid rafts.<p> Taken together, the data show similar levels of lung inflammation in the control and vaccinated foals upon infection with <i>R. equi</i>. The vaccination, however, appeared to have some effect on the immunohistologic expression of TLR2, TLR4 and TNFalpha in the lung tissues, and increased association of TLR2 and TLR4 with the lipid raft fractions. Based on the higher expression of TNF alpha and lower expression of IL-10, the vaccinated foals may be more competent to mount an immune response against <i>R. equi</i>.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 4 uppsatser.

Universiẗat, Diss., 1999--Stuttgart.

Orientador: José Correa de Lacerda Neto / Banca: Rosangela Zacarias Machado / Banca: Wilson Roberto Fernandes / Resumo: A transferência de imunidade passiva, através da ingestão do colostro é um fator de grande importância para a sobrevivência de potros neonatos. O colostro é rico em imunoglobulinas, que constitui para esses animais a única fonte de proteção contra os agentes infecciosos durante o período neonatal, fase em que os animais apresentam maior susceptibilidade às doenças. Dentre estas, destaca-se a infecção ocasionada pelo Rhodococcus equi, responsável por elevadas taxas de mortalidade e grandes perdas econômicas. A infecção possui distribuição mundial e causa pneumonia supurativa e enterite associada a linfadenite em potros com menos de seis meses de idade. Apesar da sua grande importância no Brasil, a rodococose ainda é pouco estudada em nossas condições. O objetivo deste estudo foi comparar a resposta imune humoral entre éguas das raças Brasileiro de Hipismo (BH) e Bretã previamente imunizadas para R. equi, e avaliar o efeito da imunoprofilaxia ativa materna na transferência de anticorpos específicos protetores, via colostro, para neonatos eqüinos, utilizando na detecção de anticorpos o ensaio imunoenzimático indireto (ELISA teste), comparando dois diferentes antígenos (APTX e comercial). Os resultados demonstraram que ocorreu aumento na titulação de anticorpos anti-Rhodococcus equi nos grupos de éguas após a vacinação e transferência de anticorpos através do colostro para os potros neonatos. Não houve efeito da raça na produção de anticorpos. O antígeno comercial detectou títulos de anticorpos maiores e mais persistentes do que o antígeno APTX... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: The passive immunity transfer through colostrum is very important to new-born foals survival. The colostrum is immunoglobulin full, wich is responsable to protect against infectious agents during new-born period, stage that animals present higher susceptibility to diseases. Among these, the infection caused by Rhodococcus equi has the great importance, responsable for large economics damage and high mortality rates in animals illness. The infection has a world-wide distribuition and it causes suppurative pneumonia and enterits associated to limphadenitis in foals under 6 months old. Although its great importance in Brazil, this disease is not well studied. The aims of this study was to compare the humoral immune respost between the breeds "Brasileiro de hipismo" (BH) and Breton, previously vaccinated against Rhodococcus equi, and to evaluate the matern immunoprofilaxy effect in the specific antibodies transfer through colostrum to new-born foals, using the Enzyme linked immunosorbent assay (ELISA-test) comparing two differents antigens ("APTX" and comercial"). The results demonstrated that there were an increase in mares antibodies after vaccination and also antibodies transfer through colostrum to new-born foals. There was no breed effect in the antibodies production. The Comercial antigen demonstrated antibodies titulation higher and more persistents than APTX antigen. The ELISA-test demonstrated sensible R. equi antibodies determination. / Mestre

Structural biology is one of the most quickly growing fields of research in life sciences. X-ray diffraction analysis is the technique that allows direct visualization of protein structure at the atomic or near-atomic level. Structure solution of proteins and protein complexes by X-ray crystallography provides important insights into their mode of action. The haloalkane dehalogenase proteins represent objects of interest for protein engineering studies, attempting to improve their catalytic efficiency or broaden their substrate specificity towards environmental pollutants. In the present study, the structures of three haloalkane dehalogenase DhaA mutants DhaA04, DhaA14 and DhaA15 at atomic resolution are reported and compared to explore the effect of mutations on the enzymatic activity of modified proteins from a structural perspective. Besides that, in this work, the crystallization and initial X-ray diffraction characterization of DhaA wild type and its mutant variant DhaA13 in complex with environmental pollutant 1,2,3-trichloropropane and the crystallization of DhaA13 in complex with the fluorescence dye coumarin are described.

