[pt] A bioflotação é definida como um processo de separação, através do qual o mineral de interesse é flotado ou deprimido seletivamente, utilizando os reagentes de origem biológica, também conhecidos como bioreagentes. Estas substâncias são caracterizadas por possuírem uma química verde, seletividade e potencial para tratar a partículas finas. Neste sentido, o objetivo principal da pesquisa é a avaliação de um biosurfactante não refinado extraído da bactéria Rhodococcus opacus na flotação de hematita. Na primeira fase, foi desenvolvido um protocolo para a extração dos biosurfactantes intracelulares e aqueles associados a parede celular da bactéria. Mediante extração com etanol a 121 graus celsius e 2 atm, as substâncias anfifílicas foram liberadas e solubilizadas. A recuperação média de biosurfactante não refinado foi de 0,3 g por dm cubico. A caracterização por FTIR identificou grupos álcool (menos OH), cetona (C igual O) e cadeias de carbono saturadas e insaturadas. Que podem compor os mycolatas e trehalolipideos que são encontrados na parede celular da bacteria. Por estudos eletroforéticos encontrou-se umPIE de 7,5 e um PZC em torno de 7,6. Aplicando o modelo Gouy-Chapman e o modelo misto de Gouy Chapman e o capacitor de placas, foi possível estudar o efeito do biosurfactante no comportamento eletrostático das partículas de hematita. Predizendo como elas foram se tornando hidrofóbicas em valores de pH ácido e como sua flotabilidade diminuía em pH básicos, após interação com o biosurfactante. Finalmente, foi testado o biosurfactante e a própria bactéria em ensaios de microflotação de hematita, resultando o primeiro na melhora na flotabilidade de hematita. Os resultados mostraram uma boa afinidade e baixo consumo de reagente. / [en] Bioflotation is defined as a separation process by which the mineral of interest is floated or depressed selectively, using reagents of biologic origin also known as bioreagents. These substances are characterized by their green chemistry, selectivity and potential to treat fine particles. Currently they are been studied with the expectative of substitute the synthetic reagents used in the mineral flotation processes. Between the diverse microorganisms, the hydrophobic bacteria Rhodococcus opacus has been studied as biofrother and biocollector in hematite flotation. In that sense, the research s principal objective is the assessment of the hematite floatability using a crude biosurfactant extracted from the bacteria Rhodococcus opacus and consequently determine its potential as an alternative against synthetic reagents or the bacteria itself. In a first stage, it was developed a protocol for the extraction of cell associated and intracellular biosurfactants from the bacteria. Throughout ethanol extraction at 121 degrees centigrade and 2 atm, the cell associated substances where released and solubilized. The average crude biosurfactant recovery was around 0.3 g per L of broth. Characterization by FTIR identified alcohol (minus OH) and ketone (C equal O) groups as well as saturated and unsaturated carbon chains. Which may compose the mycolates and trehalolopids that are found in the cellular wall of the genera Rhodococci. Electrophoretic studies of the hematite sample, before BS interaction, found an IEP around a pH of 7.5 and a PZC at pH 7.6. Applying the Guoy-Chapman model and the mixed model of Guoy Chapman and the plate capacitor, it was possible to study the effect of the biosurfactant onto the electrostatic behavior of the hematite particles. The model predicted the hydrophobicity of the modified hematite at acid pH. Finally it was tested the crude biosurfactant against the bacteria itself in microflotation tests, resulting the first one in an improved hematite floatability. The results showed a high affinity of the crude biosurfactant for hematite particles and relatively low reagent consumption.

