The acidic O-polysaccharide (O-antigen) of Escherichia coli O30 was isolated from the lipopolysaccharide and studied by sugar analysis and NMR spectroscopy. The following structure of the branched tetrasaccharide repeating unit was established, which is unique among known structures of bacterial polysaccharides: ?-D-GlcpNAc--1?2--?4)-?-D-GlcpA-(1?4)-?-D-GlcpA-(1?3)-?-D-GlcpNAc-(1? The O-antigen gene cluster of E. coli O30 was sequenced. The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in full agreement with the O-polysaccharide structure.
Salmonella is a major cause of food-borne disease in many countries. Serotype determination of Salmonella is important for disease assessment, infection control, and epidemiological surveillance. In this study, a microarray system that targets the O antigen-specific genes was developed for simultaneously detecting and identifying all 46 Salmonella O serogroups. Of these, 40 serogroups can be confidently identified, and the remaining 6, in three pairs (serogroups O67 and B, E1 and E4, and A and D1), need to be further distinguished from each other using PCR methods or conventional serotyping methods. The microarray was shown to be highly specific when evaluated against 293 Salmonella strains, 186 Shigella strains, representative Escherichia coli strains, and 10 strains of other bacterial species. The assay correctly identified 288 (98%) of the Salmonella strains. The detection sensitivity was determined to be 50 ng genomic DNA per sample. By testing simulated samples in a tomato background, 2 to 8 CFU per gram inoculated could be detected after enrichment. This newly developed microarray assay is the first molecular protocol that can be used for the comprehensive detection and identification of all 46 Salmonella O serogroups. Compared to the traditional serogrouping method, the microarray provides a reliable, high-throughput, and sensitive approach that can be used for rapid identification of multiple Salmonella O serogroups simultaneously.
Related JoVE Video
Journal of Visualized Experiments
What is Visualize?
JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.
How does it work?
We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.
Video X seems to be unrelated to Abstract Y...
In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.