Project description:Vibrio cholerae uses multiple strategies to resist predation by heterotrophic protozoa. For example, V. cholerae releases toxic compounds such as ammonium and pyomelanin, that can kill protists such as Tetrahymena pyriformis. V. cholerae also survives intracellularly and escapes as viable cells inside protozoan expelled food vacuoles (EFVs). We previously reported that V. cholerae encased in EFVs are hyperinfectious, establishing an important link between anti-protozoal strategies and bacterial virulence. Although the intracellular resistance and escape of V. cholerae in EFVs has been reported, the molecular mechanisms behind this remain poorly understood. Here, we used single cell transcriptomics of V. cholerae exposed to T. pyriformis and captured a total of 5,344 bacterial cells with heterogeneous gene expression. Cells with the same pattern of gene expression were grouped, resulting in eleven clusters of cells with a unique gene expression profile. Genes encoding outer membrane proteins, F1F0-Na+/H+ ATPase, metabolites and toxins showed differential expression among the clusters. Furthermore, the motility-associated killing factor (Mak) toxins (makA, makB and makC) were differentially expressed. Individual V. cholerae ΔmakA, ΔmakB, and ΔmakE strains were not capable of killing T. pyriformis and ΔmakA and ΔmakE showed reduced survival inside EFVs compared to the wild type. Our findings reveal new insights into the grazing resistance mechanisms of V. cholerae, identify factors associated with the survival of V. cholerae within EFVs and more broadly, highlight the connection between antiprotozoal and virulence factors displayed by pathogenic bacteria.
Project description:The primary objective of this prospective observational study is to characterize the gut and oral microbiome as well as the whole blood transcriptome in gastrointestinal cancer patients and correlate these findings with cancer type, treatment efficacy and toxicity. Participants will be recruited from existing clinical sites only, no additional clinical sites are needed.