ABSTRACT
Ralstonia pseudosolanacearum GMI1000 (Rpso GMI1000) is a soil-borne vascular phytopathogen that infects host plants through the root system causing wilting disease in a wide range of agro-economic interest crops, producing economical losses. Several features contribute to the full bacterial virulence. In this work we study the participation of light, an important environmental factor, in the regulation of the physiological attributes and infectivity of Rpso GMI1000. In silico analysis of the Rpso genome revealed the presence of a Rsp0254 gene, which encodes a putative blue light LOV-type photoreceptor. We constructed a mutant strain of Rpso lacking the LOV protein and found that the loss of this protein and light, influenced characteristics involved in the pathogenicity process such as motility, adhesion and the biofilms development, which allows the successful host plant colonization, rendering bacterial wilt. This protein could be involved in the adaptive responses to environmental changes. We demonstrated that light sensing and the LOV protein, would be used as a location signal in the host plant, to regulate the expression of several virulence factors, in a time and tissue dependent way. Consequently, bacteria could use an external signal and Rpsolov gene to know their location within plant tissue during the colonization process.
Subject(s)
Bacterial Proteins/genetics , Host-Pathogen Interactions/physiology , Ralstonia/physiology , Solanum lycopersicum/microbiology , Bacterial Adhesion/physiology , Bacterial Proteins/metabolism , Biofilms/growth & development , Gene Expression Regulation, Bacterial , Light , Polysaccharides, Bacterial/genetics , Polysaccharides, Bacterial/metabolism , Ralstonia/pathogenicityABSTRACT
The first report of Ralstonia mannitolilytica bacteremia in Peru is presented. The patient was a pediatric cancer patient with a long-term central venous access device. For the diagnosis, the MicroScan Walk Away 96 automated system was used. 16S rDNA was amplified by conventional PCR, and the bacterial genus and species were identified by genetic sequencing. In addition, the bacterial resistance profile to major antimicrobials was determined. The article discusses the need to actively monitor Ralstonia mannitolilytica, especially in hospital areas of immunocompromised patients.
Se presenta el primer reporte de una bacteriemia por Ralstonia mannitolilytica en Perú. Se trata de un paciente pediátrico con cáncer que porta un dispositivo de acceso venoso central de larga duración. Para establecer el diagnóstico, se utilizó el sistema automático MicroScan Walk Away 96. Se amplificó el rADN 16S mediante PCR convencional y se identificó el género y la especie bacteriana mediante secuenciación genética. Además, se determinó el perfil de resistencia bacteriana a los principales antimicrobianos. El artículo discute la necesidad de monitorizar activamente la presencia de Ralstonia mannitolilytica, especialmente en áreas hospitalarias de pacientes inmunodeprimidos.
Subject(s)
Bacteremia , Ralstonia , Bacteremia/diagnosis , Bacteremia/drug therapy , Child , Hospitals , Humans , Peru , Ralstonia/genetics , Ralstonia/pathogenicityABSTRACT
The extensive genetic diversity of Ralstonia solanacearum, a serious soil-borne phytopathogen, has led to the concept that R. solanacearum encompasses a species complex [R. solanacearum species complex (RSSC)]. Insertion sequences (ISs) are suggested to play an important role in the genome evolution of this pathogen. Here, we identified and analysed transposable elements (TEs), ISs and transposons, in 106 RSSC genomes and 15 Ralstonia spp. We mapped 10â259 IS elements in the complete genome of 62 representative RSSC strains and closely related Ralstonia spp. A unique set of 20 IS families was widespread across the strains, IS5 and IS3 being the most abundant. Our results showed six novel transposon sequences belonging to the Tn3 family carrying passenger genes encoding antibiotic resistance and avirulence proteins. In addition, internal rearrangement events associated with ISs were demonstrated in Ralstonia pseudosolanacearum strains. We also mapped IS elements interrupting avirulence genes, which provided evidence that ISs plays an important role in virulence evolution of RSSC. Additionally, the activity of ISs was demonstrated by transcriptome analysis and DNA hybridization in R. solanacearum isolates. Altogether, we have provided collective data of TEs in RSSC genomes, opening a new path for understanding their evolutionary impact on the genome evolution and diversity of this important plant pathogen.