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2017-04-07T13:57:20Z No. of bitstreams: 1 texto completo.pdf: 2824180 bytes, checksum: 35078d63ffeaef3e4935030bf53dc74e (MD5) / Made available in DSpace on 2017-04-07T13:57:20Z (GMT). No. of bitstreams: 1 texto completo.pdf: 2824180 bytes, checksum: 35078d63ffeaef3e4935030bf53dc74e (MD5) Previous issue date: 2016-08-18 / Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Esse estudo é iniciado com uma revisão bibliográfica em que aborda a biorremediação de hidrocarbonetos pesados e hidrocarbonetos aromáticos policíclicos (PAHs). Na revisão, são explorados aspectos que incluem a obtenção de micro- organismos com capacidade de degradar hidrocarbonetos, vias metabólicas de biodegradação, as consequências ambientais da contaminação e por fim aborda novos estudos que utilizam estratégias e novas tecnologias de biorremediação possíveis em ambientes aquáticos e solos. A parte experimental de nosso estudo segue a mesma linha de pesquisa desenvolvida durante o mestrado. De maneira preventiva, busca-se avaliar e desenvolver metodologias para biorremediar as adjacências da Ilha da Trindade, ambiente pristino e de valor ecológico, caso ocorram acidentes envolvendo o derramamento de hidrocarbonetos. Inicialmente, objetivamos avaliar o genoma dos isolados bacterianos autóctones da comunidade microbiana existente nas águas marinhas que circundam a Ilha da Trindade, Rhodococcus rhodochrous TRN7 e Nocardia farcinica TRH1, isolados durante o trabalho de mestrado como sendo capazes de degradar uma grande variedade de hidrocarbonetos de petróleo. Nosso objetivo também foi avaliar a estrutura da comunidade microbiana e o catabolismo de fenantreno após contaminação de microcosmos contendo água coletada na mesma região e utilizar micro-organismos autóctones como estratégia de bioaumentação. Por fim, objetivou-se desenvolver um produto biotecnológico baseado em emulsões duplas W/O/W fertilizadas, capaz de promover a bioestimulação sem a perda instantânea de nutrientes em águas oceânicas oligotróficas contaminadas por compostos orgânicos hidrofóbicos. Os genomas de R. rhodochrous TRN7 e N. farcinica TRH1 possuem genes de degradação de compostos alifáticos e aromáticos, sendo que 17 genes envolvidos com a biossíntese de antibióticos foram anotados com o genoma de R. rhodochrous TRN7, enquanto que no genoma de N. farcinica TRH1 foram identificados genes relacionados à degradação de caprolactam, precurssor do nylon, e do pesticida atrazina, o que torna ambos os isolados candidatos a serem empregados tanto em estratégias de bioaumentação quanto em outras áreas biotecnológicas. Após a contaminação de microcosmos com hidrocarbonetos, a comunidade microbiana da água litorânea da Ilha da Trindade passa a ser dominada por Gammaproteobacteria, grupo que compõe mais de 72% das sequências analisadas, enquanto que no tratamento controle houve predomínio de Proteobacteria (95% das sequências). Destaca-se a abundância de representantes do gênero Alteromonas, presentes em todos os tratamentos contaminados, com maior valor de abundância (66% das sequências) no tratamento contendo apenas fenantreno como contaminante. Decorridos 30 dias da contaminação, os valores de diversidade foram reduzidos, havendo domínio de grupos bacterianos reconhecidos pela presença de membros com atividade hidrocarbonoclástica. A capacidade de mineralização de fenantreno pela microbiota autóctone da Ilha da Trindade é reduzida quando outros PAHs e hidrocarbonetos de alto peso molecular estão presentes no ambiente. Em relação às emulsões produzidas, nossos resultados mostraram que elas podem ser utilizadas com o propósito de liberação gradual de nutrientes na fase aquosa dispersa. A emulsão é composta por gotículas que variam em um amplo espectro de tamanho que se desestabilizam temporalmente, resultando na liberação da inorgânicos. Quando utilizadas em hidrocarbonoclásticas, fase aquosa conjunto em microcosmos interna, ou contendo não, água contendo nutrientes com bactérias litorânea da Ilha da Trindade contaminada com petróleo, as emulsões W/O/W fertilizadas proporcionaram aumentos significativos da atividade microbiana. Como conclusões, nosso trabalho mostrou que a contaminação por hidrocarbonetos resulta na perda de diversidade