Project description:Legionella pneumophila, an intracellular pathogen responsible for the pneumonia-like Legionnaires’ disease in humans, inhabits aquatic environments, including man-made water systems such as water fountains, foot spas, and tap water, and exists as part of biofilms or as a protozoan parasite. As a bacterivore, Tetrahymena thermophila provides a favorable environment for Legionella to establish a replicative niche (Legionella-containing vacuole; LCV) under environmental stress. Conversely, the L. pneumophila Ofk308 strain, isolated from an Ashiyu foot spa, has been found to be cytotoxic to the ciliate T. thermophila CU427. This study aimed to identify the cytotoxicity-related genes of Legionella and elucidate their mechanisms specific to the Tetrahymena host. A comparative analysis using RNA-sequencing was conducted with two Legionella strains, Philadelphia-1 and Ofk308, to select several candidate genes. Deletion mutants of Ofk308 were constructed by homologous recombination. Eight out of ten candidate gene deletion mutants were successfully generated. These mutants were analyzed for cytotoxicity against T. thermophila and intracellular bacterial growth at 2 h, 24 h, and 48 h postinfection. Among the deletion mutants, ∆vicinal oxygen chelate (VOC) and msrB/A exhibited reduced cytotoxicity. Furthermore, LCVs formed in T. thermophila infected with ∆VOC and msrB/A were smaller in size compared to those formed by the parental strain Ofk308, suggesting a role in both cytotoxicity and intracellular growth. Multiple factors contribute to the cytotoxicity exhibited by the Ofk308 strain in protozoan host cells, and gene expression analysis may reveal additional relevant factors.
Project description:Single-molecule read technologies allow for detection of epigenomic base modifications during routine sequencing by analysis of kinetic data during the reaction, including the duration between base incorporations at the elongation site (the "inter-pulse duration.") Methylome data associated with a closed de novo bacterial genome of Salmonella enterica subsp. enterica serovar Javiana str. CFSAN001992 was produced and submitted to the Gene Expression Omnibus. Single-sample sequencing and base modification detection of cultured isolate of a foodborne pathogen.
Project description:Strain Cad16T was previously shown to fix a major fraction of the bulk CO2 under both light and dark conditions and was suggested to be involved in Fe(II) driven aerobic metabolism in the lake Cadagno chemocline. However evidence on genomic and proteomic level was only fragmentary . In order to understand the biological functions expressed under phototrophic and chemotrophic growth conditions of str. Cad16T an in situ experiment conceived. It included cultures of str. Cad16T incubated in dialysis bags for three months while physiochemical conditions were monitored longitudinally. Upon sampling, physiological differences of str. Cad16T were compared utilizing quantitative proteomics in combination with CO2-uptake measurements.