[pt] Nos últimos anos, vários estudos têm sido realizados na aplicação dos microrganismos na biotecnologia mineral, atuando como coletores, depressores ou espumantes amigáveis com o meio ambiente, e induzindo propriedades hidrofóbicas, uma vez que eles podem-se aderir seletivamente sobre a superfície do mineral. O objetivo deste trabalho é estudar e avaliar o comportamento da cepa Rhodococcus ruber com a hematita. Entre os estudos efetuados estão à adesão microbiana à superfície mineral, medida do potencial zeta e análise no infravermelho antes a após interação do biorreagente com a hematita, assim como o estudo dos ensaios de microflotação. A amostra foi condicionada com a suspensão de biomassa por meio de agitação sob condições específicas, tais como tamanho das partículas, concentração da biomassa, pH da solução e tempo de condicionamento. Os resultados mostraram uma mudança no perfil do potencial zeta da hematita após interação com a R.ruber, e sua adesão na superfície do mineral foi maior ao redor do pH 3, e na concentração de 0.60g.L(-1) (10(9) células). Estudos de flotação foram realizados na célula de flotação modificada Partridge-Smith de 0.23L, e a maior valor de flotabilidade (84 por cento) foi atingido na fração menos 53 mais 38 um. Estudos complementários de flotabilidade foram realizados utilizando o espumante comercial Flotanol D24 combinado com a biomassa R.ruber, encontrando resultados interessantes em função do tamanho de partícula. Assim esta pesquisa visa avaliar a eficiência da bioflotação de minerais, particularmente da hematita, e do uso potencial do Rhodococcus ruber como biocoletor, projetando-se a uma futura aplicação na indústria da flotação mineral. / [en] In the recent years, research has been developed in the application of microorganisms in mineral technology, acting as environmental friendly collectors, depressors and/or frothers and inducing hydrophobic properties, since they can be selectively adhere onto the surface of the mineral. This research work deals with the fundamental aspects of hematite flotation using the bacterial strain Rhodococcus ruber. The aim of this research was to study and evaluate the behavior of Rhodococcus ruber strain before and after interaction with hematite particles. The sample was conditioned with the biomass suspension by stirring under specific conditions such as particle size, biomass concentration, pH solution and conditioning time. Among the studies conducted are the microbial adhesion to the mineral surface, zeta potential measurements and analysis of infrared spectra before and after interaction of Rhodococcus ruber with hematite, as well as microflotation studies. The results showed a change in hematite zeta potential profile after interaction with Rhodococcus ruber, and its adhesion onto the mineral surface was higher at pH 3 and at concentration of 0.60 g.L(-1) (10(9) cells). Flotation studies were carried out in a 0.23L modified Partridge-Smith flotation cell, and the highest floatability (84 percent) was achieved at size fraction any less 53 more 38 um. Also, floatability studies were performed using frother Flotanol D24 combined with the Rhodococcus ruber biomass, concluding with interesting results in function of the particle size range. This work aims to evaluate the efficiency of bioflotation of minerals, particularly hematite, and the potential use of Rhodococcus ruber as biocollector, projecting its future application in mineral flotation industry.

Les pathosystèmes, plante-bactérie, aboutissent souvent au niveau de la plante à de profondes reprogrammations tant au niveau de la morphogenèse que du métabolome. Dans le cas de l’interaction plante-Rhodococcus fascians, une bactérie phytopathogène, il se développe au niveau du site d’infection, une structure morphologique particulière nommée « galle feuillée ». <p>Au sein de cette hyperplasie, les altérations métaboliques induites concernent non seulement les produits du métabolisme primaire mais également le métabolisme secondaire et plus particulièrement des composés qui interviennent dans les mécanismes de défense ou qui affectent la prolifération cellulaire végétale. <p>Dans le cadre de notre travail de thèse, nous nous sommes fixé deux objectifs principaux qui sont de caractériser les altérations métaboliques au niveau des tissus hyperplasiques de tabac mais aussi de rechercher des applications potentielles du point de vue thérapeutique de cette interaction.