microbiana da comunidade microbiana da água litorânea da Ilha da Trindade, e que um ambiente considerado pristino possui microbiota capaz de degradar hidrocarbonetos. Por fim, conclui-se que emulsões duplas W/O/W fertilizadas são uma alternativa para proporcionar aumento significativo na atividade catabólica de hidrocarbonetos em ambientes marinhos oligotróficos. / This study starts with a literature review approach in heavy hydrocarbon bioremediation and polycyclic aromatic hydrocarbons (PAHs). In the review are explored aspects from obtaining microorganisms capable of degrading hydrocarbons, metabolic biodegradation pathways, environmental consequences of contamination and finally discusses new studies using new strategies and bioremediation technologies in water and soil environments. The experimental part of our study follows the same research line developed during the Masters. Preventively, seeks to assess and develop bioremediation methodologies for Trindade Island shoreline, pristine environment with ecological value, should they occur involving the oil spill. Initially we aimed to evaluate the genome of indigenous bacterial isolates Rhodococcus rhodochrous TRN7 and Nocardia farcinica TRH1, isolated during master’s work as being capable of degrading a wide range of petroleum hydrocarbons. Our aim was also to evaluate the microbial community structure and metabolism of PAHs after contamination in microcosms and use indigenous microorganisms as bioaugmentation strategy. Finally, it aimed to develop a biotechnolocal product based on double emulsion W/O/W fertilized able to promote biostimulation without the instant loss of nutrients in oligotrophic oceanic waters contaminated with hydrophobic organic compounds. The genomes of R. rhodochrous TRN7 and N. farcinica TRH1 presents aliphatic and aromatic compounds degradation genes. Moreover, 17 genes involved in the biosynthesis of antibiotics were recorded in the genome of R. rhodochrous TRN7 while in the genome of N. farcinica TRH1 were identified genes related to the degradation of caprolactam, a nylon precursor, and the pesticide atrazine, which makes the isolates candidates to be used in both strategies bioaugmentation as for other biotechnological activity. After contamination by hydrocarbons, in microcosms, the microbial community of the coastal water from Trindade Island becomes dominated by Gammaproteobacteria, a group that makes up more than 72% of the analyzed sequences, while in the control treatment predominated Proteobacteria (95% of the sequences). Noteworthy is the abundance of representatives of the genus Alteromonas, present in all the contaminated treatments with highest abundance (66% of the sequences) in the treatment containing phenanthrene as only contaminant. After 30 days of contamination, diversity values were reduced, with domain of bacterial groups recognized by the presence of members with hydrocarbonoclastic activity. The phenanthrene mineralization capacity by the indigenous microbiota of the Trindade Island is reduced when other PAHs and high molecular weight hydrocarbons are present in the environment, however, does not cease to occur. With respect to emulsions produced, our results showed that they can be used for the purpose of slow release nutrients in the dispersed aqueous phase. The emulsion comprises droplets ranging in a wide range of size that destabilize temporally, resulting in the release of the internal aqueous phase, containing inorganic nutrients. When used together or not, hydrocarbonoclastic bacteria in microcosms containing coastal water from Trindade Island contaminated with oil, the fertilized W/O/W emulsion provided significant increases in microbial activity. In conclusion, our work has shown that hydrocarbons contamination results in the loss of microbial diversity in marine environments, in addition to state that as environment considered pristine has microbiota capable of degrading hydrocarbons and therefore it becomes viable the use of strategies as biostimulation and bioaugmentation employing indigenous bacterial isolates previously selected. Finally, it is concluded that fertilized W/O/W emulsions are an alternative to provide significant increase in catabolic activity hydrocarbons oligotrophic marine environments.

