La marchitez bacteriana del tomate causada por Ralstonia solanacearumes un problema recurrente en el estado de Morelos y otras partes de México y el mundo. Los métodos actuales para el control de este fitopatógeno bacteriano se basan en el uso de antibióticos que promueven la selección de bacterias resistentes y en agroquímicos que son tóxicos para los humanos, las plantas y el medio ambiente en general. Estos métodos de control degradan la calidad de los suelos al eliminar gran parte de la microbiota normal debido a su amplio espectro de acción. Esta situación pone de manifiesto la necesidad de desarrollar métodos de control alternativos que estén alineados con el desarrollo sostenible de la agricultura. Los bacteriófagos líticos ofrecen una alternativa de control debido a su alta especificidad, baja toxicidad y capacidad de auto-amplificación. En este trabajo se reporta el aislamiento,R. solanacearum . Este bacteriófago pertenece a la familia Mioviridae y genera placas de lisis de aproximadamente 0.5 cm de diámetro después de 24 h de incubación, que continúan aumentando su tamaño con el tiempo. Este bacteriófago tiene la capacidad de aclarar los cultivos líquidos de R. solanacearum a muy pocas multiplicidades de infección y es estable en la solución nutritiva detectada para el cultivo de tomate hidropónico, en un rango de pH de 4 a 11; sin embargo, es inestable en agua ultrapura. Los resultados indicados que el bacteriófago ФRSP presenta características que lo señalan como un buen candidato para ser utilizado como agente de control biológico contra la marcha bacteriana causada por R. solanacearum.
The use of colistin in food-producing animals favors the emergence and spread of colistin-resistant strains. Here, we investigated the occurrence and molecular mechanisms of colistin resistance among E. coli isolates from a Mexican piglet farm. A collection of 175 cephalosporin-resistant colonies from swine fecal samples were recovered. The colistin resistance phenotype was identified by rapid polymyxin test and the mcr-type genes were screened by PCR. We assessed the colistin-resistant strains by antimicrobial susceptibility test, pulse-field gel electrophoresis, plasmid profile, and mating experiments. Whole-Genome Sequencing data was used to explore the resistome, virulome, and mobilome of colistin-resistant strains. A total of four colistin-resistant E. coli were identified from the cefotaxime-resistant colonies. All harbored the plasmid-borne mcr-1 gene, which was located on conjugative 170-kb IncHI-2 plasmid co-carrying ESBLs genes. Thus, high antimicrobial resistance rates were observed for several antibiotic families. In the RC2-007 strain, the mcr-1 gene was located as part of a prophage carried on non-conjugative 100-kb-plasmid, which upon being transformed into K. variicola strain increased the polymyxin resistance 2-fold. The genomic analysis showed a broad resistome and virulome. Our findings suggest that colistin resistance followed independent acquisition pathways as clonal and non-genetically related mcr-1-harboring strains were identified. These E. coli isolates represent a reservoir of antibiotic resistance and virulence genes in animals for human consumption which could be potentially propagated into other interfaces.
BackgroundMalaria parasites are transmitted by Anopheles mosquitoes. Although several studies have identified mosquito midgut surface proteins that are putatively important for Plasmodium ookinete invasion, only a few have characterized these protein targets and demonstrated transmission-blocking activity. Molecular information about these proteins is essential for the development of transmission-blocking vaccines (TBV). The aim of the present study was to test three monoclonal antibodies (mAbs), A-140, A-78 and A-10, for their ability to recognize antigens and block oocyst infection of the midgut of Anopheles albimanus, a major malaria vector in Latin America.MethodWestern-blot of mAbs on antigens from midgut brush border membrane vesicles was used to select antibodies. Three mAbs were tested by membrane feeding assays to evaluate their potential transmission-blocking activity against Plasmodium berghei. The cognate antigens recognized by mAbs with oocyst-reducing activity were determined by immunoprecipitation followed by liquid chromatography tandem mass spectrometry.ResultsOnly one mAb, A-140, significantly reduced oocyst infection intensity. Hence, its probable protein target in the Anopheles albimanus midgut was identified and characterized. It recognized three high-molecular mass proteins from a midgut brush border microvilli vesicle preparation. Chemical deglycosylation assays confirmed the peptide nature of the epitope recognized by mAb A-140. Immunoprecipitation followed by proteomic identification with tandem mass spectrometry revealed five proteins, presumably extracted together as a complex. Of these, AALB007909 had the highest mascot score and corresponds to a protein with a myosin head motor domain, indicating that the target of mAb A-140 is probably myosin located on the microvilli of the mosquito midgut.ConclusionThese results provide support for the participation of myosin in mosquito midgut invasion by Plasmodium ookinetes. The potential inclusion of this protein in the design of new multivalent vaccine strategies for blocking Plasmodium transmission is discussed.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1548-8) contains supplementary material, which is available to authorized users.
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