Utilización de microorganismos para la producción de energías renovables

Traballo fin de grao (UDC.CIE). Bioloxía. Curso 2012/201

Desarrollo de cepas atenuadas de Rhodococcus equi mediante la obtención de cepas afectadas en los sistemas de oxidación reducción

La idea de esta Tesis surge por la confluencia de varios factores (i) la importancia del microorganismo en estudio, Rhodococcus equi, para la industria equina y para la salud humana; (ii) el incremento en la resistencia de los microorganismos a los diferentes antibióticos; (iii) la experiencia previa del grupo en el estudio de los sistemas de control Redox (oxidación/reducción) en algunos representantes del grupo de las actinobacterias. R. equi es una bacteria Gram positiva perteneciente al grupo de las actinobacterias presente en suelos de diferentes ambientes, entre ellos pastizales; la bacteria puede comportarse como un patógeno intracelular, causando bronconeumonía (y muerte) en potros, pero también ocasionalmente en pacientes inmuno-suprimidos

Mycoredoxins Are Required for Redox Homeostasis and Intracellular Survival in the Actinobacterial Pathogen Rhodococcus equi

[EN] Rhodococcus equi is a facultative intracellular pathogen that can survive within macrophages of a wide variety of hosts, including immunosuppressed humans. Current antibiotherapy is often ineffective, and novel therapeutic strategies are urgently needed to tackle infections caused by this pathogen. In this study, we identified three mycoredoxin-encoding genes (mrx) in the genome of R. equi, and we investigated their role in virulence. Importantly, the intracellular survival of a triple mrx-null mutant (Δmrx1Δmrx2Δmrx3) in murine macrophages was fully impaired. However, each mycoredoxin alone could restore the intracellular proliferation rate of R. equi Δmrx1Δmrx2Δmrx3 to wild type levels, suggesting that these proteins could have overlapping functions during host cell infection. Experiments with the reduction-oxidation sensitive green fluorescent protein 2 (roGFP2) biosensor confirmed that R. equi was exposed to redox stress during phagocytosis, and mycoredoxins were involved in preserving the redox homeostasis of the pathogen. Thus, we studied the importance of each mycoredoxin for the resistance of R. equi to different oxidative stressors. Interestingly, all mrx genes did have overlapping roles in the resistance to sodium hypochlorite. In contrast, only mrx1 was essential for the survival against high concentrations of nitric oxide, while mrx3 was not required for the resistance to hydrogen peroxide. Our results suggest that all mycoredoxins have important roles in redox homeostasis, contributing to the pathogenesis of R. equi and, therefore, these proteins may be considered interesting targets for the development of new anti-infectivesS

Understanding microRNAs in the Context of Infection to Find New Treatments against Human Bacterial Pathogens

[EN] The development of RNA-based anti-infectives has gained interest with the successful application of mRNA-based vaccines. Small RNAs are molecules of RNA of <200 nucleotides in length that may control the expression of specific genes. Small RNAs include small interference RNAs (siRNAs), Piwi-interacting RNAs (piRNAs), or microRNAs (miRNAs). Notably, the role of miRNAs on the post-transcriptional regulation of gene expression has been studied in detail in the context of cancer and many other genetic diseases. However, it is also becoming apparent that some human miRNAs possess important antimicrobial roles by silencing host genes essential for the progress of bacterial or viral infections. Therefore, their potential use as novel antimicrobial therapies has gained interest during the last decade. The challenges of the transport and delivery of miRNAs to target cells are important, but recent research with exosomes is overcoming the limitations in RNA-cellular uptake, avoiding their degradation. Therefore, in this review, we have summarised the latest developments in the exosomal delivery of miRNA-based therapies, which may soon be another complementary treatment to pathogen-targeted antibiotics that could help solve the problem caused by multidrug-resistant bacteriaSIWe thank the Junta de Castilla y León (Spain) for funding our research work on microRNAs, grant number LE044P20. A.M. is supported with a postdoctoral fellowship “Margarita Salas”. M.L. is the recipient of a “Beatriz Galindo” grant (Ref. BEAGAL18/00068 - BGP18/00033

Desarrollo de cepas atenuadas de "Rhodococcus equi" mediante obtención de cepas afectadas en los sistemas de oxidación reducción = Development of attenuated "Rhodococcus equi" strains affected in its oxidation reduction mechanisms

215 p.Se han estudiado los mecanismos de oxidación reducción de una bacteria patógena denominada Rhodococcus equi, la cual es el agente causal de neumonía en potros y en seres humanos, principalmente inmunosuprimidos. El desarrollo de cepas atenuadas de esta bacteria, mediante la deleción de ciertos genes claves para la colonización intracelular ha sido el tema centra de la tesis. Concretamente, el estudio se ha centrado en la importancia de los sistemas basados en micorredoxinas y tiorredoxinas extracelulares, los cuales han demostrado ser esenciales para la virulencia de la bacteria descubriéndose así nuevos factores de virulencia que pueden ayudar en el desarrollo de nuevos y mejores tratamientos