<p>L’approche métabolomique globale basée sur une analyse comparative des spectres 1H-RMN d’extraits bruts de tissus infectés et de tissus non-infectés couplée à des analyses statistiques de données multivariées (ACP, OPLS-DA) a été utilisé pour l’étude de la reprogrammation métabolique. Le résultat indique une accumulation de composés phénoliques et des métabolites de la famille des diterpènes dans les tissus de la galle feuillée. <p>Les activités biologiques des extraits de la galle feuillée ont ensuite été évaluées, notamment des activités antioxydantes (DPPH, FRAP), anti-inflammatoire (15-LOX) et antiproliférative (MTT). Il ressort de cette analyse une augmentation du potentiel réducteur et anti-radicalaire des extraits de la galle feuillée, une activité inhibitrice de la lipoxygénase ainsi qu'une activité antiproliférative sur lignées tumorales humaines, comparée à la plante non infectée. <p>L’étude des composés affectant la prolifération des cellules cancéreuses humaines a aboutit à la mise en évidence d’un mélange de molécules (F3.1.1) appartenant au groupe des incensoles (cembrènoïdes). Ces composés ralentissent la durée de la division cellulaire, affectent la taille des cellules et induisent des anomalies de la karyokinèse et de la cytokinèse des cellules de glioblastome U373. La dynamique tubuline/microtubule est identifiée comme étant la cible des cembrènoïdes (F3.1.1). L’effet des ces composés est original comparé aux anti-tubulines usuels tel que la colchicine et le paclitaxel. Le mécanisme d’action des incensoles est unique et donc prometteur du fait que la dynamique des microtubules reste une cible de choix dans le traitement des cellules cancéreuses.<p> / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished

[pt] Neste estudo foi avaliada a capacidade de adsorção do poluente orgânico tolueno em contato com a cepa Rhodococcus opacus. O tolueno foi selecionando por fazer parte do grupo de compostos BTEX (Benzeno, Tolueno, Etilbenzeno e Xileno), que possui elevada toxicidade, causando impacto ambiental em corpos hídricos, solo e ar, além de possuir características mutagênica e carcinogênica em humanos. A determinação e quantificação do tolueno na solução aquosa foram realizadas em um cromatógrafo a gás, acoplado ao espectrômetro de massas com amostrador automático headspace. A cepa Rhodococcus opacus foi caracterizada por análise de espectrometria no infravermelho e medição de potencial zeta, sendo a última realizada antes e após o contato com o tolueno. Os modelos de isotermas lineares de Langmuir, Freundlich e Temkin foram aplicados aos dados experimentais para descrever o processo de adsorção. Tendo o modelo de Langmuir se adaptado melhor ao processo em análise. As variáveis estudadas para otimizar as condições máximas de adsorção foram: tempo de contato, variação do pH, variação da biomassa. Este estudo mostrou que a cepa bacteriana R. opacus apresentou uma boa capacidade de biossorção, principalmente para concentrações baixas, onde removeu 95,99 porcento e 85,69 porcento das respectivas concentrações de 0,6 e 0,8 mg/L de tolueno, atendendo a resolução do CONAMA 357/2005 para águas salobras de Classe I. / [en] In this study was evaluated the adsorption capacity of the organic pollutant toluene by the Rhodococcus opacus strain. Toluene was chosen by being part of the group of BTEX compounds (benzene, toluene, ethylbenzene and xylene), which has high toxicity, causing environmental impact on water bodies, soil and air, and also are mutagenic and carcinogenic to humans. The determination and quantification of toluene in aqueous solution were performed on a gas chromatograph, coupled with a mass spectrometer with headspace autosampler. The strain Rhodococcus opacus was characterized by infrared spectrometry analysis and zeta potential measurement, the last done before and after the sorption. The isotherm linear models of Langmuir, Freundlich and Temkin were applied to the experimental data to describe the adsorption process. Having the Langmuir model better adapted to process analysed. The variables studied to optimize the maximum adsorption conditions were: contact time, pH variation, biomass variation. This study showed that the bacterial strain R. opacus has good biosorption capabilities, particularly at low concentrations, where it removed 95.99 percent and 85.69 percent of the respective concentrations of 0.6 and 0.8 mg/L of toluene, attending the CONAMA resolution 357/2005 for salt waters of Class I.