[pt] A crescente demanda mundial por matérias-primas minerais levou ao aumento da exploração mineral e paralelamente novas pesquisas estão sendo dirigidas para a produção de novos reagentes de flotação, a fim de que estes apresentem maior seletividade e não sejam agressivos ao meio ambiente. Nesta pesquisa teve-se como objetivo estudar os aspectos fundamentais da bioflotação da hematita, avaliando a cepa bacteriana Rhodococcus erythropolis como biocoletor. Entre os estudos efetuados estão análises química para determinar as proteínas e carboidratos presentes no concentrado bacteriano, estabelecendo-se que é constituída por macromoléculas com características anfipáticas. O balanço entre grupos catiônicos e aniônicos da bactéria atribui um ponto isoelétrico (PIE) equivalente de 2,2. O perfil de potencial zeta da amostra mineral de hematita após interação com a bactéria mostrou uma mudança, onde o PIE mudou de 5,3 para 2,1. Para o estudo dos ensaios de adesão e microflotação, a amostra foi condicionada com a biomassa por meio de agitação sob condições específicas, tais como os tamanho de partícula, a concentração de biomassa, o pH da solução e tempo de condicionamento. A adesão da biomassa na superfície do mineral foi maior em pH 2 e na concentração de 200 mg / L. Os testes de microflotação foram feitos num tubo de Hallimond e foi avaliado a formação de espuma para uma concentração bacteriana de 200 mg / L, onde foi observado que a tensão superficial da solução aumenta à medida que o pH se torna básico. Das três faixas granulométricas utilizadas, a maior flotabilidade (83.86 por cento) foi alcançada na fração granulométrica (53 - 38 um), num pH 6 e com um tempo de flotação de 10 min. A bioflotação do mineral hematita segue o modelo cinético de segunda ordem, observou-se que as constantes de taxa (K2) da flotação do mineral aumentam com reduções de tamanho de partícula, mudando de 0,16369 (g.min)(-1) para 0,51604 (g.min)(-1) quando o tamanho de particula passou de (150 - 106 um) para (53 - 38 um). Os resultados apresentados mostram que o estudo do comportamento da cepa bacteriana Rhodococcus erythropolis como bioreagente na flotação de hematita foi viável, demonstrando o seu potencial uso como bioreagente coletor de mineral hematita, e assim projetando-se para uma futura aplicação na indústria da flotação mineral. / [en] The growing world demand for raw minerals has led to the increased mineral exploration and at the same time new research is being directed toward the production of new flotation reagents, so that they present higher selectivity and they are environmentally friendly. This research aimed to study the fundamental aspects of bioflotation of hematite, evaluating the bacterial strain Rhodococcus erythropolis as biocollector. Among the studies are conducted chemical analyzes to determine the proteins and carbohydrates present in the bacterial concentrate, it was established that is composed of macromolecules with amphipathic characteristics. The balance between cationic and anionic groups of the bacteria assigns an equivalent isoelectric point (IEP) of 2.2. The profile of zeta potential of the sample of hematite mineral after interaction with the bacteria showed a change, where the IEP has changed from 5.3 to 2.1. To study the adhesion and microflotation assays, the mineral sample was conditioned with the biomass by stirring under specific conditions, such as the particle sizes, biomass concentration, the pH of the solution and conditioning time. The biomass adhesion on mineral surface was higher at pH 2 and at the concentration of 200 mg / L. The microflotation tests were carried out in Hallimond tube and was evaluated the foam formation to a bacterial concentration of 200 mg / L, which was observed that the surface tension of the solution increases as the pH becomes basic. Of the three granulometric fractions used, the greatest floatability (83.86 percent) was achieved in the granulometric fraction (53 - 38 um), at pH 6 and with a flotation time of 10 min. The hematite mineral bioflotation follows the second-order kinetic model, was observed rate constant (K2) of the mineral flotation increase with reductions of particle size, moving from 0,16369 (g.min)(-1) for 0,51604 (g.min)(-1) when the particle size changed from (150 - 106 um) to (53 - 38 um). The results presented show that the study of the behavior of the bacterial 10 strain Rhodococcus erythropolis as bioreagent in the flotation of hematite was feasible, demonstrating its potential use as collector bioreagent of mineral hematite, and so projecting into a future application in the mineral flotation industry.