Project description:Humans and microorganisms, both symbiotic and pathogenic, have evolved means to communicate through the dissemination of biological signals. In addition to small molecules and proteins, mobile small RNAs (sRNAs) have recently emerged as signal molecules that mediate inter-species crosstalk by functional RNA interference (RNAi). However, the trafficking of sRNAs between humans and microorganisms, as well as the resulting biological consequences, remains unexplored. Here, we report that human cells secrete exosomes to deliver sRNAs into bacteria and induce bacterial gene silencing. The unprecedented RNAi in bacteria is accomplished primarily through translational repression without mRNA degradation, for which the participation of human AGO2 proteins co-transferred with sRNAs is essential. Exosome-mediated bacterial RNAi was further applied to fight superbug infection by targeting drug-resistance genes in a mouse model. Our discovery of this unique exosome-mediated sRNA delivery and gene silencing in bacteria paves the way to understanding and manipulating the cross-kingdom communication between human hosts and intestinal microbiota, as well as between humans and pathogenic bacteria.
Project description:A prototype oligonucleotide microarray was designed to detect and identify viable bacterial species with the potential to grow of common beer spoilage microorganisms from the genera Lactobacillus, Megasphaera, Pediococcus and Pectinatus. Probes targeted the intergenic spacer regions (ISR) between 16S and 23S rRNA, which were amplified in a combination of reverse transcriptase (RT) and polymerase chain reaction (PCR) prior to hybridization. This method allows the detection and discrimination of single bacterial species in a complex sample. Furthermore, microarrays using oligonucleotide probes targeting the ISR allow the distinction between viable bacteria with the potential to grow and non-growing bacteria. The results demonstrate the feasibility of oligonucleotide microarrays as a contamination control in food industry for the detection and identification of spoilage microorganisms within mixed population. Keywords: microarray, oligonucleotide, species-specific, detection, beer spoilage bacteria