[pt] Neste trabalho foi avaliado o potencial do microorganismo R. opacus como biossorvente para a remoção de Pb(II), Cr (III) e Cu(II) de soluções aquosas pelo processo de biossorção/bioflotação, através de ensaios experimentais em batelada. Os parâmetros operacionais investigados na etapa de biossorção foram: o pH da solução, a concentração de biomassa, o tempo de contato e a concentração inicial do metal. Na separação da biomassa carregada mediante a bioflotação por ar disperso se avaliou o tempo de flotação, e as características da espuma. As características da superfície do micro-organismo e os possíveis mecanismos de interação envolvidos na sorção dos metais tóxicos por R. opacus, foram avaliadas com base em medições de potencial zeta, análise por espectrometria no infravermelho e análise de micrografias obtidas no microscópio eletrônico de varredura (MEV). O valor inicial do pH da solução afetou a sorção dos metais, os valores de pH adequados na etapa de sorção e na flotação foram de 5,0 para o Pb(II) e pH igual a 6,0 para o Cr(III) e Cu(II). Os ensaios da cinética de biossorção mostraram que o processo é rápido e em 60 minutos de contato entre a biomassa e a solução de metal foi atingida a máxima captação das espécies metálicas em estudo. Os dados correspondentes à capacidade de captação do R. opacus em função da concentração dos íons metálicos foram bem ajustados ao modelo da isoterma de Langmuir para as três espécies em estudo, onde as capacidades máximas de captação obtidas foram: 94,3; 72,9 e 32,2 mg.g-1 para Pb(II), Cr(III) e Cu(II), respectivamente. A cinética da sorção para o Pb(II), Cr(III) e Cu(II) foram modeladas usando a equação de pseudo segunda ordem. A ordem de afinidade do R. opacus obtida em sistemas individuais foi estabelecida como: Pb(II) >Cr(III)>Cu(II). Essa diferença na afinidade do R. opacus pode ser atribuída às propriedades físico-químicas destes metais, dentre elas peso atômico, raio iônico e eletronegatividade. A capacidade de captação dos íons Pb (II) pela biomassa foi reduzida pela presença de outras espécies metálicas no sistema, apresentando o Cr(III) maior afinidade pelos sítios da biomassa do que os outros íons. Na bioflotação, verificou-se que o micro-organismo apresenta resultados muito promissores como coletor e espumante, obtendo-se percentagens de remoção de Pb(II), Cr(III) e Cu(II) de 94%, 54% e 43% , respectivamente, partindo de uma concentração de 20 mg.l-1. Os resultados apresentados mostram que R. opacus apresenta características adequadas no que tange a biossorção e bioflotação para a remoção de metais pesados. / [en] This work evaluated the potential of the Rhodococcus opacus strain as a biosorbent for the removal of Pb(II), Cr(III) and Cu(II) from aqueous solutions by Biosorption/bioflotation process, through experimental batch tests. The operational parameters investigated in the biosorption´s stage were: pH of the solution, biomass concentration, contact time and initial metal concentration. In the separation of the loaded biomass by bioflotation process for dispersed air were evaluated the flotation time and the foam characteristics. The characteristics of the microorganism surface and the involved interaction mechanisms in the heavy metals sorption by R. opacus, were evaluated based in the potential zeta measurements, infrared spectroscopy and electron microscopy scanning analysis. The solution initial pH value affected metals sorption, the adjusted pH values in the sorption and the flotation stage were 5.0 for the Pb(II) and pH value of 6.0 for the Cr(III) and Cu(II). The experiments of biosorption kinetics showed that the process is relatively fast and in sixty minutes of contact between the biomass and the metal solution were reached the maximum metal uptake capacities. The data pertaining to the uptake capacity of the R. opacus in function of the metal ion concentration fitted to the Langmuir isotherm model for the tree species in study, where the maximum uptake capacities obtained were: 94.3; 72.9 and 32.2 mg.g-1 for Pb (II), Cr(III) and Cu(II), respectively. The kinetics of sorption of Pb(II), Cr(III) and Cu(II) were modeled using a pseudo second order rate equation. The affinity order of R. opacus for the three metals under study has been established as: Pb(II)>Cr(III)>Cu(II). The selectivity of the biomass for the Pb(II) over the other two metals was well exhibited by the results obtained in the biosorption and bioflotation. This difference in the affinity of the R. opacus can be attributed to the physiochemical properties of these metals, amongst them atomic weight, ionic radio and electronegativity. The uptake capacity of ions Pb(II) for the biomass was reduced by the presence of other metallic species in the system, and the results showed that the Cr(III) has greater affinity for the biomass than the others ions. In the bioflotation, it was found that the microorganism presents excellent characteristics as collector and foaming agent, reaching 94%, 54% and 43% removal of lead, chromium and copper, respectively, to 20 mg.l-1 of concentration. The results of this study showed that R. opacus has important features for the heavy metal removal; moreover, the results also showed that R. opacus is especially effective biosorbent for the removal of Pb(II).

Das Bodenbakterium Rhodococcus opacus 1CP ist für sein Potenzial bekannt, organische Schadstoffe abzubauen. In dieser Studie lag der Fokus auf zwei Genprodukten, den farbstoffabbauenden Peroxidasen DypA und DypB, welche unter Anwendung von Klonierungs- und Expressionsstrategien mit hohen spezifischen Aktivitäten in reiner Form gewonnen werden konnten. Eine umfassende biochemische Analyse zeigte, dass beide Enzyme in der Lage sind, Farbstoffe unterschiedlicher Klassen, insbesondere jedoch, die als schwer abbaubar geltenden Anthraquinone, strukturell anzugreifen. Damit stellen sie lohnenswerte enzymatische Systeme zum Abbau toxischer Farbstoffe beispielsweise in industriellen Abwässern dar.

Rhodococcus rhodochrous DAP 96253, a well-known industrial bacterium, had various 1-hexene monooxygenase (1-HMO) activities when grown on YEMEA plates supplemented with eight different carbohydrates. Besides, 1-HMO exhibited different storage temperature preferences. Lactose could induce the highest 1-HMO activity in R. rhodochrous DAP 96253 while the cells showed the lowest 1-HMO activity when trehalose was the supplement. The 1-HMO activity of R. rhodochrous DAP 96253 was not maintained when stored at 37°C as well as at 4°C and 25°C. Trehalose-induced 1-HMO activity of R. rhodochrous DAP 96253 was more stable from Day 0 to Day 21 at all these three temperatures, compared with the other seven carbohydrates. Immobilization of enzymes can maintain enzyme activity longer, offer easier enzyme storage conditions and make some enzymes reusable, much research has been done in this area. In this study, R. rhodochrous DAP 96253, grown on YEMEA plates supplemented by glucose and urea, was investigated using whole bananas as the inducer of 1-HMO activity and different immobilization methods to maintain this enzyme activity. It was shown that calcium-alginate polyvinyl alcohol (PVA) beads could maintain 1-HMO activity of R. rhodochrous DAP 96253 more stable than calcium-alginate beads. Whole bananas exhibited very obvious effects of inducing 1-HMO activity of R. rhodochrous DAP 96253. A number of recent studies have clearly demonstrated that induced cells of R. rhodochrous DAP 96253 can prolong the shelf-life of post-harvested fruits. With USDA estimates of 40% of all harvested produce in the US not being consumed because of loss of quality, the ability to extend the period of ripeness of produce has great potential to improve the quality of nutrition. Modification or degradation of those signals (primary and secondary) associated with ripening in fruit or the perception of those signals represents a potential mode of action for delayed ripening by induced cells of R. rhodochrous DAP 96253. Ethylene and cyanide are the two primary signals in ripening. In this study, the role of 1-HMO from induced cells was investigated by time-course experiments focusing on 1-HMO activity and stability. In addition, fruit volatile organic compounds (VOCs) were detected and compared by GC-FID and GC/MS over the course of fruit ripening. The results show a correlation between 1-HMO activity and stability in delayed fruit ripening. It was further demonstrated that the presence of secondary signal fruit VOCs enhanced 1-HMO activity. Aromatic profiles of treated fruits, by GC-FID and GC/MS, show a consistent picture of VOCs associated with earlier fruit ripening stages.

Rhodococcus rhodochrous is an aerobic, non- pathogenic ,gram-positive bacterium that is often used in industries as a biocatalyst.R. rhodochrous DAP 96253 is capable of exhibiting contact-independent inhibition of selected fungal pathogens.The use of R. rhodochrous as a potential biocontrol agent against plant and animal fungi was examined.The fungi tested were Botrytis cinerea,Pseudogymnoascus destructans,Aspergillus flavus, Fusarium oxysporum’Cigar Tip’ , Rhizopus stolonifer’D1’ ,and other species isolated from berries.Each species was studied to establish the effect of dose (g/cells) and time of exposure to R. rhodochrous.Antifungal inhibition tests were done with the use of dosing,agar diffusion, frozen fermentation paste and exposed slides.Inhibition was observed with B.cinerea,P.destructans,A.flavus and D1,and reduced sporulation was observed with Cigar Tip. The results varied amongst the type of tests used on each target species.

Rhodococcus equi is a soil-dwelling facultative intracellular pathogen that can infect many mammals, including humans. R. equi is most well known for its ability to cause severe pyogranulomatous disease in foals, primarily involving the lungs although other body systems may also be affected. The disease is endemic on many horse-breeding farms worldwide and poses a severe threat to the horse breeding industry because there is no vaccine available. Current prophylaxis is based on systematic preventative treatments with macrolides combined with rifampicin, which are also used to treat clinical cases of the disease in foals. In this thesis I have used a combination of wet laboratory and bioinformatic approaches to identify the molecular basis of emerging combined resistance to macrolides and rifampicin in R. equi foal isolates from the USA. The genomes of a selection of resistant and susceptible strains from across the USA were sequenced and assembled. Resistance genes were systematically searched by reciprocal best-match BLASTP comparisons to known antibiotic resistance determinants. This led to the discovery of a novel erythromycin ribosomal methylase (erm) gene, erm(46), in all resistant strains. Complementation analysis in a susceptible R. equi strain showed that erm(46) was sufficient to confer resistance to all macrolides, lincosamides, and streptogramin B. The erm(46) gene is carried by an integrative conjugative element (ICE) which is transferable between R. equi strains. The ICE is formed by two distinct parts, a class I integron associated with an IS6100 sequence and the erm(46) determinant carried by a sub-element which contains putative actinobacterial conjugative translocase apparatus and a transposase/integrase. All resistant strains also carry the same non synonymous point mutation in rpoB conferring rifampicin resistance. Thus, these strains are carrying double resistance to the most commonly used antibiotics to treat R. equi worldwide. Phylogenetic analysis based on the core genome demonstrated that all resistant strains are clonal. This indicates that although conjugal acquisition of the erm(46) conjugative element may occur at a high frequency, the need for the concurrent presence of a second rpoB mutation for survival in the macrolide and rifampicin dominated farm environment has effectively selected for the spread of a single clone. In the second section of this work, we sequenced a further 20 R. equi genomes from difference sources (equine, porcine, bovine, human), including representatives of each of the seven major genogroups previously defined in our laboratory based on pulsed field gel electrophoresis. I have used the newly acquired genetic information to study the genome of R. equi and analyse its diversity within and outwith its species group. This enabled us to explore the pan genome and define that R. equi is a genetically well-defined bacterial species. Our results provide definitive evidence that resolves the current dispute over R. equi classification, specifically they do not support the recent proposal (based on classical polyphasic bacterial taxonomical methods) that R. equi should be transferred to a new genus. Our core-genome phylogenomic analyses unambiguously show that the genus Rhodocococcus is monophyletic and that R. equi forms a clade together with the most recently described related environmental species R. defluvii that radiates from within the genus. Together with other shared biological and genetic characteristics, namely the unique niche-adaptive mechanism based on evolutionarily related extrachromosomal replicons, R. equi should be conseidered a bona fide member of the genus Rhodococcus. We also confirm that Rhodococcus spp. and Nocardia spp. are sufficiently distinct to warrant them belonging to different genera. In conclusion, this work used whole genome sequencing to characterize the molecular basis underlying the emergence and clonal spread of multi-resistant R. equi in horse breeding farms in the USA. This work also highlights the limitations of classical taxonomical approaches in bacterial systematics, and illustrates the importance of incorporating modern phylogenomic approaches to understand the evolutionary relationships between bacterial strains and their accurate taxonomic position.

Orientador: Márcio Garcia Ribeiro / Banca: Antonio Carlos Paes / Banca: José Paes de Almeida Nogueira Pinto / Banca: Adolfo Carlos Barreto Santos / Banca: Rogério Giuffrida / Resumo: A linfadenite infecciosa em suínos representa uma das afecções mais preocupantes na criação de suínos em todo mundo, causada por patógenos de origem bacteriana, geralmente diagnosticada na linha de abate. Acarreta prejuízos econômicos com a condenação total ou parcial das carcaças, bem como reflexos em saúde pública, devido ao potencial zoonótico dos agentes causais. O presente estudo investigou a ocorrência e as principais espécies do gênero Mycobacterium, assim como marcadores de virulência plasmidial em linhagens de Rhodococcus equi (R. equi) isoladas de linfonodos e das fezes de suínos de abatedouros do interior do estado de São Paulo, com e sem linfadenite. Foram examinados 150 linfonodos (50 mesentéricos, 50 mediastínicos e 50 submandibulares) com lesões, 150linfonodos (50 mesentéricos, 50 mediastínicos e 50 submandibulares) sem lesões aparentes e 150 fezes de suínos, provenientes de animais destinados ao abate, em dois frigoríficos do interior do estado de São Paulo. As amostras de linfonodos e fezes foram submetidas ao cultivo microbiológico simultaneamente nos meios de ágar acrescido de sangue bovino (5%) desfibrinado, e meios seletivos de CAZ-NB, TCP e TVP para R. equi, e Stonebrink-Lesslie e Lowenstein-Jensen para micobactérias. As colônias sugestivas de R. equi e positivas no teste de CAMP, foram enviadas ao Japão para detecção de linhagens VapA ou VapB, associadas a virulência. As linhagens sugestivas no cultivo microbiano para o gênero Mycobacterium foram submetidas a caracterização de espécies por PCR pela técnica de PRA. Foram identificados nos linfonodos de suínos com lesões 48 (32,0%) linhagens de Mycobacterium spp.e 6 (4,0%) Rhodococcus equi. Nos linfonodos de suínos sem lesões foram identificados 11 (7,3%) isolados de Mycobacterium spp.e nenhuma linhagem de R. equi. Nas fezes foram identificadas 40 (26,6%) linhagens de Rhodococcus equi e ... / Abstract: The infectious lymphadenitis represents one of the most important diseases in pigs worldwide caused by bacterium, usually diagnosed on the slaughterhouses.The disease leads to economic losses due to total or partial condemnation of carcasses, as well as public health concern due to the zoonotic potential of microorganisms. The present study investigated the occurrence and the main species of the genus Mycobacterium as well as virulence markers of plasmid in Rhodococcus equi (R. equi) strains isolated from lymph nodes and feces from pigs of slaughterhouses in the state of São Paulo, with and without lymphadenitis. Were sampled 150 lymph nodes (50 mesenteric, 50 mediastinal and 50 submandibular) with lesions, 150 lymph nodes (50 mesenteric, 50 mediastinal and 50 submandibular) without visible lesions, and 150 feces from pigs of slaughterhouses of state of São Paulo, Brazil. The lymph nodes samples and feces were subjected to microbiological culture simultaneously indefibrinated bovine blood agar (5%), selective media of CAZ-NB, TCP, TVP for R. equi, and Stonebrink-Lesslie, and Lowenstein-Jensen for mycobacteria . The suggestive colonies of R. equi and positive to CAMP test were sent to Japan for evaluation of plasmid profile (VapA or VapB). The suggestive of Mycobacterium sp. were subjected to polymerase chain reaction (PCR) - based species identification using restriction enzyme pattern analysis (PRA). Among lymph nodes of pigs with lesions, 48 (32.0%) Mycobacterium spp. and 6 (4.0%) R. equi strains were identified. In the lymph nodes of pigs without lesions were identified 11 (7.3%) Mycobacterium spp. and none R. equi strain. From the fecal samples, 40 (26.6%) R. equi and 2 (1.3%) Mycobacterium spp. isolates were identified. From 48 Mycobcterium isolates from pigs with lesions, 37 (77.0%) were identified by PRA as M. avium type 1, and 11 (23.0%) M. avium type 2. Among limph nodes with lesions wer ... / Doutor